Can a pellet gun go “overbore”?

by B.B. Pelletier

There’s a new instructional video on Airgun Academy. It’s all about dot sights. Click to see it.

Announcement: Mary Kulesa Geraci is this week’s winner of Pyramyd Air’s Big Shot of the Week on their facebook page. She’ll receive a $50 Pyramyd Air gift card.

Mary Kulesa Geraci wins this week’s Big Shot of the Week.

Last week at a gun show, I learned something that eluded me all my life. I learned what overbore means and why it matters so much.

I was introduced to the .250 Savage cartridge, which is also called the .250/3000. It is one of the smaller .25-caliber cartridges today, but when it was first introduced back in the early part of the 20th century it was a screamer — the fastest .25-caliber cartridge around. It wasn’t the biggest, mind you. That honor probably went to the .25 Krag, which was a .30/40 Krag necked down to .25 caliber. It held more powder, but its bullets went no faster.

In fact, if you look at the reliable reloading books today — not online, where you can find anything — the .250 Savage is still faster than the .257 Roberts with an identical 100-grain bullet. I couldn’t believe that, but according to my Lyman manual, 48th edition, the top safe loads for the .250 Savage go faster and use less powder than the .257 Roberts.

I don’t want to start an argument about this — it could probably go either way, depending on the manual you read. The point is that the .250 Savage is a mild-mannered and small centerfire that delivers the same punch as a well-respected middleweight round.

It does so, according to Harvey Donaldson because the cartridge case volume is optimum for the caliber. A deer hit by a 100-grain spitzer soft-point traveling 2,700 f.p.s. will not pause to inquire what cartridge case launched it. Donaldson designed his .219 Wasp to do the same thing. It delivers the ballistics of a .22/250 with far less powder and pressure. That leads me to my real discussion point for today.

Is there such a thing as an optimum caliber/velocity ratio for an airgun, along the same lines that I have just described for a centerfire rifle? I think there may be, though I’m pretty sure I don’t know what it is.

I suspect there’s a velocity range that’s optimum for each caliber; and within that range, most guns and most pellets will do their best. This range may even be defined by the type of powerplant that generates it. If I knew this for sure, my job of teaching new airgunners would be so much easier.

Well, I may not know the optimum, but here’s what I do know.

1. If you shoot a .177 pellet at 650-750 f.p.s. in a spring rifle with a good barrel, it’ll be as accurate as that rifle will ever get. But if you try to increase that by as little as 100 f.p.s., you run the risk of creating a nasty monster. The HW 35 comes to mind when I say that. Left at its factory velocity of 725-750, the .177-caliber HW 35 is a gentle giant. But try to push it up to 850 f.p.s., and the rifle becomes hard to cock, buzzy and a real pain to shoot.

The reverse is also true. Take a .177-caliber Beeman R1 that delivers 1,000 f.p.s. right out of the box and detune it to 850 f.p.s., and it settles down. That isn’t quite the low range I stated, but it’s going in the right direction.

2. A spring rifle that delivers over 1,000 f.p.s. will almost certainly be extremely hold-sensitive. I dread testing the mega-magnums when it comes time for the accuracy test, because I’ve seen it go bad so many times.

3. A .22-caliber spring rifle gets twitchy at around 900 f.p.s. and above. As long as I keep the velocity below that speed, I seem to get the best performance from the gun. You may have wondered why I have spent so much extra time on some airguns but not others. This is part of the reason why.

4. Precharged airguns are entirely different than springers. They handle velocity better, but even they have upper limits. I have seen some PCPs do well at slightly above 1,000 f.p.s., but that’s about the point at which they start to fall apart.

5. Big bore airguns haven’t yet reached their full potential in any caliber I’ve tested to this time. I think a big bore PCP could tolerate 1,200 f.p.s., if it could get the bullet up to that speed. And that statement only goes for real bullets — not for hollow-based “pellet” designs.

But back to my question. Do you think there might be an optimum velocity/caliber relationship, and would it hold across models and pellets types? And a corollary: If there’s such a relationship, is there also a pretty good chance that when a pellet is driven too fast that it becomes increasingly harder to shoot accurately?

Is there a way to test this? I have the Whiscombe that I can adjust to change velocities for the same pellets. But how would we test for this relationship? What should be taken into account? And would the test be with a single pellet, or would it be with several pellets?

One final thought. Above, I said that pellets in the 650 to 750 f.p.s. range are usually the most accurate, but what about when those pellets go even slower? What happens then? I know something happens, because I have air rifles that shoot slower than 650 f.p.s. that are very accurate. Yesterday’s test of the HW 55CM is a good example. Should we also put some kind of distance requirement into this experiment?

What are you smoking, B.B.?
What brought this on is that I’ve been eyeing my Beeman R8 recently, but I don’t have a reason to use it in a test. But it’s such a nice, accurate air rifle that I just want to shoot it a lot. I was hoping to find some justification for shooting the R8 more, even if it’s only to cleanse my pallet after the test of some 1,300 f.p.s. hyper-blaster.

But I’m serious. If there’s some sort of velocity/caliber relationship that’s optimum, then we’ll have discovered a powerful tool for the new airgunner who is looking for that first gun. “Sure, you can get the .177 Bow of Hercules if you want, but just remember that the immutable laws of airgunning dictate that the most accurate air rifle will always be….”

147 thoughts on “Can a pellet gun go “overbore”?

  1. There is a law of diminishing returns that applies to nearly everything. In the classic car world a 1969 Camaro Z28 had that near perfect balance and harmony you speak of. In the Springer world there are a few, and your R8 is probably is one of them. The plain older HW50’s even more so.

    I think that is the reason the R7 is so popular. Light weight, low cocking effort and nice results. I spent a good bit of time searching for such a Nirvana and for me it is the ________________.


  2. I have a question about something. If the ak 74 has a longer sight adjustment range than m16 ( 1000 meters comparing to 800 m ) and also a longer effective range (625 comp. to 550) , why everyone says that m16 is the more accurate weapon. Is this because of it’s small recoil, or because of it’s bullet?

    Thanks


    • Don’t confuse the “effective range” derived from the bullet’s power with the rifle’s inherent accuracy. The 1000 meter sight adjustment on the AK is either highly optimistical or not made to engage human individuals – soldiers don’t shoot at humans only.


      • Thanks for reply. Do you want to say that the bullet has low chances to reach 1000 meters ( considering flat battlefield, no obstacles) ? If yes, why do they even use this information ?


        • Krikman,

          Are you referring to the maximum effective range of the bullet, or the maximum functional range of the sites? BIG difference. I’m sure Mel is referring to the bullets.

          ka


        • Krikman,

          A bullet from a modern centerfire rifle travels a maximum of 2,500 to 5,000 meters, depending on the caliber and the ballistic coefficient of the bullet. That would be if the axis of the bore were elevated 30-35 degrees to the horizon, which gives the maximum flight.

          Large lead bullets from the old-time big bore blackpowder rifles of the 1880s went just as far, though they left the muzzle at a third of the velocity of a modern bullet. The U.S. Army verified this in the 1990s with millimeter wave radar that tracked the bullets in flight. Army ballisticians were trying to disprove Billy Dixon’s famous shot where he shot an indian off his horse at 1,550 yards during the Battle of Adobe Walls in Texas, and instead they proved that it was possible. But don’t expect that a soldier using a modern military rifle could come anywhere close to that kind of accuracy, because they can’t.

          B.B.




            • Victor,

              Well, that was the position all the Army physicists took. They said it was impossible. Yet their own radar proved that it was happening that way.

              This test is now very famous and has been quoted and reproduced many times over the past 20 years. It is the basis for me saying that to obtain the maximum range from a gun the barrel must be inclined 30-35 degrees to the horizon, instead of the 45 degrees that everyone believes.

              Here is a greatly shortened synopsis of that test:

              http://powderburns.tripod.com/sharps.html

              B.B.


          • It’s not impossible, not even remotely difficult actually, to throw a projectile over such a distance. It’s simply a matter of momentum and drag. A heavy enough bullet of old that doesn’t generate a whole lot of drag will fly as far as anything modern. Don’t expect to hit anything with it, but it’ll get there 😉

            Low drag is much easier with subsonic bullets, they’ve got half to a quarter of the drag coefficient of a supersonic bullet (depending on how fast it’s going), AND they travel at a much lower velocity (drag being directly related to V^2)… yeh, for the same momentum ye’ olde’ subsonic will likely go further, just because it’s bleeding off its momentum much slower.

            By the way, the .50BMG (or 12.7×99 if you’re a NATO official…) has a stated lethal energy range of over 10km! It’s only good to about 2 of course (or half if you employ any of Ronnie Barrett’s *straight blowback* semi autos…), but this underlines the absolute necessity for a more than adequate backstop when foolin’ around with something like that 😀


        • At the right angle, even the lowly .22LR can reach or exceed 1mile…

          Some old military fogies were probably visualizing a repeat of Agincourt at rifle distances (the English longbows on the flanks were not aiming at any particular foe, but doing massed fire lobbing arrows into the middle of a field filled with French troops — didn’t even need the carefully prepared accurate arrows).

          Now imagine some stuffy old general visualizing a battle plan consisting of riflemen hidden in the trees on the flanks, lobbing big heavy bullets into a field of cavalry that was still over half a kilometer away. Accuracy? no — but having a sight calibrated for the distance means being able to “aim” near the center of the formation and having a chance of hitting something.

          Of course, once you convert that cavalry to armored tanks, the equation shifts. (You try to lure individual tanks /into/ the forest, snipe off any infantry escort, and have your way with the dinosaur, uh – tank*)

          * old (1970 or so) army training booklet/comic “How to Kill a Tank” (I believe) compared tank killing to (anachronistically incorrect) killing dinosaurs by “cavemen”. The main concept was that a solitary tank in tight spaces without an infantry escort was easy pickings… (remember, at this time period the concept battle field was central Europe forests, NATO vs Soviets — not a repeat of the north African campaign shifted to the middle east) Molotov cocktails at the engine cooling vents, etc.


    • Might be more along the lines of how the effective range is defined. Just how do they figure that? You could put a really tall rear sight on a rifle and get the bullets in the right general area at some pretty long ranges, but can you have much hope of hitting a barn on purpose that far?

      twotalon


    • The M-16’s reputed superior accuracy could be due to its ergonomics, tolerances, something about the .223 caliber, the variety of loads that have been developed for the rifle. But that would be on a shooting range. Loaded down with a lot of accessories in the field and not cleaned scrupulously I doubt that there is any difference between the two rifles. Even on the shooting range, gun writers do not get much below 2 MOA out of AR-15s that often cost a fortune.

      Matt61



      • That might have something to do with said gun writers’ abilities, though I’m just as inclined to blame the gun. So many “high end” manufacturers appear to be utterly inept at building a light and accurate AR, it’s just ridiculous.

        Cost is often a poor indicator of performance – a 10k super high end “tactical” AR might still fail to group better than a minute, while a 1.5k custom home build (the much berated “hobby” ARs) would often shoot half a minute with good ammo. Quarter minute groups out of ARs aren’t entirely unheard of, but are extremely rare… mind you, they’re rare at best with match grade target weapons, so getting something like that out of an AR might as well be a miracle! That kind of performance however lies firmly in meticulous hand load territory, both for ARs and bolt actions.


    • Lots of things go into both accuracy and effective range. As far as the graduations are concerned, it’s not impossible to send a 5.45 (what the AK74 is chambered in) a km away and even hit something with one, but it’s generally uncommon and you have to have the right weapon to do it. Not every AK can throw that far and hit a target you can see, not even every Izhmash one. We’re talking forged and milled action, VERY high end barrel, good ammo and an amazing shooter before you even try to pull something like that off, but I’ve seen it done.

