Pellet velocity versus accuracy test: Part 1

by B.B. Pelletier

Welcome to the test that blog reader Mel inspired last week when he made the following comment about whether pellet guns can be overbore:

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 models 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 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.

That got me thinking about something that’s been banging around in my head for a long time. Pellet accuracy versus velocity. Today, I’ll begin a long test to show if there is such a relationship.

I really wanted to write this as if I were a new airgunner who just bought his first airgun, but then I thought about all the confusion Orson Wells caused with his 1939 radio broadcast, despite continuous disclaimers that it was just a theatrical portrayal. It’s doubtful that my experiments with pellet velocities will cause a panic on the East Coast, but a new reader who finds this series a year from now might become very confused. For that reason, I’ll remain in character.

I’m testing the purchase of a .177 screamer breakbarrel spring rifle to see what kind of accuracy we might expect to get. But instead of any of the possible guns that could be selected, I’ve substituted my Whiscombe JW 75 in its place. So let’s clear the air about all the differences right now.


This JW 75 will serve as a testbed because the power can be changed while leaving all other factors the same.

All the differences
First, the Whiscombe has a premium barrel made by Anschütz. So that will be different.

Next, the rifle has the Harmonic Optimized Tuning System on the barrel. The HOTS allows me to move a weight to “tune” the barrel’s vibrations to the best place for each pellet I use.

Third, the Whiscombe is recoilless. Even though it generates almost 30 foot-pounds in .25 caliber (it has four interchangeable barrels, too), it does not vibrate much more than an FWB 300 match rifle.

Fourth, the rifle is both an underlever and a breakbarrel. The underlever requires three pulls to cock the rifle one time, with a combined force requirement of around 100 lbs. Two powerful mainsprings are pulled back so they oppose each other with a 75mm space between the two piston seals. The barrel also breaks open to load the pellet into the breech.

Fifth, the trigger is in the match-rifle class.

And, finally (I hope!), the rifle has an air transfer port limiter that lets me adjust the power as needed. It’s this final feature that caused me to choose this rifle as my testbed.

So, I’m shooting an air rifle with accuracy potential way beyond that of a $350 mega-blaster. But that won’t matter because of how the test will be conducted.

First, I’ll shoot the rifle at its full power potential. That starts today. Then, I’ll shoot the same pellets I test today for accuracy at 25 yards. I will not adjust the HOTS at any time. It’ll just be wherever it is when I installed the .177 barrel, and there it will remain. That will give us a performance baseline.

Next, I’ll install an air transfer port limiter and test the rifle with the same four pellets shooting through the exact same rifle at a lower power level. That second test will be conducted in the same way — velocity of the four pellets first, followed by their accuracy at 25 yards.

Then, I’ll install a different air transfer port limiter to further reduce the rifle’s power. Another set of tests will follow. By that time, we should know if a final round at the lowest possible velocity would be required or not.

What we’ll get out of this is a view of how velocity affects accuracy, with all other variables remaining the same. That will probably suggest other tests that will further advance our understanding of the accuracy equation.

Let’s start with what I’ll call Phase One — the first test of accuracy and power and test four pellets for power.

Beeman Devastators
I selected the Beeman Devastator pellet for several reasons. At 7.1 grains, it represents the kind of pellet a new shooter would select in the hopes that his rifle will shoot absolutely flat, and he won’t have to worry about ballistics because the pellet never drops. You see the same thing among handloaders who pack dynamite in their cartridges behind finishing-nail bullets in the hopes that they will be shooting a laser. The fact that they’ll really be shooting a chaff gun never dawns on them until they try what they have been envisioning for so long. So, for all those armchair sportsmen out there, I picked this one for you!

The other reason I picked the Devastator is because of the neat design. The pellet looks like it wants to blow up on target. We’ll see about that, won’t we?

In my “Forget the dilithium crystals, Mr. Scott, give her all she’s got” tune, the Whiscombe averages 1,216 f.p.s. with 7.1-grain Devastators. The spread went from a low of 1,205 f.p.s. to a high of 1,233 f.p.s., so the spread is 28 f.p.s. That’s actually pretty stable for a spring rifle shooting at this level. The average muzzle energy is 23.32 foot-pounds, which is pretty hot for a spring-piston rifle in .177 caliber. Okay, we’ll store that velocity away for later, when we test the accuracy of this pellet.

Crosman Premier lites
The second pellet I tested was the Crosman Premier lite. I included them because they’re a classic domed pellet, and I wanted them to be in this test. Why didn’t I test the 10.5-grain Premier heavies? Because they’re more often best in PCPs and not in spring rifles. This was just a judgement call and not necessarily the right thing to do. But that’s the way I went.

Premier 7.9-grain pellets averaged 1,134 f.p.s. in the test rifle. The range went from 1,128 to 1,140, for a 12 f.p.s. spread. This is where the good manners of the Whiscombe show through, because at that velocity a 12 foot-second spread isn’t usually seen in a spring rifle. The average muzzle energy was 22.56 foot-pounds.

Beeman Kodiaks
Beeman Kodiaks weighing 10.20 grains were an obvious choice, given the power expected in this rifle. They averaged 992 f.p.s. and ranged from 979 to 1,001 f.p.s., for a 22 foot-second spread. At the average velocity, they generated 22.29 foot-pounds of muzzle energy. According to my experience and beliefs, that’s still too fast for the best accuracy, but we’ll see.

