Rifling twist-rate primer: Part 1

by Tom Gaylord, a.k.a. B.B. Pelletier

Recently, we have had a number of questions about rifling twist rates that were attached to the twist-rate report. These questions are extremely important to the understanding of how bullets and pellets are stabilized, so I’m starting a tutorial on rifling twists today. I’ll keep adding sections as I see the need to explain more about the topic.

Today, I want to lay a basic foundation of what the rifling twist rate does. Blog reader Feinwerk asked if centerfire rifles (he said higher-power firearm rifles) had different twist rates than rimfire rifles, and the answer is yes. I’ll get to that, but let me start at a time when things were much simpler.

Early firearms shot multiple projectiles, similar to today’s shotguns that shoot birdshot and buckshot, but much cruder. It wasn’t long before people started experimenting with single projectiles. They found that single projectiles retained more of their initial energy than many smaller projectiles, so they did more damage when they connected with a target. The problem was getting them to connect.

After much experimentation, people discovered that spherical projectiles were the best for firearms. They flew the straightest because they didn’t have the irregular surfaces that created low-pressure zones to guide the bullet astray.

Then, rifling was discovered. Straight rifling (straight lands running parallel to the axis of the bore) was first used as a means of holding all the unburned gunpowder residue, of which there was much. That allowed the gun to be fired more times before cleaning. And, at some point, someone cut the grooves in a spiral — to make them longer to hold even more residue? We’ll never know for sure.

Once people saw how much straighter a spinning ball flew compared to one that was not spun intentionally, the race was on. For hundreds of years, the spinning round ball was the only bullet that was known. It reached its zenith as the patched ball used in the American rifle we know as the Kentucky — where the rifling doesn’t even engrave the lead ball, but spins it by spinning a cloth or leather patch that holds the ball tight while it’s inside the barrel. The ball gets very little distortion from the barrel — although there is a pattern around its circumference where the rifling pressed against the patched ball.

When the patched ball exits the muzzle, the patch falls away and only the bullet travels on to the target. Accuracy increased with this system, and the loading time dropped because the shooter didn’t have to engrave the lead bullet with the rifling when he loaded the bullet/ball.

The conical bullet
Things never stand still, though, and after the patched ball came into general use shooters began experimenting with bullets that were not balls, but rather longer cylinders of lead. These were the first conical bullets.

ball and conical bullet
Although the round ball is very close to the same diameter as the conical bullet, it takes a lot more spin to stabilize the longer, heavier conical bullet.

A ball doesn’t need to spin very fast to be stable because its surface is smooth and regular. A conical bullet, on the other hand, is irregular — being longer than it is wide. Instead of a ball, it’s more like a spinning top that can balance only on its point as long as it spins fast enough. The longer the bullet, the faster it has to spin to remain pointed forward in flight. This attitude is called stability. If the bullet isn’t spun fast enough to remain point-forward, it’ll wobble like a top slowing down; and the varying air pressure that’s created will quickly cause it to tumble in flight. When that happens, the bullet will stray off its straight path.

Twist rate
This is when barrel makers began to be interested in the twist rates of their rifling. Prior to this time, they simply rifled the barrel with whatever twist rate their machinery supported. It’s a fact that the Hawken brothers rifled all their plains rifles with a 1:48″ twist, regardless of what caliber they happened to be.

With conicals, though, the twist rate does matter. Too slow and the bullet tumbles. Too fast and — well, less is known about what happens when the twist rate is too fast; but in my experience, you’re never able to get the same accuracy that you can when the twist rate is just right. A rifle that puts 10 shots into a half-inch with the right twist rate and bullet may put 10 of a different bullet that’s both lighter and shorter (and therefore both moving and spinning faster) into 1.5 inches.

The length of the barrel does not change the twist rate, nor its effect on the bullet — at least not directly. But a longer barrel sometimes does increase velocity. This is always true when black powder is used and can also be true when slower-burning smokeless powders are used.

A bullet that exits the bore of a barrel (of any length) with a 1:12″ twist rate and is traveling 1,200 f.p.s. is spinning at the rate of 1,200 revolutions per second (RPS). Speed that bullet up to 2,400 f.p.s. as it leaves the muzzle, and you increase the bullet’s spin to 2,400 RPS.