      That said, neither the 5.56 nor 5.45 carry enough energy at that distance to be able to do much even if you do hit what you’re aiming at.

      Recoil-wise, it’s not too bad. The smaller, lighter bullet can carry more energy with less momentum (mv vs 1/2mv^2), so it would recoil less than an AK47 (and any other 7.62×39 variant) to begin with, but on top of that it also has a big ass muzzle brake to further help with it.

      The biggest difference between the AR-15 platform (standard variety) and Kalashnikovs is the type of gas system employed, hand guard attachment and their effect on barrel harmonics. The AR-15 was designed to use a direct gas impingement system. What that means is that there’s a small hole in the barrel allowing gas escape, which is connected to a hollow tube going back into the action and forwarding the gasses into the bolt. On the bolt, the gas key (which is also hollow) directs the gasses into a small vented cylinder (the two holes on the side of the bolt are the vents) with the bolt acting as the piston. This means that as the bolt unlocks no extra rearward load is placed on the locking lugs. After the bolt has unlocked, the bolt group is free to fly back. By that time, the carrier already has enough momentum to cycle, but there’s some pressure left in the gas tube, which gives it some more until the gas key disengages the gas tube.

      The main disadvantage of this system is that it throws hot gas and shyte right into the bolt, so is prone to causing malfunctions after some solid firing – it gets hot, it gets dirty and if it’s not built for that – it jams.

      Its advantages however are that it’s generally more tolerant to pressure changes (i.e. adding a sound suppressor) than a lot of piston implementations, there’s usually a lot less reciprocating mass and crucially – the only connection between all the moving parts and the barrel is a thin flexible tube, which doesn’t interfere with operation much.

      With it being a low profile system, the AR-15 also lends itself very well to free floating the barrel, much like a bolt action target rifle, which allows for much more consistent barrel harmonics.

      The best AR-15 implementations (1 – 2k “hobby” self builds, very streamlined no bullshit weapons) are often capable of 0.5MOA with the right ammo (we’re talking match grade) and the right shooter. A cold hammer forged barrel is a must with these weapons.

      With a well fitted barrel and a 7075-T6 action, any optic mounted on the weapon is effectively mounted to the barrel. It’s a stiff action, with ideally no motion of the barrel once fitted, which allows for great consistency of aiming and therefore consistency of shot placement. That coupled with the DI system’s minimal disruption to barrel harmonics results in a potentially very accurate platform.

      All that said, it’s EXTREMELY easy to get it wrong and end up with something unreliable or inaccurate (or both!) and usually something unnecessarily heavy.

      The AK platform on the other hand uses a long stroke piston system in a self adjusting configuration. In order to handle hotter loads, the bolt group is built like a tank. That allows it to withstand the shock of high powered ammunition without developing fatigue cracks (though if you make it out of poor materials it WILL fail).

      In the AK platform the gas port (that little hole in the barrel) is bigger to allow more gas through and to provide tolerance for dirty ammo (you don’t want shyte blocking your gas port – it’ll not cycle if you can’t get enough gas). The same approach has been taken with the cylinder, which isn’t cylindrical but corrugated. Other than the shape of the piston, very little effort is expended in ensuring a good gas seal. The corrugated cylinder literally allows gas to escape around the sides of the piston, with only its inner diameter providing anything remotely resembling a seal. It also has vent holes drilled along its length which act to significantly reduce gas pressure while the weapon is cycling. They also throw shite in your face if you’re firing dirty blanks!

      The result of these design decisions is a system which is *almost* impossible to foul up into failure (it has been done before, but it’s VERY difficult, something else usually fails before that). It will chew through low powered dirty ammo as if it were a match load!

      The one major downside is that the gas cylinder is effectively strapped to the barrel and as a result there’s a much stronger interaction, messing up harmonics and ultimately reducing accuracy. This has been one of the biggest gripes of AR guys with any piston platform (short or long stroke).

      Additionally, since it’s a long stroke system and the piston is part of the bolt group, you get a LOT more reciprocating mass, resulting in significantly more perceived recoil, observed mainly as muzzle rise due to the bore axis – stock alignment.

      The design of the piston system as well as the hand guard attachment system make it impossible to free float the barrel, so the inherent accuracy of this weapon is somewhat worse. The REALLY well made AK-47s can do 0.6-0.7MOA with the right ammo, the AK-74s group much better due to the dynamic responce of the bullet. It’s the same reason why 6.5 Creedmoor is so good.

      The problem is that most AKs aren’t made that well. The stated figures apply to Arsenal factory 10 units (made in Kazanlak, Bulgaria, standard issue for the army). At factory 10 they spend 5 hours forging the action before milling it and build barrels to Steyr spec under license. The result is a weapon that is extremely accurate for the type, maintains reliability and will never wear out. The downside is that if anything like that was made in the US it would be ridiculously expensive. Labour is MUCH cheaper in Bulgaria 😉

      Most AKs you’d encounter use stamped sheet metal actions and if you’re lucky – cold hammer forged barrels. The barrel technology is no detriment to accuracy, but means that they last comparatively shorter. The real problem is the stamped sheet metal action. There’s just too much flex in it compared to its forged and milled counterpart (which as we established is just too much effort for anyone else to bother with). Since any aiming device developed after the 19th century has to mount on a somewhat more convoluted rail system which is part of the already flimsy and flex-ready action (and let’s face it, aftermarket AK rails are often hit or miss) accuracy is greatly reduced. If you want to hit something you have to essentially not hold the weapon. Resting on sand bags would probably be the best solution to the problem of user induced flex, but it won’t help any recoil induced shifts in zero which stamped sheet metal actions are also prone to. The result is a weapon that shoots 1.5-2MOA at best.

      It all becomes much clearer once you account for the design intent behind these rifles.

      Back in the ’50s, Stoner and his team at Armalite (then a division of Fairchild) developed a light and accurate select fire .308Win sporting rifle for the civilian market (back when gun regulations were somewhat more factually and less ideologically driven). Christened the AR-10 (as in Armalite Rifle model 10), it didn’t sell remotely as well as Armalite had hoped it would. They then tried to flog it to the military, who’d by then had enough of the .308Win, so Armalite were forced to redevelop it for the wimpy little 5.56. By the time they were done, Armalite was becoming a money pit for Fairchild, so they decided to pull the plug on the operation rather than finance the military trials for the bastard child of a commercial rifle and military doctrine. The designs and patents relating to the AR-10 and AR-15 platforms were subsequently sold to Colt. The AR-15, now made by Colt, entered military service under the designation M16 and the rest is history.

      Mikhail Kalashnikov on the other hand was a military man. He’d served as a tank commander during WW2 and had had the chance to see the German Sturmgewehr 44 rifle, which likely served as inspiration (I submit the 7.92 bullet diameter as evidence). After the war he pursued his interest in firearms design which ultimately lead to his work on an intermediate cartridge select fire rifle, like the Stg44. His main gripe with that weapon was its reliability (or rather lack thereof) and its tendency to pull itself apart after heavy use. He wanted to make something simple enough to be able train the masses in its use and reliable enough to be mass produced on the cheap without risk of failure on the battlefield. As a result, his efforts were almost entirely focused on designing a reliable and tolerant platform, able to take anything a squaddie can throw at it and keep shooting. Initially the rifles were all milled, but in order to save cost and reduce weight, later design effort was focused on developing the necessary sheet metal technology and making the necessary design alterations. The reason stamped action AK variants are most popular today are the same – cost and weight.

      These two different design philosophies are the reasons behind the above discussed design compromises and go some way towards influencing the perception of the platforms.

      Hope this is of use to you


  3. I have a friend who took a sweet-driving Mazda Miata and thought he’d make it better with a V8 conversion kit, but he only created a monster! Just sayin’.

    To achieve the best possible ride and handling combination, a vehicle’s suspension damping must be ideally matched to the weight of the vehicle. With spring guns, I think harmony exists when the pellet weight is matched perfectly to the power of the spring, allowing the optimum cushion of air pressure to form in front of the piston. We know that when a pellet is too light, it may cause the piston to slam into the front of the compression chamber, because the pellet gets moving too quickly. This situation does not allow for that optimum cushion of air pressure to build, and doesn’t feel right during shooting.

    I believe a pellet that is too heavy does not get moving quickly enough, causing chamber pressure in front of the piston to be excessive, and the piston to end its travel early as it slams into the rock-hard, immovable airspace – no cushion here, get moving Mr. Pellet! I experience this when attempting to use 21-grain H&N Barracudas in my RWS 350 – they’re too heavy, I can feel it when I shoot. 14 to 18g is perfect.

    In my experience, both above conditions cause the firing cycle to be affected negatively, and accuracy may well suffer. But, when pellet weight is optimum, I think the gun will have the smoothest firing cycle and the most potentiel for accuracy. I say the power level of the gun must be matched to an ideal pellet weight to provide initial pellet movement at the correct rate which will create that ideal chamber pressure/cushion as the piston reaches the limit of its frontward travel. As far as spring guns go, I wonder if I see a relationship. It seems that pellets in the weight range where the greatest muzzle energy is produced will also provide the best shooting experience, but energy is slightly less at the upper and lower extremes of pellet weight, where I feel the firing cycle is hindered. Cheers!

    Ken


  4. B.B.,
    You have a wonderful test bed PCP, the Talon. You can change calibers and power levels with relative ease. And as you stated, your Whiscombe may be suitable as a springer test bed. Sounds like a good excuse to go out and play to me! What a job!


  5. B.B.

    I think you are dealing with two different animals here…internal and external ballistics. Each one has it’s own world to live in, but there is a point that they overlap and influence each other.
    I am pretty sure that any type of pellet has a particular best velocity and rotation rate for in flight stability over a range of distance. That’s provided that the pellet is perfect in dimension and balance (not going to happen).
    To get the pellet into flight, a lot of things happen first. The basic problem is to get the pellet launched in the right direction in the first place, in line with the bore, and without damage that affects symmetry and balance.
    What can cause the pellet to be damaged in the gun? Well…..
    Damage when loading, damage from power plant pressure (deformed skirt), and lead extrusion along the trailing edges of the head and skirt.

    Even if you could launch the perfect pellet (both to start with and still maintaining perfect symmetry after bore deformation) at the best velocity for best flight, you still have to get it pointed in the right direction. Recoil and vibration bite you at this point. They keep trying to point the muzzle in different directions.
    How you gonna keep the muzzle pointed the same way every time?
    You need a consistent pressure curve to get the pellet out of the barrel at the same point of barrel movement every time. BUT….Then you get bit by the extremely wild vibration patterns caused by the violent mega magnum power plants. You can’t get a pellet out of the barrel before the vibration gets to the muzzle . Not going to happen. Not even with the fastest powder burners.

    So what you gonna do to minimize vibration? Even at ANY power level when dealing with springers?
    Well, there is more to it than pellet weight alone. How the pellet fits and how thick the skirt is will affect how the pressure curve is developed. Bore friction will also affect the pressure curve. The whole thing becomes a juggling act to get the power plant running as smoothly and consistently as possible.

    Now somebody who actually knows something can have it. I need more coffee.

    twotalon


    • TwoTalon’s statement: I am pretty sure that any type of pellet has a particular best velocity and rotation rate for in flight stability over a range of distance…. Hold’s true to my experience.

      I mainly shoot .22caliber pcps.

