They have the wrong twist rate!: Part 1

by Tom Gaylord
Writing as B.B. Pelletier

This report covers:

  • Then came big bores
  • What am I talking about?
  • Bullets don’t work like pellets
  • Bullet length
  • Why bullet diameters matter
  • Hard cast lead bullets
  • Putting all of this together
  • Last story

Before we begin I have some startling news from Umarex USA. Sales manager, Justin Biddle contacted me and told me the new Hammer big bore is regulated.! I certainly did not know that, because this is huge news. It means that those three shots it gets on a fill can all be at the same power level. I have adjusted the SHOT Show report (Part 6) to reflect this new information. And by a strange coincidence, this dovetails nicely with today’s report.

For many years I have written about black powder firearms in this blog, and I have included things like rifling twist rates in those articles. And for years people have written me comments that they appreciate a look at something different, but they would never consider shooting black powder arms or even modern firearms, themselves.

Then came big bores

A few years ago, big bore airguns began rising in popularity. First it was the exotic guns (I call them boutique guns, though Quackenbush, alone, has reached low-rate production levels) from makers like Dennis Quackenbush that a few lucky shooters were fortunate enough to acquire. Before long, though, the Koreans began making big bores airguns in volumes large enough that U.S. shooters were able to buy big bore airguns at will.

Dennis makes his rifles for shooters who understand the ballistics and needs of a big bore airgun. They either come from a background of black powder or they embraced it quickly after acquiring their airguns.

In sharp contrast, the Korean big bore makers fumbled the ball more than once — not understanding the subtleties of the variations in actual bore diameter among “common” calibers like .45 (there is .451/.452 for the .45 ACP cartridge, .454 for the modern .45 Colt caliber, .457 for the antique .45 Colt caliber — same cartridge, but the bore diameter changed in the early part of the 20th century, and .457/.458/.459 for the .45 rifle cartridges like the .45-70 and others. Each foreign manufacturer produced rifles with barrels having whatever bore diameter they wanted, and for a long while there was chaos in the world of big bore airgun.

They followed that with a slew of smaller rifles they insisted were 9mm, which is a bore diameter of .355/.356. I suppose they thought that the 9mm cartridge is so ubiquitous that shooters would be able to get bullets to shoot anywhere. That is true, but 9mm handgun cartridges almost always use jacketed bullets that don’t work in air rifles. Air rifles like soft lead bullets, and there are very few of those in 9mm. But there are a host of them in .357. Heck — that’s only one-thousandth of an inch larger, the reasoning probably went. Those should work in these guns, too, shouldn’t they?

What am I talking about?

You probably think I am ranting about bore diameters today, but I’m not. I’m just getting warmed up to talk about twist rates. However, until you understand the dynamics of everything involved, none of this bullet stuff will make sense. That is why I wrote all those articles about black powder firearms in an airgun blog.

Bullets don’t work like pellets

I am a real fuddy-duddy about calling a bullet a bullet! Bullets are not diabolo pellets, and calling them that on the package doesn’t change their dynamics. Bullets have to be stabilized by spin, because they don’t have the same high drag factors that diabolo pellets have to keep them pointed straight ahead while in flight.

Spin is induced by rifling, which are lands or ridges cut in a spiral inside the bore. These ridges or lands cut into the sides of the bullet (it’s called engraving) and make it turn to follow them. As the bullet travels down the barrel it rotates according to the rate at which the lands turn. And here is the first truth you need to grasp. Whether the barrel is 2 inches long or twenty inches long, if the twist rate is the same and the velocity remains identical, the bullet will always spin at the same rate. That’s right — a 2-inch barrel with a 1:10” twist spins a bullet just as fast as a 20-inch barrel with the same twist — as long as the bullet is driven through both barrels at the same velocity. Longer barrels don’t spin the bullet more.

And, here is the second truth you need to learn — regardless of the twist rate, the faster the bullet travels through a barrel, the faster it spins. It is the bullet’s velocity that determines how fast it spins, not the barrel’s twist rate. That said, a faster twist barrel will spin a bullet faster at a given velocity.