If a longer barrel causes an increase in muzzle velocity, it also causes an increase in the rotation rate of the bullet once it leaves the barrel. It does not change the barrel’s twist rate; but because the bullet is going faster; it’s also spinning faster. Reloaders take that into account when they load their cartridges. It’s possible to drive certain bullets too fast or too slow, resulting in less accuracy. Reloading is about finding a balance between the bullet and the velocity at which you launch it.

The M16
The most public and classic case of twist rates and their effects was the launch of the M16 rifle to the U.S. military. It addresses the specific question that Feinwerk asked. The early developers of the 5.56mm cartridge selected a twist rate of 1:14″ because the bullet was barely stable and would tumble and destroy flesh fast when it impacted a body. But they were focused only on the cartridge’s use in Vietnam — a conflict that was mostly conducted at short range and in very warm weather. The 1:14″ twist rate was too slow to stabilize the bullet properly beyond about 250 yards or in very cold weather. It worked great for a 40-grain .224-caliber bullet moving 4,000 f.p.s. from a .220 Swift, but was horrible when used with a 52-grain .224-caliber bullet moving 3,200 f.p.s from an M16.

Don’t confuse the caliber size in inches (.224″) with the name of the cartridge. Both the .220 Swift cartridge and the 5.56mm cartridge (M16) use the same .224″ bullets.

The twist rate for the M16 was increased to 1:12 inches, which worked better, but in time even that rate was discovered to be too slow to do everything the military wanted. Today, the twist rate for an M16 variant rifle runs anywhere from 1:7″ to 1:10″…depending on the specific model of gun, when it was made, which service owns it and what kind of ammunition it’s expected to shoot.

And the answer, Feinwerk, is yes…the twist rate of centerfire rifles does vary by caliber, by the bullets used and the velocities at which they’re driven.

This first twist-rate primer report was written at a very high level. I don’t know whether or not it addresses everything you wanted to know, so I’ll read your comments with interest. If we need to go into greater detail, that’s always possible. Otherwise, I’ll remain at this overview level in the next report.

44 Responses to “Rifling twist-rate primer: Part 1”

  • Gunfun1 Says:

    Excellent read. This is the stuff I like. I know you said in the past that the blogs are getting more and more technical. And I tend to over do it always when I comment. So I was going to hang back a bit before I commented today. (I re-read my comment and look at me again).

    But I figured I would throw out a little more info out about me. I mentioned before that we make projectiles of various rounds for the military. But didn’t mention we also made ground support equipment and flight simulators for various aircraft(or maybe I did ?). We even made some uppers and lowers for different guns at times. And flight parts for F18′s. (Talk about a paper trail for a aileron hinge). And a little while back we got a contract(small contract) for the Barret .50 cal. bolts.

    But one of the things that came up in the recent past was changing the tolerances of certain characteristics of the projectiles because they were testing different barrel designs. So they would send us various projectiles back so we could see if changes needed to be made to the projectile for that particular barrel they tested.

    They (wouldn’t) give us specifics of what twist the barrel was our how deep the grooves were cut or how many fps the projectile was moving at. But some of the projectiles I seen were just way tore up on the outside diameter.

    And again this is just me running on again. But I guess what I’m relating this to is what you talked about first. Which was the bullet/projectile or whatever we want to call it.

    How it sealed to the rifling twist of the barrel. Not looking for a detailed explanation but something maybe a newbie could relate to. Above was kind of leaning towards firearms.

    Here is the question relating it to airguns. There’s many features in the common pellet.
    But the skirt at the back of the pellet seals to the rifling when the gun fires.

    So do the manufactures of airgun barrels have a different set of rules they follow with the width of the land and depth that it is to help seal the pellet ? I realy don’t know; haven’t looked that deep into it.

    Like I said above the projectiles I seen was just way tore up. They had the projectile to loose or the twist too aggressive among other causes I guess with the barrel designs they were trying.
    I don’t know ?