Eun Jin
The fourth pellet I chose (Buy three — get one free) was the 16.1-grain Eun Jin. I figured that they would be heavy enough to lower the velocity into the accurate zone. And they were! They averaged 726 f.p.s. with a spread from 719 to 732 f.p.s. They averaged 18.85 foot-pounds of energy at the muzzle. We’ll see how well they do on paper in the next test, but I must say this — of all the Eun Jins I’ve ever shot, these fit the breech the best. They slid in like any other pellet.

These four will be the pellets I’ll use throughout this test. We’ll compare them for power and accuracy as I adjust the power of the rifle downward in steps from today’s baseline.

Just looking at the results of today’s test, one thing stands out. The classic spring-piston power relationship popped out exactly as expected. Spring-piston guns are usually the most efficient (the most powerful) when the lightest pellets are used, and that’s exactly the way these four pellets are distributed. That relationship will probably remain the same throughout the test, though the close ones may switch back and forth a little.

I’m going to run the second part of this Phase One test very soon so we can keep the data straight in our minds.

84 thoughts on “Pellet velocity versus accuracy test: Part 1

  1. Good Evening B.B. What an absolute beauty of an airgun. If only they were still made. Well, I most likely couldn’t buy one because they most likely would not be for sale in Canada. Mr. Whiscombe certainly had a dream and he realized it. I think there are a more than a few air gunners out there , who have dreams and ideas ,but don’t know or can’t afford to realize them.
    Titus


    • Titus,

      I don’t shoot my Whiscombe as much as I want to, so this is a great opportunity to get it out and blow the dead bees out of the barrel. It had the .22 barrel installed, so I had to switch to .177 right before the test. Even so, the rifle was very close to on target at the start of accuracy testing, which comes tomorrow.

      Got some surprises coming!

      Well, I’m off to Roanoke this morning,

      B.B.


      • I’m with Titus on this: That’s a beautiful air gun!

        I have passed the word on to people that I know in VA and NC about the show. Good luck there BB, Safe travels too.

        ka




      • pcp4me, the AK74 is basically the AK47 action converted from the original 7.62X39mm caliber to 5.45X39mm to imitate the M16 cartridge. I believe it is still the current Russian service rifle. As to range? 2000 yards? :-) Effective range is kind of a subjective thing. The 5.45 is flatter shooting than the old 7.62 but moves easier in the wind and has less stopping power. Some informal tests I’ve seen say both rounds die at around 300 yards or sooner. They’re both traditional assault rifles in that sense.

        Matt61


      • pcp4me, Matt61

        Some clarification if you don’t mind.
        USSR _never_ had an AK-47 as a standard issue assault rifle :)
        The fact is that there are only 3 AK-47 in existence made by M.Kalashnikov’s team (with 4th being destroyed intentionally during the tests) for the Soviet MOD’s tests.

        Kalashnikov’s assault rifle was produced and issued as AK, _no_ “47″ after letters. It’s just like calling M-16 “M1963″.

        Then it was upgraded to AKM (modernized). Upgrades were: stamped steel receiver instead of the milled one, improved trigger/hammer unit, with added hammer release delay device (slightly lower rate of fire), redesigned buttstock and pistol grip, and the addition of the removable muzzle flip compensator.
        Number “47″ is completely incorrect term, however very resistant. AKM is the type of assault rifle most often (and most incorrectly) called AK-47 in the Western media and by non-specialists.

        AK-74 is 5.45×39 version of AKM and usage of numbers is completly correct. It’s somewhat lighter, much easier to control and more precise due to new muzzle brake and lighter, faster, “flatter” round.

        AK-74M is the newest version of AK – with Warsaw Pact accessory rail on the side, ready-to-install underbarrel grenade launcher mounts, plastic buttstock (folds to the right) and foregrip and somewhat upgraded manufacture and assembly tolerances. Specially selected AK-74Ms fitted with scopes are used as DMRs.

        AK-100′s (101, 103 – full size, 102, 104,105 compact) are export, made to use NATO, 7.62 and 5.45 rounds.

        AK-107/108 are the new systems currently supplied – based on AK-74M, but with balanced automatics (think of RWS Diana-75 system) and made for 5.45 and 7.62 rounds.

        Guess that sums it up, and please, be correct and try to avoid “AK-47″ :)

        duskwight


        • duskwight,
          This is very enlightening. I did not know this and apparently there are a lot of others who don’t, either. Including about everybody in the U.S. Someone here in the U.S. needs to answer why we still believe, to this day, that there are still AK-47s and where did we ever get the idea that there ever was an AK-47 issued to Russian troops and “others”. Probably some spy started that rumor before they broke the 4th AK over his head.

          I have shot an AK-74 and I have commented on it in this blog. I did not like it because of the very narrow plastic stock that hurt like H**l with strong recoil. I believe it was designed to be issued to troops wearing very thick jackets.