So, if the barrel has a twist rate of one turn for every 12 inches of travel (written as 1:12”) and the bullet is shot at 1,000 f.p.s. it exits the muzzle spinning 1,000 times per second. If it is shot through the same bore at 2000 f.p.s. it exits the muzzle spinning 2,000 times per second. The length of the barrel has no bearing on this.

The third truth about bullet spin is it does not slow down very fast after leaving the barrel. When a bullet finally falls to earth after hundreds or even thousands of yards of travel, it is still spinning nearly as fast as when it exited the muzzle.

Bullet length

The longer the bullet (in relation to its diameter), the faster it needs to spin to stabilize. Those who reload understand this very well, because their favorite bullets are only accurate within a narrow band of muzzle velocities.

The longer a lead bullet of a given diameter is, the heavier it is and the slower a big bore air rifle will drive it. Less muzzle velocity equals less spin, as we have learned. But longer bullets need more spin to stabilize. We have a dilemma. Firearm shooters resolve this by using gun powders with different burning rates that generate greater pressures for more push. Black powder shooters can only load more powder and shoot through longer barrels, both of which soon reach the point of diminishing returns. Big bore air rifle shooters can only use the longest barrels they can get, and sometimes they can increase the reservoir pressure, though that isn’t as straightforward as it sounds. In other words, big bore airguners need to shoot the right bullets to get the best performance. They don’t have the flexibility of bullet selection that a firearm shooter has.

Why bullet diameters matter

And this is where the bullet diameter matters. Let’s consider a .45 caliber bullet, for example. A .45 ACP bullet measures .451/.452-inches in diameter and it is very short. The weight range for this bullet in lead stretches from a low of around 160 grains to a high around 230 grains. The lighter bullet is shorter, so it needs to spin less fast to stabilize. That means you can shoot it slower from a gun with a given twist rate barrel, or you can shoot it through a barrel whose twist rate is slower than a heavier bullet would require.

A given big bore will drive this pistol bullet (.45 ACP) at a certain velocity. The shooter needs to find the weight and length bullet that stabilizes the best and is also the most accurate in his rifle. When he does — that’s it!!! You can’t make a 200 foot-pound Korean big bore shoot a 500-grain lead slug, even if you could find one in .451/.452, which you never will.

Some big bores have a limited range of power adjustment or they have two fixed power levels. Even with that flexibility they will still only shoot best with a narrow range of soft lead bullets (both diameter and length). As much as you may want to shoot something different, it “ain’t a’ gonna” happen. Shooters who are familiar with black powder arms understand this, because that’s been their experience. But a lot of airgunners are getting into big bores today and have missed all of this discussion about bullets, so they get surprised. I consider it my job to inform them, but I only reach the ones who will read and understand.

Hard cast lead bullets

As if the aforementioned discussion wasn’t confusing enough, there is another fly in the ointment — hard cast lead bullets. They exist for one purpose, and one purpose only — to allow heavy charges of powder to be used with lead bullets. In other words, to drive lead bullets faster than they are normally designed to be driven. Hard cast lead bullets are hardened through alloying antimony with oure lead that makes the lead much more resistant to deformation. Unfortunately, besides keeping the bullet from “skidding” in the rifling under extreme pressures, this process doesn’t add anything else that is desirable. It causes massive lead deposits to be left in the bore that soft lead bullets will not leave unless they are driven way too fast — far faster than any big bore airgun can drive them.

But many bullets on the market are hard cast. They look better, deform less through handling, fill out the mold better and they are much easier and quicker to cast. So bullet makers tend to make more of them and shooters tend to buy and shoot them without realizing what they are doing. They end up with lower velocities, bullets that don’t deform well in game (sometimes they break apart without mushrooming) and barrels that lead up with just 40-50 bullets shot through them instead of the hundreds of shots they could get with soft lead.

Putting all of this together

If you intend getting into big bore airguns, or if you are already there and things aren’t going as well as you had hoped, your bullets may be the reason. Nobody in their right mind would buy a Corvette automobile to tow a horse trailer, but big bore airgunners are doing the equivalent when they select bullets that are not compatible with their airguns.

If all of this discussion sounds real deep, consider this. If you and I were to have a conversation for one hour on the same subject I would probably tell you five times as much about bullets and still just scratch the surface. Don’t be that shooter who buys a big bore air rifle on a whim and then whines because it isn’t what you thought it should be. Learn about this part of the hobby and enjoy yourself! That is why I am making this report a Part 1.