    Sorry if you covered this before but didn’t go looking back trying to find the info.
    I say let it go and start schooling. I’m always interested in more info.

    • B.B. Pelletier Says:

      Gunfun1,

      I will answer one question that I see for sure in your comment. Do airgun manufacturers have specific land width and depth? Yes, they do. Most airgun barrels are made with 12 lands these days. They have to be narrow because there are so many of them, but even when there are just 6 the lands are always narrow and shallow. How shallow? Around 0.002″ or so. It does vary from maker to maker, but shallow thin lands are the norm for most airgun barrels today.

      B.B.

      • Robert From Arcade Says:

        So BB , what would it take for Crosman to build a repeating pcp or msp .30 cal with a 1:30 RH twist barrel for the .310 dia round ball ? Nothing tech like, no on board computers, usp port or anything expensive. Just borrow the magazine idea from the old lever action 99 ,or the removeable one from the 400 CO2 bolt rifle , and use the Marauder /Discovery platform. Then I could retire my TC Cherokee and never have to clean up black powder residue again,and(!) it could be a repeater . We need this, as practically speaking,there is NO RF ammo available here now .

        • B.B. Pelletier Says:

          Robert,

          I have seen .310 ball shooters that are single-shot and they aren’t much. Very limited range, due to inaccuracy.

          B.B.

      • Gunfun1 Says:

        I have the barrel off of my .177 Marauder right now. And I held it up to the light and the rifling is definitely not as defined. The reason I asked about that is you talked before about deep seating pellets on certain guns.
        I’m guessing that deep seating is probably helping the skirt to engage to the rifling and maybe helps seal the air-charge better ?

      • Cole Says:

        How many lands are on firearm barrels? does it vary gun to gun like twist rate

      • Wulfraed Says:

        Heh… Consider the old Marlin “micro-groove” rifling on the variants of the model 60 .22LR…

        As I recall, they were advertised as eighteen grooves.

  • B.B. Pelletier Says:

    This was sent to me directly, instead of being posted. So I am posting it for the reader:

    hi there
    just wanted to say that your post helped me with my ruger blackhawk airgun. i had the exact same thing happening of the barrel snapping up and bending. i was very mad at first and was about to buy a new barrel for it online and decided to do research. first try i bent it back and looks straight again. was suprised that metal like that can bent, would have never thought. anyway i was very happy that it worked thanks to your post.

    sincerely,dennis

  • TC Says:

    BB,
    How does the rifle manufacturer’s design/engineering department determine the optimum twist rates? Is this trial and error, years of experience, or are there sophisticated formulas?

    • B.B. Pelletier Says:

      TC,

      There is a formula called the Greenhill formula that has been around for over 100 years. It helps, but really we know so much about twist rates today that people pretty much know what each bullet requires.

      B.B.

  • Michael Says:

    B.B.,

    Slightly off-topic, but reading this got me thinking about the Crosman MK-177 I recently recieved from Pyramyd Air. It’s basically the classic 760 dressed up as an FN SCAR. Like a number of pellet/BB combination guns, it has the advertised ability to shoot steel BBs along with lead pellets and (4.4mm) lead balls.

    It’s a lot of fun and the same inside as my Crosman M4-177, but I hesitate to shoot steel BBs in it for fear of damaging the rifling. How can it have rifling that is supposedly impervious to damage from steel BBs?

    Michael

    • Michael,

      B.B. is at the range right now, but I think I can answer your question. Others have asked the same thing, and B.B. previously responded that he thinks today’s rifled barrels may be made in such a way that steel BBs don’t do as much or even any damage to them. I’m sure he’ll provide a more detailed answer when he gets back this afternoon.

      Edith

    • Robert from Arcade Says:

      Mike: I’ll throw my 2-cents in, the regular steel bbs are under size and that’s why there’s a magnet on the bolt probe of you gun . Otherwise the bbs would just roll out the barrel. Basically a regular steel bb just bounces down the barrel. Pellets are more accurate even in a smooth bore bb gun. My old Benjamin 130 pistol with a smooth bore will shoot pellets into a 1″-1 1/2″ group at 30 feet. Steel bbs will ruin the rifled bore eventually , and if your gun shoots a pellet well, I’d stick with only them. That said ,I’m addicted to plinking with CO2 bb pistols,especially the replicas. Most of those are smooth bores. Round lead bb shotgun shot was around .178 in dia. and sometimes will prove accurate as pellets at short ranges. Steel bbs are .173 in dia. by comparison. Hope this helps.

