Some thoughts on pellet design: Part 2

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

Part 1

Today, we’ll look at my solution to the solid pellet for a 20 foot-pound rifle.

The first thing you have to know is how much this pellet will weigh. There’s a very quick and easy way to determine this. Find the weight of a round lead ball in .22 caliber. The .22-caliber Gamo Round Ball weighs 15.43 grains. When I did my design, I actually weighed round balls and found them to weigh 15.3 grains. So, that was my staring point.

Now, mentally extend the ball into a cylinder of the same width and height dimensions. The cylinder will be flat on top and on the bottom. The extra lead will increase the weight of the cylinder to just over 20 grains. Remember, this cylinder is just as long (0.2165″) as it is wide (0.2165″).

What velocity will a 20 foot-pound rifle drive a 20-grain pellet? Go to the Pyramyd Air velocity calculator and enter the pellet weight and energy…but you don’t even need to do that, do you? Because, if the energy is the same as the pellet weight in grains, the velocity has to be the magic number — 671 f.p.s. Try it in the calculator and see. Use the second formula for your calculations.

Is this precise? Not yet, because we don’t know the exact weight of the new pellet that hasn’t yet been designed. It’s just a ballpark approximation that gets you going. But even if your finished pellet weighs 24 grains, you still know that it has to be driven above 600 f.p.s.

I said I wasn’t going to ask you for the math, but I know many of you will find that easiest to envision, so here it is.

The math
The formula for the volume of a cylinder is Π (pi) times the radius squared times the height of the cylinder. The formula for the volume of a sphere is 4/3 Π times the radius cubed. Lead weighs 0.4092 lbs. per cubic-inch.

I did the math and determined that a cylinder of lead that is 0.2165 inches tall by 0.2165 inches in diameter weighs 22.83 grains. Using the same math but a different formula, I calculated the weight of a lead sphere of 0.2165 inches diameter weighs 15.2 grains. That’s close enough to the 15.3 grains that I measured to use these data.

My estimates were not exact — they were close. Close enough to make this workable without doing the math because, at this point, what we’re doing is determining the envelope for the new pellet. Blog reader Mark was the first person to weigh in with the results. He said the pellet has to be short and fat. Bravo, Mark!

The design
I asked you to design a solid pellet for a 20 foot-pound rifle because that is the hard task. What I actually did was design two pellets — one for 20 foot-pounds and one for 60 foot-pounds. What I’m about to show you are both pellet designs. The 60 foot-pound pellet has my concept thoughts on the drawing, while the 20 foot-pound pellet has just the dimensions.


20 foot-pound solid pellet design

20 foot-pound solid pellet dimensions
As you can see, this design is lighter than the cylinder of lead described above. So, it goes faster and spins faster, thus having a greater chance of stabilization. This one probably weighs 19-20 grains.

Also note that the driving band at the rear is very thin, so loading should be easy. The body of the pellet is smaller than the smallest diameter of the target bore size of 0.2165 inches.

Notice that the band at the head doesn’t get engraved by the rifling. It rides on top of the lands. The rear band is what seals the compressed air behind this pellet. This also helps the loading.

Notice that this pellet is shorter than it is wide. It’s very stubby, which we believe to be necessary for stabilization in a lower-powered air rifle.

Will it work?
In theory, yes. But until you make some pellets and test them, you won’t know. It may work well in some guns but not in others.

60 foot-pound solid pellet design

60 foot-pound solid pellet design
The 60 foot-pound pellet is different than the 20 foot-pound pellet. The basic idea remains the same, but there are small yet important differences to work with the 3x higher power.

I gave no dimensions with the 60 foot-pound pellet because I wanted to test the 20 foot-pound pellet first. Until we knew how well it performed, the larger pellet was just a concept.

Summary
These pellets were designed to work well in the pneumatic rifles mentioned above. You’re looking at the exact design drawings that were used to get the solid pellet project underway.

My pellet was never made, but there is a similar pellet on the market that came out a year after I shared these drawings with the company. That pellet is made by a different company. It has some differences from my design; but if you look at it, you can see the similarities. That pellet is still in use today and seems to work as designed. So, I feel confident that my design would work.

This is as much of the story as I’m willing to tell.

48 thoughts on “Some thoughts on pellet design: Part 2

  1. Since the projectile is solid, and has little drag for stabilization, it seems much more like a bullet than a pellet. In the first part I didn’t understand that we were designing two pellets, but that makes sense.


  2. This is AWESOME stuff, B.B.!

    One of the things I really like about this sport is the fact that because air guns are so much less powerful than powder-burners, they require very subtle engineering and understanding to maximize their performance (which includes accuracy, of course!).

    Thanks for going to the effort to explain this.

    Dave


  3. Very interesting. The Daystate Magnum .22 caliber pellet looks very similar to your 60 foot-pound design, but they are 50% heavier than your version. The Norica Ban looks like your pellet, too. It reminds me of a .22 cal version of the old Sheridan cylindrical pellet and weighs just under 21 grains but only has a single driving band at the base. I think they are out of production now. I have a couple of tins of the Noricas but I have not had the time to test them yet.