 

Today’s title is taken from a lot of discussions on the airgun forums by shooters who have bought big bores but never invested the time to discover for what purpose they were designed. They are too ready to condem before understanding.

Last story

I remember talking to a guy years ago who owned a vintage Remington Rolling Block rifle in .43 Spanish caliber. That is the military designation for the .44-77 civilian caliber cartridge (.44 caliber and 77 grains of black powder in the cartridge0>. The guy went out and bought some reloads, then complained to me that his rifle couldn’t group 5 shots in less than two feet at 100 yards.

A couple years later I acquired a vintage Argentine rolling block in the same caliber, but I researched the gun, and the caliber. I found out what the proper loads were. I bought a bullet mold and cast bullets of the correct size and lead softness for it. Eventually I shot 5-shot groups of perhaps 5 inches at the same 100 yards with my rifle. My .43 Spanish rifle had a bore diameter of .4385-inches and favored a .439 soft lead bullet weighing 375 grains and traveling 1300 f.p.s. or more.

Isn’t that better than just buying an expensive gun, loading it with whatever ammo you can get and then whining because the gun isn’t accurate?

60 thoughts on “They have the wrong twist rate!: Part 1

  1. B.B.,

    Wow,.. a lot to consider. I should read this several more times, but time does not permit it. It does seem that a big bore air rifle has a given “powder charge” (air burst), which will correspond to FPS given a certain weight bullet,.. and a given twist rate ( you got what you got). From there, barrel I.D. is the final element (you got what you got).

    So,… for me giving this a quick read,… and if I had a big bore,….. my question would be,.. Where does one find this Holy Grail of information? Where does one find what weight and bullet diameter to use given the charge/twist rate/barrel I.D.? A chart, a book? Black powder studies? What is going to tell me what range to start in and not start at one extreme or the other?

    I may be off base and over simplified it all,…. but this is what I gathered.

    Good Day all,……. Chris


    • Chris,

      LOL! Slow down buddy and take a breath!

      You pretty much have it, but you did leave out barrel length which in most instances is “you got what you got”. 😉 These same “rules” apply to all air rifles and also to all powder burners.

      Does the information that you are looking for reside in one certain book or on a certain published chart somewhere? Probably not. If you hunt around you will find a little bit here, a little bit there. Most of it has been gleaned from personal experiences and shared here and there.

      Something you need to keep in mind is that all air rifles, whether they are .177 or .357, will prefer different pellets. This is even true with two air rifles of the same model and caliber. This is why we try different pellets until we find “the pellet”.

      Now, knowing these “rules” will help to greatly narrow down the search. Personal experience kicks in after a bit and the lessons accelerate.


      • RR,

        I should not have even been typing that early in the morning,… but work dictates such AM rises. It is a miracle it did not come off as complete gibberish.

        My guns are all shooting well. I have done extensive testing. My biggest is the .25 M-rod. I am most interested what you will get at 100 yds. in the future,…. another 10 or 20 ten shot groups. My best ever with the M-rod was 7 at 13/16″, but have not been able to repeat it. I will say that a steel 15 oz. can be hit 8 of 10 times at 100 yds. I do need to do more extensive chrony work and shooting with it.

        You seemed to have lucked out with the pellet/bullet? choice. I want to hear some more of the same. I wish you the best and hope everything gets better or at least stays the same.


        • Chris,

          As soon as I can get some air! AARRRGGGHHHH!!!! I do have my tank now, so if I can get by a dive shop with it I can start doing a lot more extensive shooting with the HM1000X. I also have my Sun Optics spring compressor, so I can start doing some serious tuning on the sproingers.

          My chronograph and add on desiccant filter is waiting at the post office for me to pick up today on the way home, so I will be set to do some serious testing and tuning. If the #$%*&^@#$#$#!!! air compressor ever shows up I will be standing in high cotton.


    • Chris,

      You got it!

      If you are really interested in this stuff, I recommend these books:

      Blackpowder Loading Manual
      BlackPowder Handbook
      Black Powder Gun Digest.

      All are by Sam Fadala, who is also a knowledgeable airgunner. They are all published by Gun Digest.