          • Chuck

            Yes, winter jacket or body armor (or both in winter :) ). Besides that AK is just like Mosin – one has to hold it tight to the shoulder to avoid bruises. BTW that’s the way to quickly recognize terrs that “dissoluted”, it is taught in Israeli and Russian forces AFAIK – just to check out suspect’s right shoulder, as most of them hold it wrong way and there’s 75% chance of a distinctive mark.

            duskwight


            • Oh, and I forgot – there’s a standard-issue rubber “galosh” for the buttstock, first meant to be used on AK-74 fitted with GP-25/30 grenade launchers, but later used much wider and now it’s a common sight on a smart soldier’s tool of the trade – Army ingenuity, you know it.


          • Probably NATO usage to differentiate models by using the year of adoption, since the “AK” alone merely designates an automatic rifle from the Kalashnikov design bureau.

            Similarly, what the US calls an M16 is the ArmaLite AR-15 (what Colt now calls an AR-15 is a semi-auto only version of the ArmaLite selective fire AR-15; Armalite had financial difficulties and sold the AR-15 and AR-10 designs to Colt in the late 50s). The “AR” is taken from ArmaLite’s name.


            • Wulfraed,

              That must be right. However I believe “AK” and “AKM” are more than enough to distinguish two standard models :)
              I wonder how they call RPK and RPK-74 (support weapon, basically – a longer heavier barrel and heavier receiver version of AK with 45- and 75-round drum magazines).

              duskwight


        • Thank you very much duskwight, I never asked for it but couldn’t be happier with this very complete and easy to understand lesson on AK’s. Everything was clear, to the point and easy to understand.

          J-F


    • Krikman

      First, you’ve got to clarify: what do you call “maximum”? The maximum distance a bullet can fly away with barrel at 45 degrees to horizon or with barrel parallel to the ground? I believe that would be some 3200-3500 m for straight shot. Stray 5,45×39 bullet can be deadly up to 2500 m, that’s what I’ve read some time ago.

      duskwight


    • Didn’t you ask this same question yesterday?

      Unless you define the conditions, we probably can’t give you a proper answer.

      Try: http://www.jbmballistics.com/cgi-bin/jbmdist-5.1.cgi

      You’ll have to dig up the ballistic coefficient, bullet weight, and muzzle velocity as the AK-74 is not an explicit entry (whereas 7.62NATO and 5.56 [m16]) military rounds are in the database; though velocity is not)




      • It is my intention to do such. I am hoping to have a good bit of time to talk to you. I just hope I do not become a pest this weekend. I will do my best to stay out of the way when business shows up. If I do, please do not be afraid to inform me of such. I will understand and not be offended.



    • RR,

      PA had advised me several weeks ago that they will not have a presence at the show this year. Their tech/sales manager, Gene Sorvino, informed me they are too busy to spare the staff! I look at this as a plus because last year, it cost me two new rifles!

      Fred PRoNJ


      • Fred,
        Guess I got off easy last year, I only “had” to buy a scope. I am anticipating more damage to the wallet this year, though.
        Lloyd


        • Yep and I just went to the bank! On the plus side, I am hoping to sell 3 air rifles and one pistol. Wonder what Tom Watts will be selling? See you in two days!

          Fred PRoNJ


  2. B.B.,

    Will be interesting to see how the Devastators group; my R1 scattered them at just over 1000 fps so I would be surprised if they do well at 1200 fps.

    Paul


  3. BB,
    This test is going to require cocking that rifle a lot of times, especially at three strokes per shot. Try cocking with both hands. It really reduces the stress on the elbow and allows you to shoot longer without over stressing your arm. At least that is what I have found. I leaned the hard way one day I shot about 700 shots with my old style BSA Lightning. I messed up my elbow and couldn’t shoot for several weeks. That’s when I started cocking the rifle with two hands. It really helps on the rifles with heavy cocking force.

    David Enoch


  4. BB,

    will see you sometime Friday PM with Tom the Seal. I will inform him not to remind me of how much I spend this time.

    Fred PRoNJ



    • Mike,

      From my experience they do! And I would expect almost any pellet to be accurate in the test gun he is using. After all, you are talking about a gun which would go for around $20000 with all four barrels and the case!

      To me it would have been much closer to reality to choose a gun like the 24″ barreled air force talon or a Sumatra 2500 carbine, both of which are adjustable over a really wide range of velocities. And both of which are with in the reach of many more middle to lower income people. And both have a reputation for good accuracy.

      To me, you are changing the dynamics of the gun MUCH more by using limiters which restrict air flow versus just changing how hard the hammer hits the valve of the AF and Sumatra. And there fore how much air volume is generated.

      With the Whiscombe you are keeping the same high volume of air generated, and limiting how fast it can be delivered to the pellet by restricting the air flow, which is not how the lower powered springer’s do it.

      With the AF and Sumatra guns you are reducing the volume of air delivered which is exactly what a lower powered springer does. To lower power manufacturers reduce the piston stroke, and/or use a smaller diameter piston, and/or reduce the spring power, all of which act to reduce the amount of air available and therefore the velocity.

      The Whiscombe is a hand made, one of a kind gun which is carefully engineered and carefully fitted to exact tolerances. It no where near resembles a modern assembly line produced gun of any type.

      So, will these results be meaningful to the majority of us who use assembly line produced guns? Who knows?


      • PCP,
        You make some good points, but let me offer a few other thoughts.