      Now this is just my experience with my own guns, but I have found:
      13.43gr JSB Match do well 600fps-850fps.
      14.3gr JSB Exacts do well 550fps – 900fps.
      18.1gr JSB Exact Jumbo Heavies do well 650fps-900+fps
      21gr H&N-Baracuda/Beeman-Kodiak do well 750fps-900+fps
      25.4gr JSB Monsters do well 750fps-900+fps

      Anytime I attempt to shoot the above pellets out of those fps ranges my accuracy suffers, so I just don’t do it. I believe rotation rate is very important.


      • Pelletman,

        Holy cow! You have part of the answer? And it is velocity-based, but not as caliber-specific as I suggested?

        This is one place to begun, but we need more data.

        B.B.


        • BB,

          To give you another example…

          I got lucky and got a hot Benjamin 392 Steriod. So far I’ve only been able to test it with one pellet, the 13.43gr JSB Match. From pumps 4-12, 600fps-840fps, I get consistent accuracy. At the same distance 4 pumps shoots directly below 12 pumps, and if I shoot groups with the same number of pumps, I get ragged one hole groups.

          Now if I venture to 13-14 pumps, 850+fps, the 13.43grJSB Matchs start flinging at 2 oclock of my aim point, and not into a ragged one hole group, but sporadic. I start shooting at 4-12pumps again, and all is good.

          TwoTalon brought up a good point, about pellets being altered/damaged (skirt being blown out) due to increased air pressure. Maybe thats what is happenning at 13+ pumps. Even if that is the case, the overall affect is velocity/rotation-rate for a what a given pellet can optimally work within. If the attempt is to get a pellet to shoot above its metalurgical stress point, then you are asking for sporadic results.

          If your definition for accuracy is a one-hole ragged group over a distance (which is mine ; shooting the eye out of a squirrel at 25+ yards), find your pellet’s optimum fps range, and just stick to it…


          • p.s. – Learned the same thing with my Condor (keep in mind I don’t have it adjusted all the way
            up)….

            When I fill the air tank to 3000psi, 25.4gr JSB monsters shoot unacceptable groups because
            the fps is not in the desired range for the pellet.

            Once the air tank pressure starts dropping, ergo the velocity starts climbing above 750fps,
            the Condor starts tack-driving, and the accuracy doesn’t falter unless I’m shooting below
            750fps again….


          • I don’t think anything but a springer/ram is going to damage skirts , because they have the highest pressure pulse.
            I tried catching pellets in a trash can full of water. Several kinds of pellets were used. They were shot with an R7 and an R9 (both .177). The shot pellets were compared to pellets of like kind to each other, and to pellets that were simply pushed through the barrel with a cleaning rod. All of the pellets had a feel of loading the same way, except the cplhp.

            The R7 fired pellets looked just like the ones that were only pushed through the bore. The R9 fired pellets showed a distinct belling out in the skirt. The cplhp, which fit unusually tight, showed the WORST distortion. How about that for the HARDEST pellet?

            The skirts on NONE of the pellets were expanded out to seal the bottom of the grooves.

            No attempt was made to get a detonation with some oil (sorry, Gamo). I already know that such things REALLY blow out a pellet, and into the bottom of the grooves too!

            So how do you deform a pellet skirt with too much pressure and do it symmetricaly? And how does this change aerodynamics?

            twotalon


            • Thats right….a pcp and pnematic is more of a push, that quickly picks up speed… So chances are,…no pellet deformation.

              So past 13+pumps on my Steroid is probably a pellet rotation, wobble, centrifugal force issue…


    • Assuming you had flawless interior ballistics, this would still be a massive dynamic stability problem. It’s almost entirely velocity driven and is practically unavoidable.

      Most air weapons are designed to fire at subsonic velocities, as are most pellets. This means that they’re generally very stable in flight, requiring comparatively little spin to maintain static stability and are geometrically designed to maintain a fairly good dynamic stability balance. Once you get past a certain velocity, these pellets enter the transonic flight speed range. This is generally a very nasty place to be. The pellet isn’t supersonic… well not entirely, it’s going fast enough to cause shockwaves to form at certain places around the geometry, but they’re nothing like the standard forward – aft shock configuration you’d see on a normal bullet. These little buggers are small, but strong, and fluctuate like crazy. They show up, nudge your pellet some way and then disappear before anyone notices. They’re extremely unpredictable and wreak havoc on dynamic stability and often – static stability.

      Stability-wise, the main problem you have is that when a pellet enters the transonic range (and you can often hear that happening if you have a well suppressed PCP) at very least there will be a massive increase in drag. Drag coefficient goes up four times as soon as the shocks appear. The shocks more importantly also cause a dramatic rise in pitching moment slope (the rate at which pitching moment increases with incidence angle), meaning that your typically stable pellet now needs to spin a whole lot faster to stop it tumbling. Now, this condition is only present for a split second – while the pellet is going fast enough to produce these shocks – due to all this extra drag, which means that even if some high amplitude stability mode was achievable (very sharp spiraling, obvious corkscrew motion) under the conditions, they’re only there long enough to nudge the pellet out of its perfect trajectory. That sharp transition further upsets dynamic stability due to the lag between an upsetting and restoring aerodynamic action (more common in air rifle pellets than in firearm bullets) as well as the gyroscopic interaction. Even if it’s not enough to cause pellets to tumble (i.e. disrupt static stability), the disruption to dynamic stability *will* cause inaccuracy.

      Your accurate velocity range thus depends entirely on when the dynamic stability equation is satisfied. For most pellets this region spans between the minimum velocity at which the pellet spins fast enough and the maximum velocity at which it remains subsonic (*WILL vary with temperature), also known as its critical Mach number. Stay inside that region and accuracy will be good.

      It’s worth noting that having a rifle with a very fast twist will enable you to shoot pointy pellets at supersonic velocities, but they won’t go as far before encountering the same transonic dynamic stability problem due to all that extra drag as the subsonic pellets would go before losing too much energy.


  6. I live in Germany, where all airguns are limited to 7.5 joules (5.6 fpe). This is very annoying for long-range shooters and also limits the choice of airguns, as many modls are not offered in low-powered versions. But the big advantage is that the beginners here get an airgun they can actually shoot precisely, while so many Americans buy one of these 200$, 1600 fps bangers, just to become disappointed because it acts like a supersonic water hose.

    Ask yourself if how much power you really need, and have a look at the Brits that hunt anything up to rabbits with 12 fpe. I personally would never sacrifice accuracy or comfort to exceed these 12fpe, unless I had a really good reason for it.


    • Surprising how much keeping the power down makes a rifle much nicer to shoot. A lot more forgiving about pellets and hold. What’s a couple ft-lb difference anyway on the recieving end? Difference in range due to different trajectory? Not much.

      I don’t have any desire to shoot a springer beyond the 800’s range or a PCP beyond the mid 900’s although I have shot both faster than that. That’s still pushing it near the “difficult” point. Less can be easier.

      twotalon


    • Mel,

      I never thought of it from your perspective. You live in a world of constrained velocity. I like in the Wild West — where anything goes. I need to know what lies between us, and you have given me an idea!

      Thanks,

      B.B.


    • Mel:
      I did wonder how we in Britain arrived at the 12ftIb limit for non licenced air rifles and thought
      that 12ftIb was deemed an adequate power level for Mr Average to control vermin at reasonable distances so as not to endanger others.
      Is it possible that our lawmakers and their advisers knew what the ‘sweet spot’ was for a spring air rifle and based the limit on that?
      It would be nice to think they at least got something right.
      DaveUK


  7. B.B., Wow, I think you have asked at least 10 different questions and darn, I have to go to work in a few minutes. Very provocative! Volvo’s comment about the law of diminishing returns most certainly holds true. Changing velocity and caliber and grain weight and sectional density (very important) are so interrelated. And adding PCPs to the mix splits off a whole new set of rules. With PCPs, the faster you try and drive the pellet/bullet, the more air it takes to get each additional FPS. But the energy increase comes at a cheaper air price for heavy pellets , which is something you have demonstrated over and over with PCPs. And that makes sense. But some of the changes seem to be counter intuitive. A weird one that I have run across, and it may only apply to certain platforms, is that in some PCPs the size of the air reservoir can actually affect how efficient the gun is, with the gun being more efficient in its air usage with a smaller tank. In other words, double the tank volume and you don’t get twice as many shots at the same power.
    But back to your original question(s), getting extra velocity comes at a very high price as you move past the 850-950 fps range, especially if the S.D. is high. And then as you approach that alleged maximum velocity for a pcp, the velocity increases are incredibly expensive. Here is something I’d like to drop into the punch bowl: I think you ought to be able to get a higher max velocity out of a special built spring gun than you can get from a special built pcp. What do you think? Yes, you have opened a real can of worms on a very thought provoking topic(s)!
    Lloyd


    • Lloyd,

      It IS a can of worms, but is there underlying structure that can be used to bound reality for the beginning shooter? I think there is, though I think it probably will be different for springers and for PCPs. That structure is what I am looking for, and Mel gave me a clue as to how I might find it.

      B.B.


  8. Morning B.B.,

    I think that twotalon has has hit the pellet on its head with his statements. Look at what bench rest powder burning folks do just for consistency in their reloads: weighing the brass, neck turning, etc., etc.

    Look at what Yrrah does to sort pellets-http://www.network54.com/Forum/79537/message/1189430606/Pellet+sorting+-+inspection+-+batching+-+my+present+ultimate+strategies+for+long+ranging+–

    What are us mere mortals going to do. Perhaps Wacky Wayne, bench rest PCP shooter extraordinaire, will share some of what he does for consistency?

    Bruce


    • Bruce,

      I scanned that report by Yrrah. It is interesting, but far too involved for me to give to a beginner. I need to know the fundamental bounds of accuracy, first, before I start exploring the realm of possibility.

      Mel gave me an idea that I believe could turn into a nice experiment. I will post it in this section and let people comment on it.

      B.B.


  9. BB: On the .250-3000, what took you so long? I’ve had the .257 Roberts, the .25-06, and also .243 in the same model and style rifle(Savage 99) and only kept the .250-3000. It does better than all of them with the 100gr bullet. Only the .257 Weatherby will go faster, but it will waste your money for nothing. On a recent experience for me with springer airguns with less, is this BSA Supersport in .25 like the defective one you tried to test and had problems with. Squirrel season has opened here and I find that this 14 ft/ lbs gun is balanced like you say. With .20.6 gr H&N field target trophy pellets it is accurate and doesn’t waste the energy with pass tru’s like the .177’s in the 17-18 ft/lbs range. Another thing is that it compliments my skill level because of it’s balance. When I’ve been clearing the gun at the end of the hunts by shooting it which for me is when I walk out of the woods behind my gun range. I have been shooting at a target in a field rested position at 25 yards. What I’ve found is that I’ve been hitting it with that one shot , everytime, from the cold gun like you would when hunting. I think that that is another important point about gun selection . The ability to place the first, of any shot on the mark for YOU! almost everytime, anytime. The one shot group if you will . This is after you’ve proven the gun , sight, and load from a bench with ten shot groups. I think that is why shooting and guns are so interesting for me , that and the never ending quest for yet another combination that will do just that. As the gunsmith who owned the store right next to my parents place used to say when someone complained that his gun didn’t shoot where he looked,”that’s why they make different ones”.


    • Robert,

      I really expected you to clean the floor with me after making that comparison between the .250 Savage and the .257 Roberts. I have now shot both of them, plus I have owned and shot an accurate .243 Winchester and all I can say about the .250 Savage is, “Where have YOU been, all my life?” I shot a 0.8″ five-shot group with a 1920 Savage rifle at 100 yards yesterday in gusting winds. Those were the first five shots I ever shot with that caliber in my life and I now own that rifle. Oh, and I forgot to mention — it has a 2-7 variable Redfield scope!