      • Fred DPRoNJ Says:

        and allow me to add another penny to this. The steel used in rifle barrels is fairly mild – soft. I discovered this when I went to re-crown a Benjamin Nitro and did an article for the blog. My file drawing across the muzzle, bit into this steel like the proverbial knife through butter. I suspect all rifle barrels and I’m including rimfire and centerfire barrels, are made of this mild steel and not hardened. Otherwise, why only do we shoot lead or copper jacketed bullets and not steel? I suspect a steel BB would damage the lands and grooves in these barrels eventually, as well.

        Fred DPRoNJ

      • Michael Says:

        Robert,

        The round shot I described is not .178 but graphite coated and copper coated lead precision shot in 4.4mm/.173. I also have precision lead round balls in 4.35/.171, 4.45mm/.175, 4.5mm/.177, and 4.54mm/.179.

        The 4.45 stuff is great for muzzle-loading in my Daisy 25 and my Hahn Super Repeater! The smaller stuff I use in a top-bolt springer by Haenel.

        Fred and Edith, maybe what B.B. is referring to in the new rifling has little to do with the hardness of the steel but rather the shape of the rifling lands themselves. Maybe the rifling is especially pronounced rifling, with extra sharp lands and extra deep grooves. I believe this is called “polygonal rifling.”

        That’s the only thing I can think of, anyway.

        Michael

        • Robert from Arcade Says:

          Mike; I’d be interested on how the .177 and .179 lead balls shot in your gun. I’ve got some old Beeman 4.5mm (so it says on the tin) precision RB in that really only measures .171-.173 . It just rolls out of my 130 Benji’s barrel. Some of the msp rifles like the 2100 Crosman are a pain to load pellets into. The one I have is quite accurate ,but you have to have dwarf fingers to load it. Pellets are always flipping the wrong way around.

          • Michael Says:

            Robert,

            I have a Benjamin “Benjamin Franklin” 130, and the 4.35, 4.40, and 4.45 simply roll through the barrel. I have 4.5 by Gamo (coated lead) and Haendler and Natermann (graphite coated lead and copper plated lead). All three do well in the 130, of course at round ball pistol distances, 20 feet at the most for targets and small spinners. The 4.5 size is large enough not to roll more than a centimeter past the breech. If I try to muzzle load one, it requires a light push with a dowel rod to get it to the breech.

            The H&N 4.55 are just a smidgeon too big, too tight to try to ramrod one. (I was incorrect above about their being 5.54. They are marked 4.55mm on the tin, whether it is the export one P.A. sells or the German one with the whole label ein Deutsch) They do NOT work in my 130, although I’d bet a 4.53 round ball would. I am certain a 4.52 round ball would.

            I am curious as to how well a 137 might do with these lead round balls, but then again, if one has a 137, why not just put a pellet in it? :^)

            Michael

            • Robert from Arcade Says:

              Mike, thanks for that information about your results with the 130 and lead RB,much appreciated.

        • B.B. Pelletier Says:

          Michael,

          Yes, I do believe that some airguns use a polygonal rifling to minimize BB damage.

          B.B.

        • Duane Says:

          Actually “Polygonal” rifling does not use lands and grooves. Where normal land and groove rifling has 2 or more sharp edged grooves spiraling down a round interior bore, polygonal rifling has a barrel interior profile that is a polygon rather than round. For instance my Desert Eagle has a Polygonal barrel.
          http://en.wikipedia.org/wiki/Polygonal_rifling

    • B.B. Pelletier Says:

      Michael,

      Edith answered as I would have.

      B.B.

  • Willmore Says:

    B.B.,

    To answer your pondering: “And, at some point, someone cut the grooves in a spiral — to make them longer to hold even more residue? We’ll never know for sure.”