        BBs intent (I think) is to try and compare the accuracy you might get using the same pellets in at least 3 different types of SPRING guns that a new airgunner might buy. A magnum springer, a medium powered springer and a docile plinker. We all agree that PCPs are easier to shoot accurately than springers, but a new airgunner is probably not going to get a PCP as his first gun. So if you tried shooting the pellets in a PCP set at different power levels, I think would be giving the pellets a good test for their accuracy capability, but does that really transfer to springers? Maybe somewhat, but it is the spring/barrel vibration that is the major detractor to accuracy in springers. So, although the test isn’t perfect (and I don’t think a perfect test can be designed) at least all of the shots will be going through the same platform with some commonality of spring dynamics. Who knows, BB may have to shoot these at 40 or 50 yards at some of the velocities to make a real determination of accuracy.

        Now here is something that might happen if the tests were performed in a PCP vs a springer. In a PCP, the accuracy of a particular pellet might stay fairly constant, no matter what the velocity, or might degrade predictably at higher velocities. But in a springer, there might be a sweet spot in the velocity were a particular pellet behaves nicely, but outside that range, it all falls apart.

        So after all that, given the goal of the testing, I think the choice of gun is OK.
        Just my 2 cents.
        Lloyd


        • Lloyd,

          You said, “But in a springer, there might be a sweet spot in the velocity were a particular pellet behaves nicely, but outside that range, it all falls apart.”

          I think this is exactly what BB is trying to define. I believe he is trying to take the actual rifle out of the equation and just concentrate on finding out what velocity alone does to the accuracy of a pellet.

          BB’s nerves won’t be coming into play because we’ve already seen how accurate he is with his HW55 and others.


          • Chuck,
            I really am curious to see how this pans out. I’ve had certain assumptions in my mind for a long time that I’ll probably have to toss in the trash can.
            Lloyd


            • Lloyd,
              I’m with you. I think BB is going to prove what we already think will happen and then in his usual manner he’ll throw in a couple surprises and then we’ll all have to go buy more pellets to see if we can duplicate it ourselves.


        • Lloyd,

          I fully realize that a pcp is much easier to shoot accurately than a springer. I have both. That is a valid point in saying that a pcp might not give a valid test.

          But that is EXACTLY my point about the Whiscombe! It is recoiless! And also in essence every bit the equal of a customized 10M target rifle. Also the Whiscombe uses a totally different principle to lower the velocity that what is used in spring rifles. So I have a valid point saying that the Whiscombe results might not be valid.

          Which brings us to another point. There may be no valid way to discover what we want to discover here! Only way I could figure is to replace the springs in a super magnum rifle with weaker springs to give the velocities we want, but that just may not be possible.

          From my limited experience with pcp rifles, velocity does affect accuracy, but only the velocity in a certain “sweet spot” range gave more accuracy. Go over or under the top and bottom of the sweet spot range and accuracy dropped off!

          I would assume that might apply to spring guns also, but who knows? Does a spring gun shoot more accurately at lower velocities because of the reduced speed, or is it the reduced recoil? Or perhaps some combination of the two? Who knows? And I for one cannot think of any valid way to do that testing!

          We can however discover if a pellet in a pcp gun has a certain velocity range it is more accurate! And I suspect the answer to that is a resounding yes! But those results would be valid for that pellet in that gun. We would then have to test it in maybe 10 – 30 different models of pcp rifles to determine if it is statistically valid for all pcp guns. And then we would have to test multiple pellets in each gun to determine if that also applies to all pellets in all pcp rifles. After all that we could only say with about a 95% certainty statistically if we use 30 different guns or 30 different pellets.

          So testing 4 pellets in one rifle which is not even close to being equivalent to the average spring gun will only tell us if there is such a relationship exists for that gun and those pellets.

          And BB, I am not trying to be hard on you or criticize you in any way. You are a great guy, you have more knowledge of air guns than I, and you do a fantastic job with this blog.

          I am merely stating the way I see things in this instance after careful consideration.


          • pcp4me.
            I think BB is going to prove whether that “sweet spot” exists and, if it exists for that one rifle, then I believe there will be one for all rifles. Maybe in a different place – but it’ll be there.


          • pcp,
            I think we are saying pretty much the same thing, that no matter what type of “velocity adjustable” airgun you test the pellets in, the results are only 100% valid for that set-up. Still, the tests WILL show how the pellets behave with that set-up. Maybe PCPs would show a different trend. I don’t know.
            But I think I see how this is going though. BB left for Roanoke this AM, knowing that he dropped a a stinky chunk in the punch bowl. His plan was probably to let us have a spirited discussion to sort it out while he is away. LOL
            Just a thought.
            Lloyd


    • It was actually my impression from the blog that a good way to make velocity subsonic in a powerful gun is to use a heavier pellet. Can’t deny the physics here. To maintain the same muzzle energy with a more massive pellet, the velocity must go down.

      Matt61


      • Matt61,FWIW,my “Whizzer”,a JW80 shoots the 10.1 gr CP heavies at around 1000fps almost exactly.
        No puns intended.I had hopes they would have been slower…..but I have shot flies on the target at 25
        so accuracy is still pretty darn good.My AF guns have incidentally bagged the most insects.IIRC,Tom shot a spider once at 50yds! Ever see the guys compete in the Powderburners “Flyshoot”?? There have been some insane groups shot at 600yds by some of them.