      The .257 Roberts was a Mannlicher 1910 with double-set triggers and it didn’t shoot as well, plus it kicked much harder.

      Why wasn’t I told? 🙂

      B.B.


      • Hi, B.B. Think you could work a photo of your Redfield-scoped rifle sometime? I just love the looks of that kind of scope.

        I’d love to scope an airgun with an old Unertl, Redfield, etc. Again, just for the aesthetics. It’d be a hoot to show up at an FT match with such a thing. Has anybody done this? My wild guess is that these long things need some mounts tapped WAY forward, in an area where most airguns lack sufficient solid steel. Dumb idea? Idle fantasy?

        How are these old scopes in terms of functionality? Dim but precise, perhaps?

        Thanks,
        Jan


        • Jan,

          Yes, I can probably do that. I actually own another scope of that genre. It’s on my .219 Donaldson Wasp, which is a single-shot made on an Enfield No. 5 Jungle Carbine action with an E.R. Shaw barrel. I should shot that rifle, as well, because I bet nobody has ever seen a rifle that has a flat aluminum bar as a forearm! 😉

          B.B.


  10. The genie is out of the bottle. These are topics that could be chewed on for 3 weekends.

    I don’t have time to comment on the firearm analogy other than to say it’s an excellent one.

    In my limited experience with airguns there is a definite point in ft lbs for each caliber. Each time I exceed my limit I regret it. This especially applies to springers. Unfortunately, in my experience, the sole measure in springers isn’t velocity/fpe. You also need to pay attention to spring size, swept volume, tight tolerances of internals (or lack thereof) and mass of the airgun. The HW35 is a fine example of a springer that properly set up uses it’s mass as an advantage. A 30mm tube isn’t necessary as time has proven. The R8/HW50 is proof.

    kevin


  11. BB,

    This whole can of worms is the reason I started reloading for .45acp! Change pistol to match factory loads or change loads to match factory pistol? Either way it’s $1000. I hit that sweet spot by reloading. I suppose I could’ve done the same thing by reworking the gun to handle factory loads, but reloading gives me options for other guns.

    Like Two Talon says, so many factors. And how do you test for that? Better yet, when do you know you’ve reached that point of perfect balance? How long did it take to get the 250 Savage developed?

    Oh thank God it’s Friday, we’ve got all weekend to get to the bottom of this one!

    ka


    • The .250 Savage was developed in 1915 by Charles Newton. He wanted a 100 gr factory load but the marketing types of the period wanted to hit the magical 3000 fps mark, hence the original 87 grain load.

      Given the state of smokeless powder development at the time the .250 Savage probably had the largest practical case for the caliber. The .257 Roberts and .25-06 will easily outperform the Savage. In a bolt action the Roberts will safely drive a 120 grain bullet to 2800 fps, something not possible with the smaller Savage. However that depends on more modern powders that did not exist when the Savage was introduced.

      Paul


      • Paul,

        I have since found other charts in the Speer reloading manual that confirm what you say about the .257 Roberts. But on the range, the difference between these two cartridges is like the difference between an R8 and a Sheridan Super Streak. One shoots smooth and true and the other bucks and snorts to do the same job.

        B.B.


        • BB,

          I agree with that assessment of two different guns behaving very differently. When I was a young whelp of around 25 years old I lusted after a .284 Winchester gun. So I bought a Ruger 77 and proceeded to load the .284 to 7 mm magnum levels.

          That gun kicked the crap out of me and after only 10 shots my whole shoulder was black and blue. I immediately switched to my .243 Winchester Ruger 77 and enjoyed the rest of the day. The .284 got traded that week!

          I was never fortunate enough to get to enjoy shooting any of the smaller capacity .25 or .22 cases as I was young and stupid and went mostly for speed and power. The only .22 round I owned was a 220 Swift in a Ruger 77V. It was a screamer. I chronographed many of my hand loads at or slightly over 4000 fps and the dang thing could consistently shoot the primers out of shotgun shells at 100 yards benched!

          The only thing I ever shot with it was paper, except for one very unfortunate crow that I took out with one shot at a (long) paced 450 paces. Very slightly after squeezing the trigger, the crow exploded into a cloud of feathers. After pacing the 450 long steps I found a large circle of feathers with small chunks of meat strung out in a line about 15 feet long consistent with the bullet path. I did not find any flesh larger than the size of a marble!

          That cartridge is definitely way overbore, but the results when it hits something soft like a cantaloupe or a watermelon are impressive to say the least.

          The only .25 I ever owned was a .257 Roberts and I also owned a 7mm Mauser. After my experience with the .284 I never wanted to shoot any of the harder kicking “big bores”. Largest I ever owned was a 30-06.

          So yeah, if I had the chance to do it over again I would have went with some of the smaller cases like the .219 Donaldson or the 250-3000! If I am ever fortunate to get a place where I can shoot at ranges of 100 yards or more I will still get some thing in that power range.


      • Paul,

        Exactly! Today’s technology has short magnums doing the exact same thing we are talking about. The 300WSM vs. 300Win Mag. for example. BB said it right …”One shoots smooth and true and the other bucks and snorts to do the same job”. How do you know when to stop developing or testing combinations of components? I have to believe the the 250Savage was part lots of targeted experimentation and part chance to come up with such a well behaved cartridge. Relating to airguns, I’d say it’s going to be the same thing, lots of testing and some chance that you “get it right”.

        And I wonder, was the .250 Roberts an attempt to improve the 250Savage or just a similar development that took another route with results only a few years later? (I am referring to Ned’s wildcat version you mention, not the standardized version by Remington some 14 yrs later). Too much coffee for me! I think I’ll go run around the backyard for a few! 🙂

        Should be fun to see where we end up!

        ka


        • KA,

          My guess is the .257 Roberts was Ned’s idea of a better .25 caliber cartridge. It uses the full-length 7mm Mauser case but is more flexible in that light bullets can be driven over 3200 fps for varmint hunting while heavy bullets can be used for deer and even elk. For someone who only has one rifle it covers a lot of game. 7mm bullets were not as readily available back then compared to the .25’s. The 20’s and 30’s was a time of great advancement in smokeless powder technology; larger capacity cartridges became more viable and wildcatters were always looking for more power. The Mauser case was just the next step on the way.

          Paul


  12. I think one of my favorite maxims applies in this instance: “Those who forget the lessons of history are doomed to repeat them”. We need seek no further than the 10 meter match rifle. Virtually without exception they have historically shot in the 500-650 fps range. Did the designers and manufacturers of those paragons of accuracy pick velocity randomly or did they design their flagship target guns to operate at the speed that experience had proven that gun and projectile would be most accurate?
    Current ‘wisdom’ makes it abundantly clear that some are “doomed to repeat the lessons of history”.
    Which leads to my all-time favorite from Rob’t. Heinlein—TANSTAAFL! Tom


    • Tom,

      I thought about that when I wrote today’s report. But air rifles that shoot even faster than 10-meter rifles do very well, as well. So I want to know what the safe zone is, so I can point it out to new airgunners.

      B.B.


  13. “Mary Kulesa Geraci is this week’s winner of Pyramyd Air’s Big Shot of the Week on their facebook page. SHE’LL receive a $50 Pyramyd Air gift card.”

    Congratulations Mary. Great photo.


  14. I have an unrelated (or IS it?, LOL) question regarding the universal and enduring love affair airgunners have with the classic Sheridan Silver/Blue Streak. It is B.B.’s desert island gun, if I remember correctly, and many times I have read posters here and elsewhere declare that their classic-era Streak is the last air rifle they would ever part with. Granted, its characteristics make it an excellent survival tool, but there is an unmistakable romance/mystique surrounding this airgun that other guns do not have, even other air rifles that are similar to the Streak.

    What I rarely find, however, is a specific list of characteristics that make the classic Streak such an icon.

    Yep, powerful for its size, multi-pump/multi-power capability, made in USA, etc., but why is a classic, Racine-era Streak more worshiped than, say, a classic model Benjamin in .22? A Crosman .22 pumper of the 100 series?

    Perhaps I’m curious about this because while I have no relatives in Rochester, I had (all passed away now) cousins and uncles who worked in the Sheridan factory and one distant cousin who briefly worked in the Benjamin factory in St. Louis.

    I’ve had Crosman, Daisy, and Benjamin pumpers over the years, and the one pumper of mine I’d never part with is actually a Smith & Wesson 77a. But what, specifically, have I been missing out on by not having a classic Sheridan?

    Thanks in advance for your thoughts,

    Michael


    • Michael,

      I used to wonder the same thing, and back in the 1980s and earlier, I think it was the superior Sheridan ammunition that kept that brand of pumpers ahead of the crowd. But when Crosman launched the Premier line in the 1990s, they did away with that advantage, and now a Benjamin 392 is just as fine a shooter as a Blue Streak. Both love their respective Premier pellet.

      The old cylindrical Sheridan rounds can’t seem to keep up — and I know I’m going to catch flack for saying that.

      Perhaps we need to do a test? 🙂

      B.B.


      • Great subject for the weekend, BB! I’d have to agree, a test is in order. Sure would help me out, anyway. I have always owned Crosman pumpers. Back in the 60’s, my friend had a Benjamin .22 that I liked. I always wanted one, but we grew apart and time slipped away. I never did get one. I knew I liked the .22 and had heard about Sheridans, which just added to my indecision so it never happened. Those 2 are still bumping around in the back of my mind. I still have Crosman pumpers, and am fortunately the owner of a few nice springers, but no Benjamins, Sheridans or any pcp’s. So while drooling over new pcp’s and older 55 Tyroleans, I still think I need to get this pumper thing out of my system. So, maybe a test is in order to help me (and others) make up my mind on which one to look for. And while you’re at it, maybe you could throw in those cylindrical rounds…. 🙂

        /Dave


  15. B.B.,

    I just did a quick check of Pyramyd Air’s .20 pellets, and Beeman Kodiak Extra Heavies have a perfect 5 star rating from 5 users, Crosman Premiers have what could be considered a statistical tie at 4.5 stars with 5 users, and, drum-roll, Benjamin Cylindricals have a perfect 5 stars from EIGHTEEN users. B.B. you were right to predict a lot of flack. Time for the Kevlar jacket and helmet.

    Of course a large number of airgunners are traditionalists and remain nostalgic of their formative years, etc., but airgunners are also hungry for innovation and will quickly embrace any new thing that undeniably WORKS.

    Hmmm. B.B., if you were to do a comparison, I think it would have to be a multi-comparison. A rocker-safety Streak using all three of the above pellets vs. a Benji 392 (PA?) with the same three pellets. Obviously there is a caliber difference, but the pellet makers have tried, it seems, to make .20 pellets in the same weights as their .22 models.

    Might there be magic in the .20 diameter? I would be interested to see what differences exist between the two guns’ accuracy, velocities (and not just at 8 pumps, but also 4 and 6 pumps), difficulty of pumping at each stroke, and trigger pull and characteristics. Certainly fit and finish is a consideration, too. That is all with the knowledge that the classic Streak and the classic Benjamin are two different beasts.

    A comparison of today’s two rifles might be interesting, too, but for different reasons. A few glances at the Pyramyd Air’s webpages for Benjamins and Sheridans show that there is precious little difference between them today, except, interestingly, slight differences in weight and velocity. The one big difference is that the Sheridan is $30 more than the Benji. What does one get for that extra $30? Name-cache? The “benefits” of a half-pound heavier rifle with 10 fewer fps? The need to spend more per round of ammo?

    Well, I guess the whole, “I have a Sheridan” feature has genuine, if not-measurable, value.

    Michael


    • Oops. I now see another clear favorite among the .20 pellets on the Pyramyd Air site: JSB Diabolo Exacts have a perfect 5 score from 19 users. THAT’S a ringing endorsement.