      Gun Digest is no longer in business, but a search on Amazon or Ebay should net you all three books in good condition for $30 or so.

      B.B.


      • B.B.,

        Thank You. I do have the interest. I do not have the time or energy to devote to it though. When I “go in”,… I go (full) in. My rifles all shoot good enough for me, though I will always seek better.

        I do not see a big bore in my future,… but one never knows. I thank you for the references. I am sure that information will spur someone to delve deeper.

        My comment at such an early hour proves that your article was inspirational/thought provoking. That was maybe 1 cup of coffee. I may read at 1, but I try to hold posting to well into the second cup. 😉

        Chris


  2. BB,

    Thanks for doing this series. You have touched on all of this over the years, but it is nice to have it all brought together in a concise report.

    Long before I finally jumped into big bore I followed along as you and others gave me tidbits. I followed others on other forums as they experimented with various calibers, projectiles and power levels. Then Lloyd allowed me to play with his Rogue for a few months so I could experiment with what would and would not work.

    The world of modern airgunning has been a wonderful learning experience for me and I am still learning. My thanks to you and others for sharing with me and allowing me to share what little I have learned.


  3. B.B.

    Not sure if I got this or not….

    If a barrel has a 1:12 twist rate, one barrel 24 inches long and one barrel 3 inches long, both have a muzzle velocity of 1000 feet per second. In one the pellet/bullet makes 2 full turns in the barrel and in one the pellet/bullet makes 1/4 turn. Both spin an the same rate? What about a one inch barrel?

    What I get from this article is that you need to have a pellet/bullet that fits your barrel. How is this different that finding the right head size for an air gun pellet? If it don’t fit right, it won’t shoot right! That is what I get out of it anyway….

    -Y


  4. B.B.,
    Great article! Another one to add to my note book.
    Bullet length.
    Got a stupid question for you. let’s say you shoot a 400gr .45cal. Bullet in say a Texan and can group 5 shots in 8 inches @ 100yds.now Harry Potter comes along and takes that same bullet and reduces the weight by 1/3 rd . Do think that you might reasonably expect that gun+bullet combination to have the same accuracy at say 125-150 yds.
    Let us assume the bullet shape remains the same.
    You might not be able to throw a 10lb lead ball not more than 30ft (not too accurately) but you might be able throw a 7lb javelin 50ft and be more accurate.
    I have to stop drinking this darned Italian coffee.Too much caffeine.Lol!

    Pete


  5. 1:12 is the most common twist rate for air guns. When would a 1:10 twist rate be more appropriate? A faster/slower pellet/bullet? A larger/smaller gain pellet/bullet? 1:14 rate?

    Thanks,

    Yogi
    ps I have your barrel harmonics article ear marked to re-read.


  6. BB
    Thank you for some great information. My take away is that my air gun shoots a 25.4 grain pellet very accuratly at 800fps. The reason it does not do well with a 34 grain pellet is because it is sent down range at 720fps and the spin is not fast enough to be stable. I will ponder on this all day.


  7. Great stuff!!!

    I have an adjustable “rifling jig” project that I work on when I have time so this is great information!

    I have started experimenting with spin stabilizing potato “wad-cutters” from my pneumatic and propellant powered “spud guns” to see how accurate I can make them. Fun stuff!

    Thanks BB!

    Hank


  8. Big bores and ultra powerful air rifles concern me, it seems to be pulling away from the core ability of the sub 20ft/lbs airguns we’ve all traditionally used as not only an alternative to 22lr pest control but the better alternative with small pests.
    Their, by and large, sub lethality for anything bigger than a rabbit has meant a total lack of regulation, if you’re a felon, no problem, in your suburban garden, no problem.
    Sooner or later someone is going to kill a few people with a 357 or even a powerful 25 (and they will) and its going to be a game changer and you just know any legislation is going to be so broad handed its going to affect all airguns in the states.
    Secondly, hog or deer hunting, do you need a big bore airgun?, of course not, a cheaper, more efficient .270 centre fire will do the job far, far more ethically, not to mention having as many follow up shots as your pocket can carry, without tanks etc, and we’ve had those for years, big bore airguns are an answer to a non existing question. Sometimes human curiosity about whether it can be done, overcomes any thought of whether it should be.
    Proceed down this technological path with some caution because at the moment nobody is looking left and right.