  5. BB,

    Any bets on velocity versus accuracy before you start the accuracy tests?

    I am betting no pellets will be accurate at over 1100 fps. And probably none over the 1000 fps range either.

    IF any are to be accurate at that fps it would be the CPL. The Kodiaks start real close to 1000 fps and I would bet they would be more accurate at a lower velocity.

    The Eun Jins OUGHT to be accurate until you lower the velocity too low to stabilize them. I must say I am absolutely amazed at how low their velocity is in your gun. In my Sumatra 2500 carbine in .177 set with power wide open the Rws Hobbies get 1250 – 1300 fps and the Eun Jins still average 950 – 985 fps!

    In that same gun I can lower the EJ’s down to 400 fps and they are not as accurate.

    I am VERY surprised you did not use the RWS Hobbies as they are a WAY more accurate pellet than the devastators! For me the devastators never shot accurately in any gun at any velocity. And you could readily see why as they varied wildly in size, shape, and skirt regularity. Oops, sorry wrong beastie. I used the Crosman devastators which look to be the same beastie, but on the PA site the Beemans look way more uniform than the Crosmans I have. So I will be interested in just how accurate they will shoot at different velocities.

    I still wish you had chosen the hobbies, as in some of my guns they give very close to the same accuracy as premier pellets such as the R10s and the Finale match do. Could you possibly throw the hobbies in as a fifth pellet? I believe a new shooter would choose them over the Beeman devastators any way! They are $6.99/500 versus $11.95/300 of the Beemans!



    • Pete,

      Because in that gun you would expect competition grade pellets to stack all pellets in one single hole at most any usable velocity levels and it might be hard to measure any statistically meaningful differences?

      But here are my thoughts on the subject.

      All competition guns limit velocity into basically the 450 – 600 or 650 fps range. I am assuming the producers of said guns know something and there is a really GOOD reason to limit the velocities to that range! I am then assuming further that the reason is that they discovered the lower velocities to be more accurate. After all, aren’t competition guns all about accuracy?

      Also we know that going over the speed of sound creates a shock wave which buffets the pellet and interferes with accuracy.

      I also found out with my Disco when I installed a power adjuster that set at five turns in from initial contact with the spring guide I got maximum velocity from it using 14.3 gr chps. And also that was so close to coil bind as to be scary. I also found that by setting it at 4.5 turns in from first contact I lost about 60 fps and gained a measurable difference in accuracy even at 25′. Dropping it in 1/2 turn increments did nothing to affect accuracy till I got below 800 fps at which time accuracy started falling off rapidly. So with this gun only and with 14.3 gr chps only there seems to be a “sweet spot” above 800 fps and below 900 fps.

      I still need to do additional testing at longer ranges and also with different pellets, but the 14.3 gr chp gives excellent accuracy in that power range and even at longer ranges set to about 880 fps I get great longer range accuracy and terminal performance on tree rats is perfect to date.

      With my attitude being “If it works why mess with it?”, it may be quite some time before I generate any additional data!


    • I would imagine the sole reason for excluding them is the range will likely be 25yds.This is such an ambitious undertaking……and I’m really excited to see the results!
      Perhaps a 10m followup test to this that includes a precision pellet or three would make a nice contrast.
      I am still amazed at the ambition BB must posess,given the need to optimize the Whizzer for each pellet
      AND velocity.I did not find it an easy task to get mine set up,and I don’t have transfer port limiters,either.
      Thankfully I don’t have a .20cal barrel (yet).I won’t even reveal how much a .25 and .177 barrel cost me.
      Suffice it to say,I could have bought a couple Marauders instead!


      • Didn’t he state he would NOT be adjusting the barrel weight to optimize per pellet — in order to minimize influences that aren’t available on common spring models.

        Though I will agree that a port limiter, while having an effect of final speed, may not reproduce the effect that one would obtain by using a different spring. Changing springs to something weaker would tend to reduce peak pressure, but may not change the pressure curve that much. A port limiter, OTOH, is probably going to stretch out the pressure curve — so a heavy, slow accelerating, pellet in the changed spring experiment would still have the peak pressure hit before it gets far down the barrel if not before it even moves, possibly deforming the skirt (that is, pressure starts at maximum and decreases throughout). The limiter though may keep the pressure low-enough to avoid skirt damage, but support constant acceleration throughout the firing cycle (no pressure drop once the pellet starts moving).

        With the tightest limiter in place, we may discover that heavy pellets work best, as the pressure curve is closer to a PCP…


        • In his second statement above,about the barrel…….the way I read it he will be tuning for each pellet.Perhaps just to dial it in,and not for each individual velocity level? BB,can you clarify please?
          Oh,and safe travel everybody! You lucky devils……


          • Quoting from the blog itself (emphasis is mine)

            First, I’ll shoot the rifle at its full power potential. That starts today. Then, I’ll shoot the same pellets I test today for accuracy at 25 yards. I will not adjust the HOTS at any time. It’ll just be wherever it is when I installed the .177 barrel, and there it will remain. That will give us a performance baseline.



            • I apologize to all for my lack of aptitude.I only looked at one spot in today’s blog.This all makes more sense now.Reading IS fundamental!