      Michael


    • Michael,

      I wasn’t referring to the modern pellet that Benjamin calls the cylindrical. I meant the original Sheridan cylindrical pellet that was sold 30 years ago and was really cylindrical in shape. At airguns shows you can see guys buying these old plastic boxes (yellow) of Sheridan pellets because they are convinced they are the best. I have no experience with the modern pellet Benjamin sells as thew cylindrical.

      B.B.


  16. 4946.1

    I have Mac1 Hunter #14 which has a 20 caliber barrel. I am at least the third owner of this gun. This past weekend I had my first opportunity to shoot the gun a 100 yards. I was shooting across a bright sunlit field towards a dark colored target board in the woods. This allowed me to see my pellets very well. The wind was very light.

    I had three different pellets with me, 13.5 gr. JSB Exacts, 11 gr. Beeman FTS, and 14.3 gr. Benjamin Cylindricals. All three pellets spiraled in what looked like large spirals. The Cylindricals spiraled the worse, the Exacts almost as bad, and the FTS a little less.

    Yesterday evening I shot a few shots of each over the chronograph. The JSB Exacts averaged 875, the FTS 925, and the Cylindricals 835. In the past I have read of too high velocity causing spiraling but I don’t think these velocities are that high. I don’t see any crown damage or signs of clipping on the muzzle brake.

    Any idea what might be causing the spiraling and what I can do to prevent it?

    Thanks,
    David Enoch


    • David,IMHO,it is time to clean the barrel.I say this while thinking about a GREAT illustation done by Ted in Madison in one of his videos(some of the best I’ve seen).He shot slo-mo to show the offensive spiralling…..then cleaned the barrel.The results were very convincing.Please check it out,and keep us posted.


  17. Everybody,

    Here is the germ of an idea I got when reading Mel’s comment. What if I used the Whiscombe to represent a mega-magnum .177 air rifle and set it up to shoot above 1,100 f.p.s. with lighter pellets? I could test it for accuracy with several different pellets, maybe even including some I buy at Wal-Mart.

    Then I could drop the velocity to something around 900 f.p.s for these same lighter pellets and test it again.

    Then I could drop it again to something under 800 f.p.s. and see where it is, in terms of grouping ability.

    One problem with this test is that all the time I would be shooting the same powerplant — a Whiscombe. If I were to try this with a real mega-magnum, the internals would have to be changed to drop the velocity, but I would be doing it with transfer port limiters.

    I want to begin with a spring gun, because I think it is unreasonable to think that a new buyer will go straight to PCP. I’m also leaving out CO2 and all other powerplants, because they are either not flexible enough for me to test this the way I want to, or, as in the case of CO2, they are really only capable of one power range unless you make major modifications.

    The goal of all of this is to be able to tell a new airgunner absolutely that he can expect the best accuracy an airgun is capable of if he gets a gun that shoots between XXX f.p.s. and XXX f.p.s.

    I know that many airgun manufacturers read this blog to learn what their market wants to buy, and if I was able to start making supported claims like, “A .177-caliber air rifle will be most accurate between 600 f.p.s. and 800 f.p.s.” then they would consider making guns that do that.

    B.B.


    • BB,

      sounds like a marvelous experiment. I have not heard of anyone ever doing that as respects accuracy. I seem to recall the Cardews did something along the lines of different velocities for transfer ports but they did not go in the direction of how the pellet behaved iro accuracy. I’ll have to review my book. I will be looking forward to the results of your experiment.

      Fred PRoNJ


    • B.B.,
      Here’s an interesting scenario. Imagine a pellet that comes in two weights, one light and one heavy, but that is otherwise identical. Suppose that there exist an air-rifle that shoots the lighter pellet optimally, accuracy-wise, at some velocity. Now suppose that an identical rifle is modified to shoot the heavier pellet at the same velocity that was optimal for the lighter pellet. What might we expect in terms of difference in accuracy?

      I bring this scenario up because I know that we often find that an air-rifle that shoots light pellets poorly at a high velocity will shoot heavier pellets better. The reasoning is usually that the improved performance is simply because the velocity was brought down by the extra weight. I’m just wondering if difference in weight can adequately be the only explanation because sometimes the pellets length, and other design details, are significantly different.

      Victor


      • Victor,

        But if the same pellet weighed two different weights it would be the same pellet, would it? We have such a pellet pair. The Crosman Premier lite and heavy in .177. But they aren’t the same at all. The heavy is longer, and therefore flies differently than the lite.

        However, what you say does have something to think about. How one gun will shoot a heavier pellet better than a light pellet.

        But That is too complex for me to model. If I do I end up with a one over the world relationship — which is where I am right now. I need to find something that is broader and will work with every airgun.

        B.B.


        • BB,
          Yes, it does seem that narrowing in on a range of pellet weights to test each caliber for accuracy vs velocity would be very important. And I would think that that would be by whatever the most popular pellets or weights for each caliber would be. Pelletman’s listing of preferred velocities for different pellets show that the heavier (usually meaning “longer”) a pellet is, the more velocity it needs to keep it accurate. That certainly makes sense and is supported by the various barrel twist rate calculators. And if this testing and the resulting info really is aimed at new airgunners, maybe the pellet selection should start with what folks can buy off the shelf locally. Or I wonder if PA has a way of looking in their sales database and determining what pellets first-time buyers on the site order? By the time some is making their 3rd or 4th pellet order you probably can’t call them “new airgunners” anymore.
          Lloyd


          • Lloyd…..

            I see a problem involved with attempting to come up with database info on best pellets.
            Some people are attracted to junk pellets by the hype, or because they look pretty, or the flashy packaging. Some will stubbornly shoot something that does not do well for a variety of reasons.
            The whole thing gets to be like reading reviews. What are they telling you, and what are they NOT telling you? And every gun is different too.

            I spent a bunch of time running pellets over the chrono to look at velocity spreads and FPE. Anything I came up with is only relevant to the particular rifles tested (springers).
            The lower powered rifles liked lower weight pellets best for best FPE (efficiency) while the mid powered rifles liked the mid weight pellets better. Clearly there is a relationship here between pellet weight, power level, and efficiency. It stands to reason (maybe) that the more efficiently a power plant is running that more energy is used on the pellet, and less is used to bang the gun around.

            If you can find a pellet in the most efficient weight range that has the tightest velocity spread, then you have some chance that it should be accurate. But what if it is NOT accurate for some reason?

            You can also find that some rifles will shoot very well with pellets that are noticeably less efficient because they are either too heavy or too light. Some like two or more considerably different pellet weights, one of which may be “right” by FPE and the other “wrong”. Or BOTH wrong.

            Then you find pellets that SHOULD be in the groove for accuracy, but SIZE difference kills one (or both)for accuracy.

            I think I worked my way off the topic. Must have a beer.

            twotalon


            • I agree that this a tough one to bound in a way such that you get some meaningful results. As you pointed out, the variables seem almost unlimited. I think I will listen and see how this one plays out.
              Lloyd


              • The biggest danger is in getting fooled by something that gets overlooked. Like the way the news media and the government handle statistics. They show you the “facts” but don’t tell you everything….and they do it on purpose. Easy to get fooled even if it is not intentional.

                The way I see it, unless you want the most velocity or FPE, you should just find a variety in what SHOULD be in the right weight range with a fit that seems about right and try them. Don’t overlook going outside that weight range unless you see a need to. Find a pellet that is PRACTICAL for distance and wind conditions. You may have to settle for second best under perfect conditions when you have to apply it to real life.

                twotalon


          • Unfortunately, depending upon availability, the “first time” buyer may end up with sampler packs (and I’m ashamed to admit I still haven’t used up packs I’d bought in the 80s! A Dynamit-Nobel era RWS .177 sampler: MK, Hobby, Super-H-Point, Super-Point, and whatever the domed pellet is called [100 each] and a pair of Beeman samplers in .177 and .22… 50 each in domed, pointed, hollow point, wadcutter, cleaning wads (and two weights for some of those))


    • Now you are living in my world…I’ll be curious if you get the same results as me…

      Regarding: “I know that many airgun manufacturers read this blog to learn what their market wants to buy, and if I was able to start making supported claims like, “A .177-caliber air rifle will be most accurate between 600 f.p.s. and 800 f.p.s.” then they would consider making guns that do that.”

      I doubt it,….because from a manufacturing standpoint, you cannot gaurantee a specific pellet will be accurate across all guns you manufacture through that 600-800fps range… The overall question is “with what pellet?”.

      Its been my experience every airgun is different. I have some .177 caliber airguns, but mostly .22caliber. Alot of modded guns use crosman barrels (and power adjusters), and a pellet in one gun may not be as accurate in another gun at the same speed.

      Plus most airgun manufactures claims are overstated anyway. I do like guns that boast and actually meet their claims of 1000+fps,…I get excited because I know 9 times out of 10, I am going to be able to shoot a heavy pellet at 800+,…and if I choose the right pellet (9 times ouf of 10 JSBs), I’m going to have some good accuracy.


    • I know that many airgun manufacturers read this blog to learn what their market wants to buy, and if I was able to start making supported claims like, “A .177-caliber air rifle will be most accurate between 600 f.p.s. and 800 f.p.s.” then they would consider making guns that do that.

      Of course that then begs the question of what pellet weight range is needed?

      After all, stuff a magnum weight pellet into a spring rifle and you’ll likely be able to produce such a “slow” speed range. It may even be accurate. But will it be efficient? (Blast — I got over “efficient” cleaning out my backpack last week, and seem to have removed my “one-shot” velocity test spreadsheet output).

      On my spreadsheet doing one chronographed shot each with a range of pellets I’ve seen where both the .22 RWS m54 and the .177 Gamo NRA 1000 Special (Shadow variant I believe) have a zone in which pellet weight and corresponding velocity change leaves the muzzle energy fairly constant. Get outside of that range and the muzzle energy drops significantly. [Note: I’ve not shot for usable accuracy yet — I was happy if my 25yard sight-in was in the black*; I don’t recall which targets I was using — maybe some of the 10m multi-bull targets that fit the “silent” trap, since I had minimum 4X scopes a 10m target at 25 yards is still larger than open sights at 10].

      And of course the Condor tended to the opposite, with the heaviest pellet (without changing thumbwheel) showing the greatest energy even if the velocity was that of a bowling ball… (hyperbole, folks)

      * Only thing I’ve done “one hole” groups with has been my US Shooting Team edition of the Daisy 953 [basically what is now the 853 with a 953 action/barrel], at 5m [front door to hallway closet]


    • Your Whiscombe would be a great test bed, BB. The power plant stays the same except for adjusting velocity, but more importantly, the barrel stays the same (no length, twist, or crown variations from switching guns). And you’re using a known, accurate gun, so that variable pretty much gets tossed out. After seeing your group with the HW55, I think your accuracy will be a constant, so we can count out that variable too. Should get a good, repeatable result for the velocity experiment, unless the weather doesn’t cooperate.

      /Dave


    • B.B.,

      Interesting experiment that you proposed.

      I believe it’s difficult to translate ideal velocity to pellet caliber and weight since the type of gun plays as much or more of a role in accuracy especially in airguns. Your Whiscombe is the perfect testbed when the results are prefaced with “The least hold sensitive gun with the best barrel was used in this test.”

      Most inexperienced airgunners would benefit from the knowledge of a test that shows shooting a pellet at 1300fps doesn’t aid in accuracy but they also need to know that many airguns with loose fitting parts and lightweight stocks, even shooting in the ideal caliber and velocity, won’t necessarily be easily accurate.