    Is that, no, they didn’t because a spiral groove has no more volume than a straight groove. Think of taking a square and skewing it to the side. Then think of it as two right triangles. The formula for the area of the square is b * h. For the two right triangles it’s 2 ( 1/2 * b * h) which equals b * h.

    If you take the inside of the barrel and lay it out flat, you can see that the grooves of the straight cut barrel are just long rectangles while the spiral cut grooves are parallelagrams–and they the math above applies.

    So, if they cut them in spirals for the purpose of getting more volume for unburnt powder, they failed at that task because it didn’t increase that volume. I guess that doesn’t mean that they didn’t *mean it to*, just that it didn’t do it.

    • Matt61 Says:

      I don’t agree with this. Given a barrel, if you cut a straight groove parallel to the bore axis, the length of it will evidently be less than the arclength of a spiral groove cut down the length of that barrel. And since the volume of the groove is dependent on the length that will be greater as well.

      Your argument about distorting the square into a parallelogram is interesting. I suspect that you can construct a parallelogram to be equivalent in area to a square but that may not represent the same area of the original square under this skewing operation that you describe.

      Another geometric comparison may make this clearer. As we discussed some time ago in talking about twist rates, if a barrel is slit down its length and laid flat, it would look like a rectangle. The spiral groove would now look like the diagonal of that rectangle (for an appropriately chosen section of the barrel). A straight groove down the barrel would look like the length of that rectangle. The diagonal of a rectangle is longer than the side according to the Pythagorean theorem.

      Matt61

      • Willmore Says:

        Matt61, B.B;

        Thanks for the replies.

        If you cut a grove spiral groove, it will, indeed be longer than a straight groove. We agree there. What I think you’re missing is that the groove will be narrower than the straight cut groove. That may not be intuitive, but I managed to munge together a drawing: http://i.imgur.com/WvvV1B8.png

        For the square ABCD, if AB is length 1, then the area is 1*1 or 1, right? For the skewed square–a right parallelagram to simplify things–the area is 2*(1/2*1*1) or 1.

        For a straight groove, the width is 1 while the length is the length of the barrel A=1*length.
        For a spiral groove, look at triangle AED. Since the width of the spiral is the length ED which we can see is < the length AD which is 1.

        Specifically, length ED is 1/sqrt(2). If we cut off triangle AED and paste it so that the AD side is attached to BC, you can see we now have a rectangle of width ED and length CD, yes? ED= 1/sqrt(2) and CD is sqrt(2), so the area is 1/sqrt(2) * sqrt(2) or '1'. The spiral groove will have the same area as the straight groove.

        This all assumes that the mandril used to cut the grooves doesn't change between the straight and spiral cuts–e.g. if you cut through both barallels perpendicular to the axis, you'll see the same profile. Which seems a reasonable assumption.

        Extending this proof to arbitrary twist rates is left as an exercise for the student. :)

        • Wulfraed Says:

          What I think you’re missing is that the groove will be narrower than the straight cut groove.

          Why? You are assuming what would be taking a straight barrel and twisting it to make spiral rifling.

          But is your cutter is , say, 0.005″ wide, it doesn’t matter if the cutter is drawn straight down the bore, or slowly rotated as it is drawn — the cutter is still 0.005″ in the perpendicular to the bore.

          The cutter isn’t somehow rotated to be perpendicular to the line of the rifling.

          _
          _
          _
          _

          vs
          _
           _
            _
             _

          (if the forum software doesn’t trim out the leading spaces)

          • Willmore Says:

            Wulfread,

            That’s exactly the point. Take a look at my diagram. The width of the cutting tool stays perpendicular to the axis of the barrel regardless of if it’s rotates, just like you say. But, if you draw it with rotation then the width of the cut groove will end up narrower–the cutter is the line AD while the width is ED which is narrower. If the cutting tips were somehow tilted, then ED would be the same length as AD.

    • B.B. Pelletier Says:

      Willmore,

      All you have to do is wrap string around a dowel and then measure it. If it is longer than the dowel, which it will be, then a spiral is longer than a straight line, which is what rifling is that is parallel to the axis of the bore.

      B.B.