    • Dom,

      Please bear in mind that the lower-powered airguns of today are a recent invention. Big bores have existed since the airgun started, back in the 1500s.

      A lot of people feel the same as you — that big bores put us on the slippery slope. But the truth is, we are already on that slope and have been since the early part of the 20th century. Your own country is a prime example of that — not just with guns, but even with knives. I refer to the initiatives to make even tableware controlled. Perhaps these are fringe initiatives today, but 30 years ago what is common today was considered fringe.

      My belief is the only thing we can do is get right back in the faces of the radical left and push as hard as we can. Here in the U.S. the radical left has come out into the light after the Trump election, giving the public the view that conservatives always maintained was the truth.

      I’m not surrendering any of my rights, regardless of what Hollywood or the radical leftist media says.

      My two cents.

      B.B.


      • Yeah, I’m not getting into the politics of things, it’s actually a very different culture over here, for many reasons, not least of which is that because of our disproportionate population density and military size, most of us are in, or have many friends in the services or government security or local politics so we don’t really feel the us and them division as much as the States seem to, in short, the them tends to be us if you know what I mean.
        Jackbooted thugs can march up my path if they want, I’ll know their mother and will possibly punch them in the face up the pub on Friday night 🙂
        We are also massively densely populated, even if I could go out on public land with an AR15, by the end of the day I’d have scored several dog walkers and hikers, so the two cultures aren’t necessarily as comparable as both sides of the control debate would like to think.
        If your kids were playing in the garden would you be happy with someone shooting say a 22WMR the other side of the fence?, because if it was legal some dumbass inevitably would with the predictable results, if you had no legal precedence to stop their behaviour I think you would be happy, especially if there was injury or death if there was, and with firearms within city boundaries, in most states there is.
        The same will eventually happen with hyper powerful airguns, and with the first kid who’s brains are blown all over the trampoline, rightly so….its s matter of time.
        The problem with the pro gun lobby is that it tends to knee jerk too much, you elect the local government to enact the sort of legislation that is designed to assist at least in your safety, and, by and large it works.
        The problem with the gun control lobby is one of over simplification, even without waffling on about amendments (soon removed the prohibition one when it suited) there are simply too many guns already out there in illegal hands for starters and secondly a good third of the shocking death statistics are concentrated in some very small communities and not relevent to thr broader populace and about 10% of the remaining figure are suicides, that you have to imagine would have been achieved by other means so the figures are skewed, there are statistics, statistics and damn lies as the saying goes.
        Still, there has to be some way of limiting the accident rate and the hive of gangsters coming up north and buying guns from people off Craigslist out of the back of pickup trucks and ferrying them back to the ghetto.
        And training and good moral fibre isn’t going to do it, never will all the time there are stupid or moral free individuals around.
        I’m personally quite glad my street isn’t full of magnums, most of the guys here spend the weekend drunkenly punching lumps off each other with the odd knife and brickbat, (an English pastime, don’t believe Downtown Abbey lol) sometimes sheer fatigue seems to be the only thing that makes them shamble home, I certainly don’t want anything made easier 🙂


        • Not to seem stoic or uncaring, but we’ve had crazies storm schools and shoot kids. We still stonewall any action against guns. I’m not convinced a killing with an airgun will be enough to actually move any serious legal action. Crazies will kill people with knives, trucks, fertilizer, hammers and whatever else is available. Trying to quash peoples ability to cause harm to others works about as well as draining the ocean.


          • Worked pretty well here and in Australia, but, I reiterate, very different cultures.
            Besides I’m talking more about accidents from misuse or carelessness, and the fact that big bore airguns bring precisely nothing to the table that wasn’t there in a more efficient form in a centre fire.


            • Airguns are un-regulated, bigbore ammo is still fairly cheap in comparison. They are comparatively quiet to a .270, my bulldog is for sure. They don’t recoil violently. Efficiency isn’t the only factor. A shotgun is better for squirrel, but people still love to use .22LR and pellet rifles. Center fires are exceptional at killing larger animals, but people still use bow’s and arrows.