  6. Okay…all you guys and this accuracy talk has finally gotten to me.
    Yesterday I purchased a set of digital scales.
    The winters project is to sort the 5000+ pellets I have on hand.
    This past weekend I finally did it…I had a 20 shot group measured about .5″ (30m with my Slavia)…except for about 3 ‘flyers’ which opened the group upto 1.5″.
    I’m using a sniper databook…carefully logging each shot and the 3 flyers should have (IMO) done into the same hole as the other.
    I figure now it’s time to start sweating the detail…and weighing the pellets seems to be the place to strart.
    But I look at the pile (15 opened tins) and am not looking forward to it ;-)


    • CSD

      What we need is a magical machine that weighs and sorts pellets as quickly and accurately as those automated dollar bill counters at the bank. Wouldn’t that be cool? Lloyd? Are you out there?


      • Slinging Lead,

        That would be wonderful. I recently had to sort 200 pellets by weight as they had become intermixed. Sorting was by weight as the pellets looked the same, but there were 100 – 6.8 gr nominal weight and 100 – 8.2 gr nominal weight.

        Seemed to take forever to sort them into 2 piles of 100 each.

        It was a real eye opener to say the least! The “6.8 grainers” went from 6.4 grains to 7.1 grains each and the “8.2 grainers” did a little better at 7.9 – 8.4 grains each. But most of them weighed 8.1 – 8.2 grains each where the lighter pellets had a lot of pellets falling into the 6.4 – 6.5 grain weight with the most common being 6.7 – 6.8 grains. And there were still way too many falling into the 7.0 and 7.1 grain range with very very few weighing 6.9 grains or 6.6 grains.

        With so wide a possible dispersion in grain weight is it any wonder there are fliers?

        I would imagine the “premium” pellets would show a much tighter spread. At least I would hope so!

        Some of the higher priced ones are advertised to be “hand sorted” and cost a bundle, so I would hope those all have the same weight and head and skirt diameter are uniform.

        Talk about a boring job. Sorting pellets by hand all day long 8 hours a day 5 days a week!


        • I can only imagine how much a “presorted” tin would cost.I was astonished at the range of weights in a tin the only time I ever weight sorted them.It was like sorting mixed nuts…….only no finger licking!
          It is a miracle unsorted pellets hit anything near the target at 50 yds.I need to do another tin now to further fine tune the HOTS system.Plinking sure can be complicated stuff.No wonder BBs are still around.


          • Here’s an example of how expensive.
            On Pyramyd’s site RWS R-10 are $12/500.
            The ‘Premium’ R-10 (supposedly sorted by weight) are $40/500. So nearly 3.5x the cost…or $28 more.
            A friend of mine claims he can sort a tin in about 20 minutes…so I guess it is definitly cost effective to sort your own…unless you are making in excess of $80/hr ;-)


    • On his last visit to my place, my Dad developed this mania for sorting my large pile of loose change into appropriate paper packages for deposit at my bank.

      Matt61



  7. Safe travels B.B. This is quite the rifle, and I would say that it is uniquely suited to testing the variables of this experiment like a moving airgun laboratory. Even so, the generalization of the results will have to run up against the variability of different guns. As we found out with the neutrino experiment, it’s hard to know just what is going on out there. But the results will be interesting and valuable no doubt.

    Victor, I forgot to respond to your point about ring height. Perhaps my good offices with the Savage rifles are not done yet! I had the same problem myself. My Leapers scope with its 50mm objective did not fit the first set of low rings. The high rings that I got raised my head too far off the stock. The solution? An adjustable strap-on cheekrest from Blackhawk for $25. It fastens on the stock with Velcro and has three removable inserts to get the right height. Two is perfect for me. With the pad, you can retain high rings that will fit any scope, support your cheek weld properly and drop the butt down into the shoulder. Actually, I think any hard stock has limitations on how it will fit the shooter unless it is heavily customized. The $25 Blackhawk cheek pad feels just as good as the adjustable butt on the $2500 Anschutz rifle. Oh, and the cheek rest looks very cool and tactical as well. :-)

    On the subject of concealed carry, others know much more about this than I do. All I will say is that if I ever were to start carrying, I like the idea of multiple backup guns. I got this idea from a movie with Tommy Lee Jones and Harrison Ford that I think is called The Witness. Ford somehow disarms Jones (who is pursuing him) of his pistol when lo and behold, Jones opens a sort of belly band and pulls out another one. I could also see some sort of small concealable revolver in an ankle holster; Smith and Wesson has a whole line of them. But this would probably be more appropriate for a professional operator than a citizen defending him or herself.

    Edith, I see that Smith and Wesson makes a “Professional” series 1911 that has a three inch barrel and is designed for concealed carry. Shooting through your purse is an interesting idea. I read an anecdote from the Korean War where a G.I. woke up in his sleeping bag to find a Chinese soldier standing over him, ready to thrust with a bayonet. The G.I. emptied his 1911 from inside the sleeping bag and it worked fine.

    On the subject of self-defense, what is the story on “brandishing”? I know that B.B. said that brandishing can get your carry license revoked. But I have been reading self-defense stories in gun magazines as a new avocation and more often than not, the sight of the leveled gun causes the assailant to run away. This would seem to be more desirable than actually shooting someone, so from a certain point of view, brandishing is the goal. I know that you are never supposed to bring a gun into play without being willing to use it, but that doesn’t mean that you always shoot when you pull the gun either. Anyway, I think that this is something to sort out before carrying a weapon.