      • Michael Says:

        B.B.,

        That s an excellent analogy.

        It actually reminds me of this old chestnut: About how many grooves are on the typical LP record? Answer: Two.

        Michael

  • Matt61 Says:

    B.B., great summary of the history of rifling. But I wonder if the experiment with the shape of the projectile didn’t begin much earlier. Isn’t it true that bullets for slings of the David and Goliath design were not spherical but more ellipsoid? I wish I could remember. In reading about this, I focused more on the way these bullets were inscribed with sayings like “Ouch” or “Take that.” :-) Anyway, it is entirely possible that the discoveries about shape were repeated with firearms as you describe.

    Wulfraed, yes I saw the x’s and o’s in your diagram, but I still think that color has more power to express. That is a central tenet of the field of data visualization. And did I tell you about the alien knowledge ray in a science fiction novel? It was a teaching primer in the form of the universal language of mathematics. Viewers would see colors on a screen. Spheres would form and intersect as an introduction to set theory which would go on to Boolean algebra and higher things. This program only made sense to people with IQ over 150. These individuals would get hooked and could not stop watching, but then their brains would implode leaving them as vegetables. It was found in the course of the novel that the program operated an “inverse neural feedback loop” that measured the person’s IQ against their emotional and moral development. Strongest effects were reserved for the largest difference between intelligence and maturity. Your average human, being relatively immature and capable of violence, merely got their brain fried. But evil geniuses were actually killed. It turns out that the alien space program was designed to suppress societies which were not emotionally equipped to handle technology and prevent them from achieving space travel where they could do damage on a much greater scale. It’s an interesting book called The Macroscope. Anyway, color visualization can help.

    Matt61

    • Wulfraed Says:

      Very well… I tried an experiment… and it worked…

      pairs(tt[,2:6], pch=c(1, 1, 1, 4, 4, 4), col=c(“red”, “red”, “red”, “red”, “red”, “red”, “green”, “green”, “green”, “green”, “green”, “green”, “blue”, “blue”, “blue”, “blue”, “blue”, “blue”))

      http://wlfraed.home.netcom.com/TwistTest.png (yes, same link, I just replaced the image file)

      What we now have is:

      o => Premier
      x => JSB Exact

      red is 1:12 twist
      green is 1:16 twist
      blue is 1:22 twist

      Unless R allows defining a background for the plot character I can’t add a differentiation for the power level… (well, I could probably rig pch to use open circle and square for one, and filled circle/square for another — but not a third).

      • Desertdweller Says:

        Knock it off, you guys!

        I just finished a lesson in my Advanced Navigation class and then I get hit with this.

        I think I feel my brain imploding!

        Les

      • Toby T. Says:

        Wulfraed, just curious, what do you do for a living? You remind me of a friend that works at Los Alamos labs.

        • Wulfraed Says:

          Software engineer… 30 years at Lockheed Martin Sunnyvale CA (then 16 months of enforced freedom before snagging a position at GE Aviation Grand Rapids MI).

          GE is a much different environment — for one thing, the software is all real-time stuff that goes into aircraft systems; Lockheed was all number crunchers where some programs would run for an hour or so, and normally would be run a day in advance (building schedules for the next day controllers to use).

          • Toby T. Says:

            Wulfraed, thanks for the response. I figured you were an engineer or someone who dealt with numbers, equations , formulas … Pretty cool. Toby

            • Wulfraed Says:

              I’m actually a bit weak on the math side. At Grand Valley, Comp. Sci. was in the math department, so all those classed in programming languages were considered “math”. I’m sure that has changed since 1980.

              Oh, I did have to suffer calculus, probability & statistics 1, and a graph theory class. I never went on for an MS degree as all the programs where I was working had pre-requisites of differential equations, and I’d have to first worm my way into a community college class just as make-up.

  • kevin Says:

    Edith & Tom,

    Just received the new Pyramyd Air catalogue. Had to comment.

    This is the best Pyramyd Air catalogue I’ve ever seen! It flows so well. The articles are so appropriate. “How to sight-in an air rifle” and especially the “Teaching kids to shoot” are perfect. Previous articles seemed to be condensed to the extreme. “Airgun powerplants” belongs in every catalogue.