              The cross ownership of airguns and firearms is common in the states. Just because something is powerful doesn’t mean it should be illegal.


              • Is this a deliberate misunderstanding of absolutely everything I say?
                I’m talking about the lack of lethality of airguns, meaning they remain unregulated, now they are developing into far more lethal items, then you may see some regulation
                Which might be worth it if there was a lack of things to kill boar and deer with, however a big bore airgun (like a bow) is a truly awful choice to hunt with by comparison with centre fire rifles.
                I’ll duck out of this conversation because its running, predictably, like every discussion where regulation and firearms are mentioned (even if in a totally different context) in the same sentence into everyone going purple, snorting about cold dead hands and arming the geography teacher with an AK


          • Auronotcs,

            Good point!

            Metal detectors and police at the entrance don’t seem to do any good. Why not allow the teacher and worked who qualify, carry on campus? Several Texas systems are looking into this right now.

            If you can’t prevent the crazies, at least defend against them.

            B.B.


        • Dom, at the end of the day, I don’t think it really matters where you live or what you do. There will always be people that want to take away your rights. You can’t make them happy. You have to push back. Best of the day to you!

          Mike



  9. B.B.
    Correct if I am mistaken, though is not this just the bare basics of shooting anything?

    I did not know that there are air gunners that did not know this, the same issues exist now in small bore air rifles do to insainly heavy “pellets” (bullets) in .177 and .22 caliber. You need to get the 15 grain and heavier .177 bullets up to some speed to stabilize for a good reason, same goes for the 30 grain plus .22 caliber pellets.


  10. B.B.,

    Of course accuracy is paramount, but provided the shooter is hitting the target (and the target is game), maybe the hunter simply needs to be much closer to the hunted and give up this need for speed. I thought shooting was only one small part of the hunting puzzle, although I quickly point out I am not a hunter.

    I do not mean to be an advertisement for Mr. Hollowpoint, but all over his website he points out that unless a customer specifically orders a “hard” bullet, his products are all basically “pure lead goodness,” as I believe he describes it. He provides many photos of his products, one a lead alloy, the other his standard pure lead,both cast from the same mold, shot with the same big bore into the same slab of ballistic gel, and in most photos the harder one is barely deformed. But the lead one is so mushroomed, it is sometimes difficult to see any cylindrical shape left. A pure lead .50 ends up more than an inch across.

    I’m not a hunter, but if I were, I know what I would prefer.

    Michael


    • Michael,

      Without question, Mr. Hollowpoint “gets it.” His bullets are made from soft lead that he takes the extra time to cast. He understands everything I have written today.

      Another company that understands is Tin Starr Bullets. They also take the extra time and care to cast soft.

      You know, if I wasn’t right about this harness thing, neither company would bother, because casting soft lead does slow down the process quite a bit.

      B.B.


  11. The question in black powder has always been “Do you want to shoot roundball or do you want to shoot bullets?” If the answer was roundball, then you got a twist from 1/56 to 1/72 or slower. If you wanted to shoot bullets then you went from 1/21 or faster. Does this make a difference in big bore air guns since the MV is slow to begin with?


  12. B.B., wow, a lot to chew on there. I know when I used to shoot black powder a lot, my round ball shooters were long barrels with a 1:66″ twist. That seemed best for round ball. The all purpose twist was 1:48″ (for both conical and round ball) but like most things, this twist seemed like a trade off. If in black powder world of rifles, 1:66″ is best for round balls, how so then, when looking at the ammo for the big bore air guns, does the round ball work for one designed to shoot bullets? I would assume they would not be very accurate with round balls? Could this also be why I’ve not had much luck shooting .177 and .22 round balls from my air rifles? Could it be with the right twist rate the round ball in a “pellet” rifle could shoot accurately, like a round ball black powder rifle can? Hmmm..