    To follow up the story of Phoenix Jones, the Seattle superhero arrested for pepper spraying people. The outcome was far far more humiliating than I had supposed. Rather than getting laughed at in his outfit, he had a woman swatting him with her handbag!

    On the subject of reality shows, it is timely to note that with all that we’ve said in criticism, that I’ve fallen completely under the spell of one on YouTube. It has to do with Repo men down South who are always trying to repossess the property of guys who seem to be bodybuilders. Big cars, huge good old boys brawling away… I am just entranced. It does make me wonder, though, about the legal status of the Repo men. More often than not the issue seems to turn on a physical fight. And what happens if some of the people getting repossessed pull a gun? If they act as irresponsibly as they do with their big muscles, there will be blood.

    PeteZ, Lisa Randall’s comment was that we are not physiologically designed to perceive the additional dimensions besides our three but “we can see it in the mathematics without too much trouble”…. Maybe not for her.

    BG_Farmer, I was just kidding around. :-) The fact is that I’m still looking forward to my first loading that doesn’t jam my rifle.

    Matt61


    • Matt61,
      The $25 Blackhawk cheek pad sounds like a great product. I had envisioned that such a product should exist. But the issue was not just the height of the scope, but also eye-relief. Lowering the scope causes the eyes to naturally move up closer without neck-strain. In the case of this Savage rifle, I don’t think we want to adjust the cheek. We want a more natural combination. Thanks for the suggestion. This Blackhawk cheek pad may come in handy for other situations.
      Victor


  8. In my opinion, it doesn’t matter what rifle or pellet is used for this test because the objective of this test is only to see how speed affects accuracy. If a pellet shot from this Whiscombe groups larger at higher speeds it’s a good bet it will group larger with any other rifle at those higher speeds – objective achieved. The only other proof observed will be which brands of pellets will group larger than the others at those higher speeds. I just hope we will get large enough group size variations to produce meaningful measurements.


    • The sad thing about any significant variations will be that we will never know how much of those are due to crossing and recrossing the sound barrier, as well as the state of B.B.’s nerves at the time. We could eliminate the first by sending B.B. up to the ISS. Shall we start a collection?
      -AlanL


      • AlanL,

        No need to worry about B.B.’s nerves. As someone who has observed him first hand, I’d say he’s got a LOT of nerve :-)

        Edith


      • Alan,
        Why would it matter if we don’t know how many times it crosses the sound barrier, if at all? All we need to know is that if the speed exceeds 1,111fps, for instance, the pellet becomes inaccurate. So, now we know we shouldn’t shoot that pellet that fast. Isn’t that enough info right there?


        • Chuck,
          Hmmm… I don’t think I said it mattered how many times it crossed, only that crossing and recrossing would affect accuracy. But you are right– it’s irrelevant if above a certain speed a pellet shot badly. Nevertheless, performance might improve again at even higher velocities for a pellet that had shown a worsening at some lower velocity. With that said, would shooting in a vacuum render velocity irrelevant to accuracy? I’ve always wondered about that.

          B.B.:
          Have you considered recording your velocities at the target as well as near the muzzle? It would be fascinating to know how much the velocity declined for each type of pellet from muzzle to target!
          -AlanL


          • Alan,
            My thinking there was the pellet could cross at most twice: once while accelerating and again on deceleration. It’s possible that it would cross only once because it would hit the target before having enough time to decelerate enough to cross back down.

            According to Wulfraed, however, the pellet is already going the speed of sound before it leaves the barrel so there would be no effect during acceleration, therefore, there is only one time for the pellet to cross the sound barrier and that’d be during deceleration unless it hits the target before then, in which case, there is no effect at all. This conforms to your opinion about improved accuracy at a higher velocity but only if the pellet hits the target before dropping back down through the
            s-barrier.

            I would be inclined to think shooting in a vacuum would render velocity irrelevent since it the effect of air turbulence/pressure causing all the problems.


          • AlanL,

            Not until I know where these pellets are going! Sam Fadala blew up three sets of Oehler skyscreens b y downrange testing black powder bound ball shooters.

            And Oehler may not be able to replace my screens! I already have duct tape on them.

            B.N.


      • Unless you’ve got a very weird weather pattern, the free-flight pellet will only cross the sound barrier ONCE. Remember, maximum velocity will be reached inside the barrel, and the pellet will only be slowing down after it exits the muzzle. The only multiple crossing could occur is if you have “waves” of density changes in the air such that the pellet velocity is above sonic in some densities but below sonic in others.



          • Would the shape of an object even have an effect in a vacuum? Let’s see, the only forces left there are gravity and any gyrosopic influence caused by the rifling. Did I leave anything else out? I suspect I probably did otherwise it sounds too simple and we wouldn’t need computers to control space craft.


          • In total vacuum, shape shouldn’t matter — a pound of lead and a pound of feathers will fall at the same rate.

            A sphere, however, is the easiest shape to machine for NASA’s high speed impact tests (which basically use a long tube with a vacuum to “suck” the projectile down its length where it bursts out the end and into the impact medium).