    Paul in Liberty County



  4. Agree with Mark – JSB Exact Monster. However, that pellet is not entirely solid – the base is hollowed out a bit, which probably helps the swaging of the base into the rifling.



  5. BB

    Interesting. Seems very similar to the bullet used in some of the .22 BB/CB Cap or .22CB short loadings (which can weigh in from 15-30 grains).

    Honestly though I’m not sure I really see the point in using a bullet in an air-rifle. Especially since it means the bullet will travel roughly the same distance as a bullet from a firearm. Seems to me that for something like squirrel hunting, or any hunting really, a pellet which maxes out at around 500 yards is safer. Ditto on target shooting. There’s also the little matter of it being harder to stabilize…

    J.


    • J.,

      What you said is correct, and is the reason some people want solid pellets. They think they can get around using firearms if their airguns can do the same things.

      I’m with you. I want my airguns to remain airgun and my firearms to do the same.

      B.B.


      • BB,

        Actually I think I’d kinda like firearms ammo makers to consider taking a page from airgun ammo and offer diablo bullets (or some other relatively inexpensive, short-ranged, single-projectile option) for rimfire rounds. I’ve seen too many videos of people taking shots at squirrels in the tops of trees (some on Youtube, others on professionally done hunting shows) apparrently without much, if any, thought where the projectiles will come down. I’m usually not too concerned when I see someone doing that with a shotgun or an air-rifle, since the projectile(s) won’t go that far and should have negligible energy at the end of their trajectory. However it concerns me a bit when someone does that with a .22 rimfire since the bullet will travel much further and remain dangerous far longer…

        I’m probably over-thinking things, but it seems to me that as the population density in rural areas rises that makes using traditional rimfire ammunition for things like squirrel hunting ever more dangerous. And it doesn’t help that kids (and many adults) don’t seem to ever consider this sort of thing and as a result hunt not just in the relatively safer rural areas but in their backyards. Hence the desire for a shorter ranged, safer, rimfire option. Its also the reason that I consider air-rifles a nearly perfect choice for squirrel hunting.

        J.



          • BB,

            Thanks for the compliment on the idea. However my next question is going to seem odd, but I’m curious about how viable you think it is. So realistically how likely do you think it is that an ammo company would be interested in working up a loading?

            Just to kind of elaborate… I was thinking of a 20 grain, .223-.224 diameter, diablo pellet at 1000 fps (for right about 44 ft-lbs muzzle energy) and a maximum range of around 500 yards. For a case I was thinking either a .22LR or .22short. (I’m not sure what would work better since the .22LR would likely require some form of filler due to the case length.) Does that seem about right or at least in the same ballpark.

            J.


            • J.,

              Definitely the .22 short, or even the CB cap. The effective distance might be 50 yards, with 500 yards the max range.

              It is an intriguing idea.

              BB.


            • I’d be concerned with how you retain the pellet in the case.

              .22 rimfire cases crimp over the base of the bullet, and the portion of the bullet /outside/ the case is what is sized to engrave the rifling. In contrast, many pellets are sized to ride the lands, and rely on the /base/ expanding to engrave the rifling.

              If you crimp around the pellet nose, you have a loose fitting pellet — and the initial impulse is likely going to mash the hollow/conical base up against the nose before the pellet breaks free of the crimp. If you crimp around the base, you need a long sided pellet

              (=<==

              instead of
              (==<


              • Wulfraed,

                Why not take a page from old-fashioned (circa 1900) .22 target ammo which, if I’m remembering Sam Fadala’s book on the .22, was not crimped but held in place by friction? Or simply crimp lightly right behind the pellet nose where it starts to narrow and have the skirt be big enough to fit fairly tightly in the case which should keep it from being mashed/cause it to expand to size when fired.

                Tom,

                I was thinking that a .22 short case would probably be about right myself. And 50 yards should be more than adequate for squirrel hunting. Who knows… Maybe something like this would reawaken interest in the .22 short.

                J.


                • J.,

                  You have a good idea. But I don’t know how receptive ammunition makers would be right now, when they are running three shifts a day just to lessen their backorders?

                  B.B.


                  • BB,

                    I’m not sure either, but I bet the answer is probably not very. This sounds like something that’s going to take some tinkering. And even if it moves past the experimental phase, it would cut into production time for existing ammunition. Given the demand we’re currently seeing for ammunition and firearms, I really doubt companies would want to expend a lot of time, money, and resources on developing a new concept round, no matter how good it sounds. I think this is something that will likely go into the vault. Maybe once the crazy dies down (if it ever does) something will come of it.

                    J


  6. Well, this is certainly a different-looking pellet design. What exactly was it supposed to achieve again? I see the small remnant of the pellet skirt, and the absence of the full skirt makes me wonder what the skirt is supposed to do in ordinary designs. Doesn’t it play a major role in drag stabilization which is given up in the new design?