    Doc


  13. DOM, I see your point about the population density of the UK. However, I don’t see your point about banning something cuz it might possibly hurt somebody in the future. By that line of reasoning to, I might as well sell my car. If I wanted to wreak havoc, I’d much rather have the 270 you mentioned. The ammunition and the 270 are much easier to get a hold of than a big bore airgun. Sounds like nanny government to me


    • Well no, that’s a bit of a straw man argument, you are forced by law to follow some very stringent tests to operate a car, you are forced to register it, insure it, transfer registration upon sale etc, it’s primary purpose is not that of say, a Glock who’s primary design is to kill humans.
      But that’s not my argument (maybe the NRA should hold registration and you should be forced to take a full test insure and transfer all firearms just like a car, you tell me)
      My main issue is legislation, at the moment you can’t fire your barrat 50 cal in your suburban garden, not even in Texas, its not too neighbour friendly and its understandable as a law. The quiet and low powered airgun you are allowed, if you make them centre fire loud and powerful, even rimfire, you could invite the same legislation, for the same reason, and, to be fair probably rightly so.
      However, Governments are slapdash with this sort of legislation and it may well end up affecting the moderately powered airguns we traditionally used.
      I don’t think this will happen soon, it’ll happen when you can buy a 100ft/lb 357 cal that can apply 6 shots in a reasonably sized package for $300. And that will come.
      That could be a game changer for the federal view of airguns, especially if its misused by somebody.


      • And they definitely won’t ban anything that might hurt someone in the future, but they may restrict where you can shoot them or put in power limits AFTER its hurt people
        Unlikely with a 20fpe 22 springer, and very possible with a 150fpe 357 PCP
        Which is kinda my point


      • Dom,

        I wish somebody could explain this to me:
        If I live in the USA, I am not allowed to export “optical sighting devices”. Last I looked, most are made in China, Japan, Philippines, Korea, Germany. There is only one company that I know of that “makes” their scopes here. If I am a bad guy living outside the USA, I have no problem sourcing “optical sighting devices”…Makes sense to somebody, just not me.

        -Y


        • No, and that’s precisely my point, low powered airguns may end up being legislated against, as part of what you bring upon yourself with ultra high powered ones, ie, the same regulations as firearms.
          The USA silencer laws are a bit crazy too, they are positively encouraged for firearms over here in the UK but over there you have to jump through hoops.
          Over here black powder and ISSF pistol target shooting suffered badly and unnecessarily in the tightening up of the laws after the massacres, all governments seem to be ridiculously.broad with legislation and some of it is absurd



  14. Hm. This reloader always thought that spin rate was tied to the weight of the bullet not its length. But given that the diameter is fixed, does length and weight amount to the same thing? Since I only shoot targets, I’ve never paid much attention to the interior of the bullet and whether it is core-lokt, differentially weighted, contains spaces, or even is full of powder. Are there designs that significantly change the bullet density within its volume or is that pretty fixed?

    FrankBpc, thanks so much for your advice. I have longed to have a master sharpener at my elbow and this is the next best thing. What you say has the reassuring sound of a pro, a lot like blog reader Victor on shooting technique. I am indeed working freehand. I think what happened is that through intuition, luck, and continual practice, I happened to bring everything together. But then I slacked off for awhile which is when my problems began to appear. As Sylvester Stallone says in Cliffhanger, “You just lose the feel.” Now, I don’t know how to find my way back. This is not unlike my early disastrous shooting career on my high school rifle team. I started out as a prodigy, but one day, I became self-conscious. And without any experience, maturity, or technical foundation, I took a long slide into oblivion. I only built myself back up years later with 100,000+ shots from an airgun, and I guess I will have to do the same with the knife sharpening.

    Using the sharpie is a technique I’ve heard of but never tried. So what exactly am I looking for? The sharpie should be rubbed off some distance from the edge. Is that right? What will it look like when it’s wrong? Also, I use Japanese water stones, so will the water wash off the ink from the blade? I don’t know about a permanent marker since I don’t want to mark up my blades. Thanks for the advice! I’ll follow up by email assuming you are using the same one as before. Oh, and I’m set with my magnifier which I’ve enjoyed using with my new bore light to examine the bores of my guns. Some bores are truly mirror-bright and others are definitely not.

    Matt61



    • as you start to get into, monlithic or” guilding” metal bullets. your bullet length as opposed to same weight lead is going to increase. while the increase in velocity will make up for some of this, it is not always enough, so you still need to compensate with a faster twist



  15. BB,

    I would strongly suggest that you immediately buy that compressor. I have preordered one. It was supposed to be in stock tomorrow. This morning it was moved out to next week. This afternoon they moved it out to the end of April. It looks like I may have to shop for an air compressor elsewhere.