            Of course, there are influences from solar radiation, gravity variations, electromagnetic forces…



              • Presuming both vacuum AND no gravitational torquing — I wouldn’t expect spin to have any effect.

                If we do have gravitational torquing (gravity is tugging on one part of the pellet more than another) I’d expect it to act as a toy gyroscope would when you nudge it with a finger. Similar with an imbalanced weight distribution (“out of balance”). Both should result in yawing of the pellet, but with no air drag, no Bernoulli effects to cause it to diverge from straight line trajectory.


    • Chuck,

      You make a LOT of invalid assumptions!

      ALL this test will prove is what these 4 pellets will do in this particular gun. This test will NOT develop enough data to extend the results to any other spring powered rifle as this gun is recoiless and most others are not. And this gun uses limiters to change velocity. I don’t know of any other spring gun that does, though there may be one or two. But I would bet if there are any, they are NOT readily available as the Whiscombe is not readily available. To get enough data, you need a much larger sampling of spring guns where the velocity could be varied.

      Perhaps you could have a machinist bore out the transfer ports on magnum spring guns and make a set of limiters which could vary the power. With a large enough sampling of high powered spring guns modified in this way you could develop some meaningful data. But it would only apply to magnum springers modified this way!

      Now you could develop statistically meaningful data on pcps as there are many available with adjustable power. But again you could not apply that data to guns with any other type of power plant as they simply are not the same animal!

      My feeling is WHY even do this with a spring gun? After all, how many spring guns are manufactured which allow you to vary the velocity? So what’s the purpose? Even if it WERE valid data and COULD be applied to ALL spring guns, there are exactly ONE spring gun I know of where you can vary the velocity and that is the Whiscombe!

      Basically this particular test will be similar to taking a coin, flipping it 10 times and it comes up heads 7 of the 10 times, so you say that every coin flipped 10 times will come up heads 7 of 10 times. Not enough data to make that assumption! Not the best analogy, but you get my drift.

      So why not use several pcps (7 or more) with adjustable power and a variety (7 or more) of pellets? There are a multitude of pcp rifles with adjustable power widely available. Sure if done right the test would take MUCH longer.

      Granted most beginners would not buy a pcp, but then again most (if not all) of beginners are not going to buy a Whiscombe either. At least with pcps you could get enough meaningful data to apply to adjustable power pcp guns!


      • My take on it is that the Whiscombe was chosen to reduce the degrees of freedom in the experiment. Recoilless to reduce hold sensitivity; spring piston to obtain (at least on wide-open) a typical spring gun’s pressure curve (I’m still ambivalent as to how well a limiter in the port will reproduce the pressure curve of a gun with either weaker springs or smaller chamber displacement). Thereby the only targeted degrees of freedom are pellet weight and pellet velocity. Four pellets X four velocities; experiment results ideally illustrate the free-air ballistics and not contributions from the gun itself.

        The only way to extend this, scientifically, would be to build a custom rig with a barrel essentially welded to a steel slab (or maybe just end-supported under tension) with the chamber end threaded to accept custom made piston cylinders. Make up a set of pistons in various diameters, stroke length, and spring strengths. Clamp the rig to a concrete block floated on vibration dampers. Heck, to reduce the effects of the piston stroke, maybe the cylinders should thread to a short length of high pressure flex hose, with the cylinders mounted to a separate concrete block. This way you remove all human elements too (“was I dead center with the crosshairs when the trigger released?”).


  9. Everyone,

    You guys have it right. I’m using the Whiscombe to represent three different guns. I was going to role-play and say that I de-tuned the gun each time, but as low as that rifle can go is not possible with a tun unless you use bubble gum on the spring.

    B.B.


    • BB,

      Love ya man! But this won’t represent three different guns. It will only represent one gun with three different sets of limiters. I “get” what you are TRYING to do, but it don’t fly in the real world!

      As I have stated correctly before, the three different guns would all have different piston stroke lengths and/or different piston diameters and/or different power springs. So I know of no practical way to produce valid results in a spring gun.

      Also, the Whiscombe is the only springer I know of that the power can be varied. In the real world you need three totally different spring guns for three different powers.

      I know what your are trying to accomplish man. But sadly the data you will get will only apply to this gun under these test conditions. You and I both know you can’t take this data and apply it to three totally different guns where each one individually has a single power level and collectively all three power levels are different as all three guns are totally different. Statistically that just is not valid!

      And people can take any data they want and make “assumptions” but that don’t make it true! I believe that is called “wishful thinking”

      That sums up all the 2 cents worth of thinking I have on this subject so let’s move on.


      • pcp4me,

        Don’t obsess over this — please! I know this rifle is unique. I tried to address that in the report.

        What is does do, as Lloyd has pointed out, is point out the comparative accuracy of four pellets at three different velocities — FOR THIS RIFLE. Sure those accuracies will be different in any other rifle, but the trends might be the same. That’s all I’m after.

        I’m not looking for the Grand Unification Theory in this one test – and by one test I mean all the testing I do with this rifle in this series. But this test will point out other tests that possibly should be conducted, as well.

        That’s all. :)

        B.B.


  10. I have another idea. Why don’t we let BB report his testing and then let his results decide if it’s worth continuing or if it’s time to move on. I think we’re overthinking the issue.


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