      Your example of the HW35 in your article above is a very good one. Push it too far and you’ve lost what you had. This also prompted me to write this:

      http://www.network54.com/Forum/79537/thread/1318205735/HW35

      kevin


  18. David,

    Because I’m from the Chicago area, I have a soft spot for Jim McMahon. While the Bears have running backs and middle linebackers galore in the HoF, a decent QB on the Bears roster is as rare as hen’s teeth. McMahon had a weak arm, a slow release, and his passes wobbled like they were drunks on Rush St. And yet, they usually hit their mark somehow.

    That over with, spiral or not,how was the accuracy on the target?

    Michael


  19. B.B.,
    This is an excellent blog and topic of discussion. You might recall that I was asking about this very thing last week. I know so little about guns, ammo, and ballistics that I couldn’t really begin to address this from my limited knowledge base. I’m a simple paper puncher (a simpleton of sorts :)). In any case, while the responses here are a bit overwhelming to me, they are impressive and worth consideration. I’m humbled and impressed with our group here. Thanks for another informative and insightful blog!
    Victor


  20. Great job, Mary, in today’s photo. I’m much larger than her, but I find that holding the Daisy 747 to be a chore. She’s using two hands, but still that is stout work by her.

    As to optimal caliber and load for firearms, I have no doubt that there is such a thing. Case size is certainly one variable. I believe that this is the explanation behind the slight superiority of the .308 over the 30-06. Otherwise, in the large, one generally finds rifles converging towards 6 mm calibers for both target shooting and knock down power (for military applications anyway). Of course the optimum will change for the application, but 6mm seems to keep popping up.

    As to airguns, the big limiting factor seems to be the fact that there are only 2 major calibers in comparison to a veritable zoo for firearms. Why is that? I would be surprised if .177 and .22 happen to be the best choices, so that right there might be the limiting factor. Within these two calibers, I expect that vast experience has already found the answers which B.B. mentioned–500-600 fps for springers in .177–and about 800 fps for springers in .22. How interesting that my B30 at 900 fps is actually overpowered. But it is steady as a rock and much less hold-sensitive than my IZH 61.

    Mike for my M1, I’ll try the recommended load then consult the gunsmith. And for the .45, I’ll try jacketed hollowpoints and then see.

    Victor, regarding reality shows, my sense (from very indirect observation) is that they now exist in a realm between reality and script. On the one hand the performers say that they forget that the camera is even there, and on the other, their acting has become almost instinctive. There’s a character on the reality show, Keeping Up With the Kardashians, named Scott Disick who is kind of the villain of the show–an irresponsible playboy and a drunkard. In one episode, the Kardashian mother was kicking him as we was wrestling with another guy in a drunken frenzy. Scott was in rare behavior and managed to get himself dumped on the same show by his pregnant girlfriend Courtney. As he was listening to her break-up message over the phone about how she never wanted to see him again, he looked slightly annoyed. And sure enough he won her back over by the end of the show. Anyway, I don’t believe anyone could have scripted that expression on his face during his rejection. It was priceless.

    Maybe I’m experiencing a little of the Top Shot dynamics already. At the range, there was the usual complement of people with AR-15s spraying the targets from a rest. I, on the other hand, garnered a certain amount of envy with my rifles. The severe German geometry of the Anschutz really stood out as did my M1. Little kids were picking up the used clips for me. It’s plain, they thought I was neat… 🙂 But one disadvantage to having an Olympic rifle is that people ask to see your target… 🙁

    As to the effect of reality shows on social consciousness, I’m actually something of an optimist. One of my fascinations is the terrible quality of life in earlier times. There is a YouTube series on this subject called the Worst Jobs in History. A fairly cursory look at history tells me that being born in just about any other time period would be just about unimaginable from the Roman times with mass crucifixion; to the medieval period with people dropping dead in the streets or being whipped naked through streets and then hanged, drawn, and quartered with their insides pulled out before a cheering populace; or the Early Modern period with bulls, bears, and dogs ripping each other apart as crowds guzzled food and beer, to the squalid tenements of 19th century America full of disease, crime and alcoholism; the multiple atrocities of slavery; the Wild West, lynch law…. I don’t know that public sensibility from previous times, even in the form of its popular entertainments, has much to boast of. What I think is taking place in reality shows and the related internet phenomenon is a sort of ratcheting effect. Old standards of decorum in media are being stretched as the mass population gains access to them, but as they come online, there is a certain tempering effect. The brawling and crude language is more vulgar than truly immoral. And most reality shows have a sort of moral message, cliched though it might be. So, I think you can argue for a sort of spiraling forward advance. It’s not unlike certain readings of the education system where standards seem to be going down because the system is getting more accessible to people who otherwise wouldn’t have been educated at all. A bold claim on my part I know that certainly does not apply to everything out there for consumption. But we will see.

    Matt61


    • Matt,

      Always enjoy reading your comments. Helps me realize my inadequacies in transferring thought to paper (or monitor?)! I especially enjoyed your synopsis of cultural progression from the earliest of times to present! As for “reality shows”, Top Shot has been great this season. I admit that the sniveling ex navy seal, Jake (?) has added a certain degree of entertainment for me. I would really like to see the christian camp counselor beat him in a one on one elimination! Oh, nothing like admitting I’ve gotten wrapped up in the drama of the show!

      ka


      • lol its the drama that gets you
        i think TOPSHOT is a misnomer, the one that wins isn’t always the best shot. its almost like the island show called survivor, but this time while shooting targets. you have to play politics with the other contestants, to help you stay on the show. i hate to see some of the best shots get eliminated by not doing well in an archery elimination, or canon shooting contest.
        if they were truly concerned with finding the topshot, they would hold a shooting contest in each category for all contestants, each day/episode, and at the end of the series, the one with the overall best score wins, but that doesn’t make for good television, drama sells.


      • KA

        My favorite season of Top Shot is the first season. This was the one where the self-appointed expert, who was able to hoodwink the entire team by sheer confidence, got elected team captain. He then proceeded to get eliminated in the very first round due not to politics, but his clear inability to hit any targets.

        The kid, Kelly, was elected to almost every elimination round because no one wanted to be outdone by someone so young, or maybe it was the of producer-scripted drama. In spite of sniveling conspiring, and having to go to just about every elimination round despite having performed well for the team, he lasted to the very last episode where he was finally outdone.

        To me, he will always be the Top Shot. He overcame the challenges, and what must have been overwhelming frustration that his ‘team mates’ elected him for elimination for performing well. He kept his cool, and hit his mark anyway.


        • S-Lead,

          I agree with you.

          Second season I thought was kind of dubious that 3 members of the red team admitted they conspired at the beginning to make sure they remained.

          I always thought Jamie of the red team, got the short end of the stick in the second season. I thought the husky Marine Sniper of that same season was sort of a punk.


        • SL,

          I agree wholeheartedly, HOWEVER, I can’t wait ’til the episode Jake gets the axe! It REALLY NEEDS to be a humiliating experience and not one that he gets beat by someone he considers an equal. I still laugh at the first couple of episodes this season where he has them doing drills, set up obstacles and pointing of broom handles! Ha! Ha! I loved it when he got all but-hurt over being nominated for exclusion!
          Now, that said, Let’s remember that this is only a “reality” show to capture the attention of all of us that ignored Survivor.

          Addict, Yes, If it were really a show about top shots and based solely on top shooting it would be just another of thousands of shooting matches and would probably hosted by R. Lee Ermey and not the self conscience smiley macho guy!
          OORAH! DROP AND GIVE ME, MAGGOT! 🙂

          ka


          • Ya think he’ll go out? Could not happen to a more qualified guy. I looked him up on Google; doesn’t seem as if fitted in at USNA or SEAL Team 8 any better than at the U of New Hampshire and a half dozen other football teams. But they may tease the audience and keep him.


        • Yup. If top shot meant the guy most likely to hit his target, Kelly the Kid was definitely the best. But “for some reason” the hyper-alphas wanted him gone.


        • SL,
          I thought you would be interested to know that Iain Harrison (the winner of season one “Top Shot”) took first place in the National Defense Match (NDM) at Camp Perry in August this year.
          Caveman


          • Anonymous

            I AM interested to know that, thank you! I am very happy for him. Next to Kelly, Ian was my favorite of the first season, and a damn fine shot to boot.

            I also have a huge amount of respect for the guy in the 2nd season who missed on purpose in the final round so his friend could win, because his friend really needed the money, and he just wanted to play the game. He was cocky, and definitely the alpha type that usually rubs me the wrong way, but he really showed the quality of his character.



      • She’s holding a Baikal, and it makes holding a Daisy 717/747, uhm… childs-play…

        I still have to take a rasp to mine to relieve the channel for my trigger finger, along with a dish for the knuckle of my thumb. How she’s managed to get that much finger on the trigger (and yes, I have mine slid all the way back) is beyond my… She’s even got her thumb wrapped over the hard edge of the grip rather than along the thumb-rest groove.


      • She looks like she’s getting more finger on the trigger than I do with mine. I think that’ partly due to how the trigger is canted to the right for right handed shooters. I’m left handed so the trigger is canted away from my finger. She’s lucky she’s right handed or she would not be able to even hold those grips. BTW, they are made out of wood so if she is really going to be a serious 46M shooter they can be shaped to fit her much better. There is plenty of room in those grips to work with.


    • Matt

      You are quite right about the plethora of powder-burning calibers vs. available airgun calibers, but then again that might be a blessing, no? I would hate to have to provide myself with anymore ammo stockpiles than I already have. I am running out of room.

      On that same vein, I think the .20 cal is much undervalued. Despite being a great caliber, most manufacturers ignore it completely. Pellets cost the same as .22 in most cases, and have fewer options available. To me, it is like Sony’s Betamax. Despite superior technology and a better picture, it lost out to VHS.

      BTW I don’t think I was harsh with my evaluation of Haily Walcutt. She seems very nice, and she isn’t hard to look at. All I am saying is that she is not a natural as Crystal was. Crystal seemed to be at home in front of the camera, and to genuinely enjoy airgunning to boot. She is also drop dead gorgeous and can hypnotize people with her deep blue eyes, but I digress. I’m just thankful for a season 3.


  21. “Sure, you can get the .177 Bow of Hercules if you want, but just remember that the immutable laws of airgunning dictate that the most accurate air rifle will always be….”

    … one that you don’t own

    {Obviously time for me to go to lunch while the horde sharpens their scythes, hoes, and pitchforks}


  22. I saw a great explanation in an old post, saying 1 fpe per pound of rifle resulted in smooth shooter. My guess is that it also matters where the rifles balance point is, and that is why under levers are less hold sensitive than break barrels.


    • That would imply I should be shooting 32gr Eun Jins from my .22 RWS m54 (since Kodiaks started to pull it down to around 12-13ft-lb; 14-18gr were in the 18ft-lb range).

      I suspect accuracy would stink, if 9ft-lb of the air impulse was basically being applied to deforming the pellet skirt and not in acceleration down the barrel. Conversely overly light pellets might zip down the barrel and out without achieving maximum impulse.


  23. Frank and everyone talking about the maximum range a battle rifle can be accurate by reading the rear sight graduations,

    Going back to World War I, the armies of the world were experimenting with many new things. Two of the big ones were smokeless powder that was in its infancy and the machine gun.

    The machine gun cased troops to mass in protective trenches (linked foxholes), while smokeless powder made it possible to shoot much farther with man-killing accuracy. The rifle sights on those rifles (take your pick which country — they were all the same) were left over from the black powder days. Our 1903 Springfield, for example, was using the same Buffington-style rear sight that came into being in 1884, when Col. Buffington designed it for the Trapdoor Springfield single-shot rifle. All they did was engrave new numbers on the sight slide because the .30-caliber 1906 cartridge shot so much flatter than the old .45 caliber government round (.45/70).