    • RR,

      Patience! If this one holds up as well as B.B.’s 2nd. hand used one,…. you might have a real winner. B.B. said the Omega is having issues. I would roll the dice and do the A.V. if I was in your position of a first time buyer. Time will tell.

      I would like to hear rebuild times and cost. I would find that out. It would also be interesting to hear the cost of an a Omega rebuild and time frame/life.


      • Chris,

        The way this is going it will be December 32, 2048 before they get any in stock. 😉

        I guess I just get pretty burned that PA will advertise and sell something they don’t have.


        • RR,

          Perhaps B.B. could share some news of the demand for the A.V. both from P.A. and A.V. ?,.. after a call or two. A.V. and their China Mfgr. could be swamped at the moment ?,… I do not know.

          P.A. is a retailer at the supplier’s mercy. As for back orders,… I,.. as I am sure you too,… have seen this in the past. Pellets for one. Common ones like JSB 15.89 and 18.13’s. I remember watching the 499 for month’s. No sooner did P.A. get a batch and they were gone! I am talking like in a day or two. I finally did a pre-order.

          It is up to you to wait or not. Me,… I would. Meanwhile,.. keep your ear to the ground on the A.V. reviews (here and else ware) and any issues that may be creeping up. Just my 2 cents.


          • Chris,

            Yes, yes, yes, I understand all this and I have experienced such with PA and others before. In this case, they never had it to begin with.

            $%^@*@#$%&!!! I want my new shiny toy now!


  16. Fun read. The Greenhill formula is also a fun read and has been applicable for many years. Certain varibles had to be dialed in for modern high speed firearms and bullets not being made of lead. I have a blackpowder gun that I bought specifically to shoot the bullet I chose first. I would love to see if the Greenhill formula applies to the diablo style pellet.


  17. Wow.. I was living I stone age.. Very informative… Please correct me if I am wrong

    Summary
    (keeping gun power constant)
    More twist rate, more spin, more stability
    More muzzle velocity (due to power) , more spin, more stability
    More bullet length or diameter, lesser muzzle velocity (due to increased weight) lesser spin rate, lesser stability
    For a particular twist rate and power, we need to match bullet length and diameter, in short bullet weight

    My question is that air gunners are not available with much if the option other than increasing power or increasing the Barrel length.. I understood the power effect but how does length help when you earlier mentioned that length has nothing to do with twist rate


    • Amaranthine-mystery,

      Welcome to the blog.

      That is overstating it. A bullet can also be over-stabilized and less accurate. And, an under-stabilized bullet may still be accurate for some distance before it destabilizes too much.

      Then you said “For a particular twist rate and power, we need to match bullet length and diameter, in short bullet weight” That is correct, except the shape of the bullet can also move the weight to the wrong place. A spitzer (pointed) bullet weighing 87 grains may be less stable and less accurate than a round nosed bullet of the same weight.

      Barrel length can speed up a pellet in a PCP, or slow it down in a springer. So sometimes barrel length is useful and other times it isn’t.

      B.B.


  18. B.B
    Amazing… Once again grateful for your quick reply and guidance… Understood the concept of shape shifting the weight… And under stabilized and over stabilized bullet.. Didn’t have any clue earlier about over stabilized bullet…
    Which airgun should I go for to have a kill (deer) at 250m… Is it possible? Kindly recommend the pellet/cast bullet which will be effective and stabilized (coz stabilization is damm difficul subject) … Is hatsan Hercules Bully capable? (sorry for being little off topic)


  19. Amaranthine-Mystery,

    Forget any big bore that doesn’t produce a lot of energy at the muzzle. To kill a deer at 250 yards takes a rifle that can group inside 8 inches at that distance with you on the trigger. Only a few I’ve seen can do that. The Texan would be a good choice.

    All that said, large animals have been taken with airguns at ranges beyond 200 yards. I would never attempt a shot like that, but some do.

    B.B.


    • BB
      Got it sir… Texan it is.. And your advice noted for 200 yards (may not be an ethical kill).. once again thanks for your time and guidance… Looking forward to more of your amazing articles..


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