    The amount of work that went into this new catalogue is readily apparent but greatly appreciated. Since I see both of your fingerprints on every page I wanted to say well done and thank you.

    I’m seeing many new names on the blog lately and expect to see even more in the coming months because of the encouragement in the catalogue to visit the blog. You’ve created and educated a large airgun community. You should be very proud of this legacy.

    kevin

    • B.B. Pelletier Says:

      Kevin,

      Thanks for your remarks. Edith puts her heart and soul into making the catalog and this one is even getting Pyramyd Air call-ins that agree with you. She is very pleased with how it turned out.

      B.B.

    • Kevin,

      Thanks for the compliments! As you can see, I took your advice and added an invitation to the blog at the end of every article. I agree that it should swell the ranks of the blog readers.

      Edith

  • Feinwerk Says:

    Thank you, B.B. Fascinating read. In the case of the M16 @ 3200 fps and a 1 in 10″ twist rate, the bullet is spinning at 230,000 rpm! That kind of rotational speed is hard to imagine. If it’s not perfectly balanced it’ll surely oscillate in flight.
    I guess you could generalize that the higher the length/diameter ratio of the bullet, the faster the twist rate should be. However, it seems to me that for airgun pellets with skirts, the higher the l/d, or, the longer the pellet for a given caliber, the more stable it is aerodynamically, perhaps requiring a slower twist rate. I think that’s why Kodiak/barracudas tend to be so accurate. They’re quite long with most of the mass forward in the head-more like a throwing dart.

  • Gunfun1 Says:

    I would like to comment about the catalog also.
    The Airgun Powerplant article was cool . It always amazes me how the different topics remind me of times past in one way or another.
    But I really liked the article about Teaching kids to shoot. My girls have been shooting for somewhere around 5 yrs. now. They read stuff on the Pyramyd blogs at times. Of course when we read the topics together. I have taught them safety over and over through out time among other things about shooting.
    But it was good for them to hear the rules from somebody else besides Dad.
    I didn’t even know the new catalog came because the oldest girl grabbed it first. She showed me the article about Teaching kids to shoot.
    And the article that caught my attention was the one that Josh U. wrote. Sometimes honesty is the best medicine.

    Again one of the more informative catalogs I have seen. Not to say the other catalogs were not good also. ;)

    • Gunfun1,

      Thank you for your comments. Like the other comments about the catalog, I passed yours along to the marketing department. It’s important that they know the articles are well-received by airgunners of all backgrounds and experiences.

      I still remember the conversation Tom and I had in November 2006 with Josh and Val (Val is now the president of Pyramyd Air): Pyramyd Air’s No. 1 mission is educating customers.

      Nothing has changed since then.

      Edith

  • Gunfun1 Says:

    Thanks Edith.
    And I believe if you keep the mindset of educating customers the people will follow. And it is a win win situation if everybody throughout the process can be informed.

    And like one of the comments after you make a order with Pyramyd Air (I might not be stating this exactly) “We appreciate your business we know you have a choice”. All I can say is I like the way the catalog and website is layed out. And I have had nothing but good results with Pyramyd Air. And that is why I buy from Pyramyd to this day.
    Thanks again.

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More and more, we're hearing that airguns are ideal for firearm training when it comes to improving trigger control, acquiring a target and increasing accuracy. While all those are big pluses, let's remember the other reasons: (1) Save a fortune on ammo (if you can even get firearm ammo!). (2) Shoot at home. (3) No hearing protection needed. (4) Airguns are a fraction of the cost of firearms. So, click on the image & add this to your gun vault.

New .22-cal. Sheridan!
Sheridan 2260MB CO2 rifle

Sheridan has always made .20-cal. airguns. So, this new .22-cal. rifle is particularly exciting. And, it's available only in limited quantities. If you collect Sheridans (or just love them for their quality), you MUST add this to your gun vault. It's a single-shot CO2 rifle with a metal breech. Bolt-action single shots like the 2260 are ideal for teaching proper gun handling. Everything you love about Sheridan guns…and more. Get yours NOW before they sell out!