    So — having these super-long-range sights on all the rifles, people had to figure out something to do with them. Plunging fire became the rage of the day, and books were written about it. You didn’t shoot at targets anymore. You shot at points on a map. Cones of fire became the target, rather than individuals. And since they needed justification, they used the trenches as the “reason” for developing these tactics.

    Did these tactics work? Of course not! Does a military rifle shoot 1,000 yards (to say nothing of 2,900 yards) accurately? Of course not. But that didn’t stop the arsenals of the world from building their rifles that way. It was a fantasy that many people bought into. We still see vestiges of it today. My Guidebook for Marines has these tactics in it and it was written in the 1950s.

    So forget what is engraved on the rear sight of a battle rifle. Because it just doesn’t work the way the engraving seems to imply. You’re good out to 300 yards with a good 7 mm to .30 caliber/8 mm and to 200 yards with a modern .22. After that it’s spray and pray. One soldier in a thousand will be able to push these distances out farther and most of the time he is drafted as a sniper, if the service he serves recognizes his skills.

    There is a corollary in modern tanks, or at least we had one up through the M60A3 series. Our coaxial machinegun is mounted to fire in parallel with the main gun, but of course not to the same distance. A main gun can drill a target several miles away; a coax machine gun is limited for maybe 700-800 yards. We didn’t use a sight for the machine gun. We used a ghost ring that was called an infinity window. Put the target in the window and pull the trigger. Hopefully some of the bullets will hit whatever is inside the white ring.

    B.B.


    • I just got a very odd result while testing a Marksman 70 in .22 over the chrony.CP’s are making a little over 14 ft-lbs.JSB Exact jumbo heavies are actually shooting 20fps faster,and making a whopping 19.8 ft-lbs……even though they feel nearly identical when loading.Very interesting.


    • BB,

      It has always seemed to me ridiculous to design infantry weapons for an accurate 1,000 yard/meter range. It is almost impossible to see an individual in camo at that distance, and essentially impossible for the average grunt under the stress of incoming fire to hold a rifle steady enough to hit the target even if he could see it and distinguish it. You’ve handled these weapons; I haven’t, so if I’m wrong tell me. As you said, those few who can do it are called snipers. And while a sniper has lots of stress, much of the time he can set up without being shot at. After a round or two, that’s no longer the case.

      pz


    • So forget what is engraved on the rear sight of a battle rifle. Because it just doesn’t work the way the engraving seems to imply. You’re good out to 300 yards with a good 7 mm to .30 caliber/8 mm and to 200 yards with a modern .22. After that it’s spray and pray. One soldier in a thousand will be able to push these distances out farther and most of the time he is drafted as a sniper, if the service he serves recognizes his skills.

      Fun trivia about sights on battle rifles: The HK-91/G3 peep sight drum has three peeps at 200, 300, 400 meters (why am I suddenly visualizing marshmallow easter chickens as bright colored targets on a desert range?). The fourth position is just a rough V notch meant for short range (<150 meters). Though the three peeps do straddle your 300m value for 7-8mm cartridges.

      There is a corollary in modern tanks, or at least we had one up through the M60A3 series. Our coaxial machinegun is mounted to fire in parallel with the main gun, but of course not to the same distance. A main gun can drill a target several miles away; a coax machine gun is limited for maybe 700-800 yards. We didn’t use a sight for the machine gun. We used a ghost ring that was called an infinity window. Put the target in the window and pull the trigger. Hopefully some of the bullets will hit whatever is inside the white ring.

      Hearsay, possibly someone’s interpretation of the rules from the old Avalon-Hill (or was it 3M at the time) Arab-Israeli Wars game — Israel was using, as I recall, US M60s, and essentially had line-of-sight cannon — if they could see the target through to bore, they could hit it. The Soviet design Arab tanks needed to range-find and adjust for shell trajectory. I doubt it was quite that simple.


    • BB:
      I’m just looking past WWI for some clues on this subject.
      A lot of the ‘modern’ long range rifles were designed and adopted at a time of European colonial expansion(late 19th,early 20th century).
      When you had mass hordes(a large target) of natives charging at ‘the thin red line’.
      If you could start popping off these folk at 1000 yards as opposed to 300-400.
      Less chance of being overwhelmed by shear force of numbers like what happened in South Africa to 1200 British troops (armed with Martini Henri’s) by the native Zulu’s.
      The Maxim machine gun was I believe bought by the Euoropeans for this purpose as well and was indeed used to great effect on the natives in the Sudan by the British Army for example.
      These weapons really turned round and bit us in the butt when WWI broke out though.
      DaveUK


      • DaveUK,

        Yes. It seems that we always start the next war using the successful tactics of the last. Sometimes, if there has been little time since the last war, this works. But if the circumstances have changed in some major and fundamental way, it doesn’t work. Hence the classic failure if the Maginot Line. Would have been perfect for WW I, but not for a battlefield with fighter aircraft, bombers and tanks.

        B.B.


      • Dave,

        If the massed hordes were charging, did the defence have to shoot aimed fire at each person, or was the point really more to have a ‘solid’ wall of heavy bullets with lethal energies at 1000 yards?

        Being simple, how ‘big’ does a man appear at 1000 yards?

        Two yards high divided by 1000 yards is a tangent of 0.02. About 0.75 degree, or plus or minus .375 deg in the vertical and about plus or minus .1 degree horizontal.

        At ten meters a competent shot can hold the 9-ring, about (I’m guessing) 6 mm all told, including the pellet diameter, so an angle of 6/10000, or .0006 for the tangent — much smaller! Close to .03 degree. Questions then of skill, rifle maintenance, and ability to perform under mortal stress. Give me a machine gun and artillery!


        • PeteZ:
          Yes I believe throwing up a wall of solid lead out to further distances was the aim,not targeting individual soldiers.
          It is just me floating a boat but the weapons and tactics seem more geared up for defensive actions conducted by an outnumbered force.
          Which of course soldiers of empire always were at the time these weapons were first designed and built.
          These empire building weapons and ammo were then made(for want of anything else) in such vast numbers during WWI,that Britain for example,was stuck with them till the 1950’s.
          1000 yard sights and all.
          Nothing set in stone though Pete,I just like theorising after a cup of coffee 🙂
          DaveUK


  24. Fast Neutrinos: A Break from Airgunning

    My son’s back from Japan, and I’ve had a chance to talk to him for a bit. The American-based and Japan-based groups will be getting down to business trying to replicate the CERN results as quickly as possible. For the moment the Fermilab people will have more sensitivity, but the Tokai, Japan lab will overtake as it recovers from the earthquake and comes to full intensity.

    Everybody is taking the CERN faster-than-light result seriously. The group did a very hard experiment, did it pretty carefully, has looked at the obvious possible problems and has addressed them. And in proper science fashion has been extremely open about what they have done. The current betting (if the effect holds up is that the neutrinos have been able to enter a new dimension and take a shortcut.

    It’s impossible to explain that in words for our 3-D universe since we don’t have the word or the sensors to look at our universe from outside. But in 2-D there’s a good analog.

    Take a piece of typing paper. Make an ‘X” at the center of the top and another one at the center of the bottom of the page. The distance between the two dots is (US standard 8.5 x 11″ paper size) just a little under 8.5 inches. Fold the paper in half so the marks are on the outside. The two Xs are still 8.5″ apart because you still have to measure in the paper and go around the fold. Consider an ant crawling from the top “X” to the bottom. How far does it go? 8.5 inches. Now imagine just a little hole in the paper such that just the right ant at just the right place and speed can go through directly from one sheet to the other without going around. Has to be a tiny hole so it’s hard to find it and hard to go through. Most of the time the ant will never hop through the paper, but once in a while it might take a shortcut through the new dimension.

    People think this is one possible explanation. Cast in math that’s beyond me, for sure. And probably specific to type of neutrino and neutrino energy.

    Note that it does not invalidate Einstein for any ordinary case and situation! Charles Krauthammer’s crazy column to the contrary.

    But I still bet on an experimental problem.

    pete


    • Pete,
      Thanks for that update and the descriptive explanation. You are so right about how our lack of words and personal experience limit our ability to comprehend what might be happening in that experiment. I am still stuck on comprehending the vastness of the universe, the continually expanding universe, and the big-bang theory. It is all fascinating, but I do not keep up with it regularly. For me, it would be interesting (helpful?) if a probability of “lasting validation” could be applied to some of these recent (past 50 years?) experiments and theories and discoveries. Odds makers for the scientific community?
      Lloyd


    • Thanks for the update from me too, Pete. I hope to see confirmation of the experiment. As you said, it won’t invalidate Einstein. He may have just scratched the surface of explaining the universe. For me, being a practical man, I hope these neutrinos will find me a faster way to work in the morning…

      /Dave




  25. Wow! It is amazing how many rabbit trails this blog can chase down sometimes!

    As to neutrinos, how much FPE do they have? And how accurate are they? After all, “What good is 500+FPE if you cannot hit what you are shooting at?”.



      • As you may guess from my question, I for one am not that impressed with speed and power. I would rather discuss MOA than FPE. But I do realize a certain amount of FPE is necessary to achieve my desires. 1 MOA at 50 yards excites me! If it only requires 12 FPE at the muzzle to accomplish this, that is wonderful. In fact, it is likely the case because you have less recoil, vibration, etc. to deal with to make 1 MOA possible.

        As B.B. pointed out at the beginning, the .250 Savage is a small cartridge (relatively speaking) achieving the same results as larger cartridges. The marketeers have learned to appeal to our egos with the bigger (or faster) is better. As B.B. has also pointed out previously, the diabolo is a subsonic projectile. To achieve any type of accuracy with airguns we are forced to tame the high powers with heavy projectiles. That is fine if you are hunting, you want a heavy projectile. But once again you have to deal with vibration, etc. of the rifle.

        PCPs help eliminate most of these issues, but have issues of their own. You need a pump, scuba tank and/or compressor before you can hurl the first pellet downrange. That is why I have an interest with SSPs. The main limitation they have had to this point is sufficient FPE for longer ranges. Perhaps one day I will be able to aquire a SSP that will give me my 1 MOA at 50 yards. We all like to dream.


        • I have the same dream…

          My other dream is finding a springer that is 1 MOE accurate at 50 yds – that is not hold sensitive AND doesn’t weigh more than 6.5-7 lbs (so that it can be shot off-hand with ease)…

          I’m personally not sure whether I’d rather deal with the fps variation of a unregulated pcp, or the mild recoil of a detuned springer.


    • First we must know the mass of the neutrino. The heaviest, the Tau, is less than 15.5 Million electronVolts (per Wikipedia) equivalent. Now, convert that to grains… Since eV is really a unit of energy we can go directly to another unit of energy: ft-lbs. According to my HP48sx

      15.5MeV => 1.8317E-12 ft-lbs. (or: 0.0000000000018217 ft-lbs).

      And remember, most of that comes from the velocity, which is normally just shy of the speed of light. Given that velocity, and that neutrinos rarely interact with matter, it has no trajectory to worry about — if you can point at the target, you’ll pass through the target (you’ll need a rapid fire system to get enough of them downrange to have one impact a nucleus)



  26. A little off topic but I need some advice about shooting for max accuracy off a bench with big bore pcps. Maybe some low velocity powder burner experiences would be applicable too?
    I just built a “real” permanent outdoor shooting bench that is rock solid and fits a person very well. So what do I need now? BB, in pics of your testing sessions, I have seen sand bags and other “soft” supports, and I see that real snazzy red support that you used in the CB testing series. I know there are levels of “investment” for these things so what would you suggest for the best, and then maybe backing down on the investment till you get to sand bags. Also, how useful/necessary are all the adjustments on the real nice ones? With a gun that has moderate recoil (200-500fpe) how does the support deal with the movement?
    Thanks,
    Lloyd


    • The red rest (MTM Monster?) is perhaps less expensive than bags and does a good job. It isn’t recoiless — so your shoulder isn’t unemployed, but it does hold the rifle steady on target. You should probably just buy one while you research bags and/or recoil-less ultra-rests — the adjustments on it are all you need in most cases to turn in excellent groups; you will have to re-position between shots, in my experience, but only in windage usually. I’ve used the loaner at my range (it is identical to BB’s rest) to shoot many MOA and better groups with my .30-06. I’ve been wanting a Lead Sled, but I can’t really justify it in terms of any real benefit for very occasional use.


      • I just used a Lead Sled last week that belongs to a friend. I wasn’t impressed with it. While it works, it makes your length of pull way too long. Also. 25 lb bags of lead cost about $40.00 each, perhaps more. The sled needs at least four of them. You can do the same thing with sand bags and a pedestal rest and save a lot of coin.

        Mike


    • Lloyd,

      I’m not certain, but I always rest my big bores on sandbags or that MTM rest, and they seem to do well. Maybe I should test the artillery hold?

      B.B.


      • BG and BB,
        Thanks for the advice. I’ve made some sand bags out of old pant legs and they work pretty well, but I need some more and that MTM rest looks like it’s worth the money and a try.
        Using the artillery hold on a bigbore, it seems like the technique would have to be just right, and that there might be a practical fpe limit. I don’t know.
        Lloyd


  27. B.B.

    I think that this caliber/speed stuff must have something with the time pellet spends in the barrel and “jerkforce” of the rifle’s piston. The more speed you try to squeeze out of a rifle – the more jerkforce it has and harder it is to control. I’ve never seen .22 springers firing past 250 m/s – so, maybe _any_ pellet will tumble.
    Guess JW would be a nice platform to test 😉
    And another one – I feel there’s something with pressure. PCP builds up pressure in the barrel rather gently, and springers IMO tend to “kick”. Maybe there’s a certain pressure that simply deforms a pellet beyond controllable flight shape. As .22s seem to be larger and thicker – they must have a higher deformation limit, so they stay unifom at higher operating pressures.

    duskwight


    • duskwight,

      My thoughts, exactly! On Wednesday of this week I will start a lengthy test that compares pellet velocity and accuracy. We will see if we are right.

      B.B.


    • I’ve never seen .22 springers firing past 250 m/s – so, maybe _any_ pellet will tumble.

      250m/s => 820.2fps…

      Well… I do have a single sample recorded of RWS Meisterkugeln 14.0gr doing 810.8fps out of an untuned .22 RWS Diana model 54. Being a single sample there is no information on what spread that pellet would produce, nor if that number is high, low, or average. (20.43 ft-lbs)

      As I recall, that model was advertised for 900fps in the days before “PBA” type pellets came out.


  28. I am certainly a fan of the rocker safety Sheridans. They do seem to shoot the old Sheridan “Ash Can” pellets fairly well. I still have a supply of them, some in the yellow plastic packs and some in the metal round tins. I currently have two of them. One was bought new by me in about 1967. It’s mounted with a factory installed Williams receiver sight. The other was bought from “Gun Broker” three years ago and now has a forward mounted scout scope as well as the factory open sight. If I owned only one airgun (as I did for years) it would be a Sheridan. I used them both this year to rid a friends barn of pigeons.

    Mike


    • Ta-Dah! (LOL) Mike, you just did it. By “it” I mean you just expressed what I read experienced airgunners declaring all the time about Sheridans.

      WAY above in this thread I wrote in a post that the Sheridan Streak “is B.B.’s desert island gun, if I remember correctly, and many times I have read posters here and elsewhere declare that their classic-era Streak is the last air rifle they would ever part with.” And just above you said it, “If I owned only one airgun (as I did for years) it would be a Sheridan.”

      The Sheridan Silver/Blue Streak is the ONLY air rifle I can think of (outside of 10 meter legends such as the FWB 300s, PERHAPS) that so many people say would be the last to go out the door, and I have never, ever read anyone challenge that.

      That tells me there is something to it. All of these experienced airgunners cannot be wrong. Mike, you and all the others just have to be on to something, there are just too many of you and no one who disagrees. What frustrates me is that I have had Benji pumpers, Crosman pumpers,Daisy pumpers, and an excellent-shooting S&W 77a pumper, but I’ve never had a Sheridan. Well, I guess I’ll have to change that someday just to see what the magic is with them!

      Michael


  29. Well, it is rather obvious that there is upper limit for pellet velocity, if one is looking for max. accuracy ?

    I mean, it is know fact that there is certain threshold after (any!) projectile in flight starts to experience non-stability, because increased chaotic airflow around the object. Usually this starts in transonic flight speed, which is roughly 0,8 Mach. That is; 0,8 * 341 m/s = 272,8 m/s.

    So if you are looking for optimal flight speed for example for .22 pellet, do not exceed 272 m/s (891 fps). Of course, this is not a absolute value, but it pretty close… For example, 300 m/s pellet is a lot more unstable than 270 m/s pellet. That is scientific fact.


  30. Oh, one more thing about the speed; just like “real” bullets pellets too have variable ballistic coefficient. So basically aerodynamic drag of pellet varies throught the flight. For example, when .22 JSB Exact flies with speed of 290 m/s it has BC of 0.024, then further in flight, when speed is say, 210 m/s, BC is 0.035 !!!.

    Those are not real BCs, but the ratios are correct. So ie. if you are shooting for 50 meters with .22 JSB maybe it would be best (if possible) try to “tune” the pellet speed so that it is inside best possible speed zone throught the whole flight.


  31. Concur with eSa. Assuming you want to hit targets common in air gun shooting, there is NO reason to shoot above 275 m/s unless the muzzle velocity is really supersonic and the BC is high enough to keep it there until it hits a target (which is what a high velocity firearm does). Impractical, I think, and might bring unwanted laws into the picture (if it bangs like a firearm, then maybe it is a firearm in the eyes of the legislatures).

    At some low velocity the lock time is too long for the shooter, the drop too great, and the aerodynamic stability too low. Given the inaccuracy of low power air pistols, that’s maybe around 100 m/s.

    So there’s a window, one hundred to 275 m/s. If it’s bad at the low end, and at the high end, and better somewhere, mathematically there is an optimum somewhere in the middle.

    ..Pete


  32. BB, All,

    On the subject of Overbore and at the risk of missing my answer because I haven’t read all comments under this topic; I have a Crosman 2240 that needs rebuilding and am considering using a custom valve (like Crooked Barn Boss) and re-barreling to .25cal. Any thoughts?

    I am hoping to get 450 – 500fps. I plan on using a 14″ to 16″ bbl.

    ka


    • KA,

      You are right about the barrel length. But why .25? W#e know that there are no superlative pellets in that caliber, yet, while there are grerat ones in .22. Yes, you do give up some power, but being able to hit seems more important to me.

      However, I understand scratching an itch.

      B.B.


      • BB,
        Thanks and sorry for not noticing your response earlier. The situation is that the targets are rabbits and the energy needs to be ample to insure a humane kill. The distance is 10 – 15 yds with an undesirable overshot zone behind at about 30yds. I did not figure for the lack of variety in quality pellets that the .22 offers, just a slower pellet with more energy at impact that the .25 offers. I was on the track of using a larger diameter pellet with similar weight as .22 to bleed off energy more rapidly. It’s all in my head at this point, as no bbl has been ordered yet, just considering the larger chambering at this point. There’s the possibility that I don’t need the High volume valve but a stock one from Crosman with the .25, or go big on the valve and use lighter .22 pellets. The faster, smaller and lighter pellets are sending alarms off in my head as far as accuracy is concerned. Should I do some experimenting or is there lots of common knowledge I’m missing here?

        ka


        • KA

          No, I think you have given this as much thought as you can. I would say go with your gut at this point. Just remember that a .25 is seldom as accurate as a .22, and that is when the best pedigreed barrels are considered.

          B.B.



  33. RE: Overbore?

    Just found this article which I missed. Here is my 2 cents.

    First pellet ballistics is a complicated subject! There are no doubt internal and external components.

    Let’s assume that we want the smallest group size for a pellet. But this doesn’t definitively constrain the problem. For instance an immediate question(s) is “At what distance?” or “Over what distance range?” Shooting 10 meter targets is only at one range. Shooting squirrels would require a rifle which would have a kill zone over some distance range. So the “best” velocity of a pellet obviously is a function of distance and the power needed at the target too.

    Internal ballistics would include such things as the pressure pulse which propels the pellet. It is not uncommon for a springer to have a pressure pulse which enlarges the skirt of a pellet. Obviously if you change the shape of a pellet you change its BC and aerodynamics. So a pellet shot from a springer at 700 fps is not necessarily the same as a pellet shot at 700 fps with a PCP.

    The other obvious difference between a PCP and a springer is the hold sensitivity. I adjust my magic PCP to shoot at a muzzle velocity of 500 fps or 800 fps and shooting at 20 yards. Not much hold sensitivity and the difference in POI between the two power settings will probably be mostly due to gravity. The springer going between 500 fps and 800 fps is likely to get much more hold sensitive. It also will have much greater harmonic vibrations. For the springer it will be truly hard to predict in which relative direction the higher muzzle velocity pellet will land.

    Jumping to external ballistics more factors need to be considered.

    I am convinced that the BC of a pellet is not a constant between 400 and 900 fps. I don’t have the data to prove it other than to point out the work that has been done on the drag coefficient of spheres. A long time ago I tried to point out the similarities between a diabolo pellet and a spool rocket. I don’t think it takes too much imagination to conceptualize that a spool rocket and a wadcutter pellet are very similar aerodynamically. So all in all you’d like to work in the velocity range for which the overall BC is the greatest. (Think of the highest average BC from muzzle to target.)

    However in the real world, given that I may need a certain minimum velocity downrange, shooting precision may need to be traded off to get the necessary velocity. So if you are shooting at rabbits at 100 yards, you may need to shoot at a greater muzzle velocity just to have the energy necessary for a clean kill downrange.

    This leads us to another factor which at least in theory could be varied, and that is twist rate. No twist is necessary to have static stability for a diabolo pellet, but some spin has been proven to help shooting precision. Obviously you could spin a pellet so fast that it would literally disintegrate. So there is almost certainly some optimal spin rate. Again the spin rate would be depended at what range you wanted to shoot. If you are shooting at 5 feet, spin hardly matters. If you are shooting at 100 yards, it would be easy to overspin the pellets so that the pellet’s nose wouldn’t follow the ballistic path.

    Harry on the yellow proposed the notion that it isn’t if a pellet is overspun, but that the problem is better conceptualized as the question “At what distance downrange is pellet going to be overspun?” Remember that two things are working against a spinning pellet. First the forward velocity decreases much faster than the spin rate. So the stabilizing force of tail drag diminishes faster than the spin forces trying to pull the pellet’s nose off the ballistic path. For the second detrimental effect, imagine a pellet fired perfectly horizontally. The ballistic path drops immediately and at an every increasing rate due to gravity. So distance again is against the pellet.

    The other obvious thing here is the “form factor” for the pellet. So what is optimal velocity and spin won’t be the same for different types of pellets such as round balls, wadcutters, round nose, specialty pellets like the Predator, and bullets.

    So I don’t think that there is any pat answer to the question “What is the optimal velocity for a pellet?” without more constraints on the problem.


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