    Victor, you were right about the need for more aggression with the hard triggers. With my lighter triggers, I likened the trigger squeeze to sending my ship out and waiting for it to arrive. With the B30 trigger, the ship never arrives. But by enforcing the 3-6 second time limit, those pellets are dropping right in there. You just have to show the trigger who is boss.

    Speaking of triggers, I’m pleasantly surprised by the Mauser trigger. It is two-stage. The release isn’t like a glass rod, maybe more like a rod of hard rubber, but it works fine. And it is well ahead of the Mosin trigger. The rifle also is a pleasure to handle. Where the Enfield has a massive John Bull quality with its straight lines and the M1 Garand is even chunkier, the Mauser is light and jaguar-like in the hands. But with that short length and the 196 grain bullet, I’m bracing for recoil. That buttstock is also fearsome the way it is sheathed in metal; it could do some serious damage.

    I wonder if I have made a new discovery about Mauser sights. They consist of a triangular front blade and an extremely wide square notch in the rear. But looking closer, I see that in the middle of the rear notch there is a teeny tiny almost imperceptible inverted V notch that must be just millimeters in diameter. And you can get the tip of the triangular front blade to just set in the rear V. This must be for precision shooting. The big square notch is for low-light, rapid sight acquisition and the human wave attacks. The tiny precision notch also lowers the point of impact quite a bit. Could it be that the reason why most people claim that Mausers shoot way high is because they miss the small notch? Actually, I’m sure that people have noticed this notch before me. :-) But the accepted reason why the Mausers shoot high makes no sense to me either. The claim is that they were zeroed for 300 yards. That well may be as a matter of doctrine just as the battle zero of the M1s was supposed to be 200 yards. But if the elevation on the Mauser is clearly marked down to 100 yards, then the rifle had better be zeroed at 100 yards at that distance rather than 300 which wouldn’t make any sense. Can’t wait to try this out.

    I didn’t escape unscathed though with my Mauser. I see that some knucklehead reversed the second barrel band from the front with the sling loop so that I can’t mount my reproduction sling. The Germans mounted the sling on the side rather than underneath the weapon, and with the sling on the wrong side, I’ll have the bolt handle rubbing against me rather than facing away. Anyone know how to get the barrel band off? I looked around on YouTube and some guy was whacking it off with a mallet. I think I’d rather pay the gunsmith than try that on my well-preserved rifle.

    Chuckj, good thoughts on the Doo rag. But if the aim is to keep sweat out of the eyes, why not a sweatband of the kind worn by the Karate Kid or Rambo? And this would be even cooler than the Doo rag without the cloth covering the top of the head. All I can think of is that maybe the Doo rag offers better camouflage than the top of the head.

    Thanks for the info about the SW686 and cleaning. I had another concern that popped up in the wee hours. What is your take on the internal safety lock? I’ve heard complaints that they will fail or lock up every now and then. That seems a little surprising for a SW product. Also, do you suppose that the SW warranty still applies even when I’m not the original buyer?

    Matt61


    • Matt61,

      I’m glad that helped. Again, so much of shooting is mental. But the big mental demons during a long competition are internal distractions. It doesn’t take much to pull out of the 10 ring and into the 9 ring. So having 100% concentration during each shot is a big accomplishment.

      Victor


  7. B.B.,

    Thanks for the nod but I only pieced together the info you had given us in part 1. No biggie. I had trouble trying to decipher what you were after but short and fat was the ticket due to the slow velocity.

    I think the future is bright for pellet design. I think there is some rapidly developing technologies that could have a dramatic effect on pellets and our hobby. I would elaborate but I like to keep my ideas to myself.

    Thanks again,
    Mark N


  8. This has been fun so far. I took the liberty of taking the 20 ft-lb design in to 3D CAD and then peforming flow analysis on its shape at 1100fps. Anyone interested in seeing the results?


  9. Going along the pellet thing, I have to ask this. What is it with all these lead free pellets” Gamo has one labeled “lethal”. Crosman is rebranding a bunch of cheesy plastic pellets that have these metal tips that have been around many years as “new”…. I’ve actually tried all these lead free pellets in quite a few guns from old crosman air17 at 450 fps (yeah I know my past disdain for old guns but it wasn’t old when I bought it.) all the way to an airforce condor set as high as I can get it, and every one I found lacking. What is so wonderful about these that people want them? I found a nice heavy pellet is far better than an aluminum or plastic sabotted bit of metal.


    • John,

      There are a lot of people who look only at speed. Accuracy doesn’t seem to be a big deal. That’s why many mfrs are going for the fastest velocities they can publish. When you have a customer who is willing to pay for speed alone, everyone rushes to cash in on fast guns.

      Maybe those shooters will some day be interested in accuracy. From what I’ve heard/seen at gun ranges, where guys often miss targets completely (at any distance), it appears that many shooters assume that all guns aren’t going to be accurate.

      Edith


      • Ah well. I guess we have to deal with people that don’t understand hitting the target is main idea behind unleashing a bullet or pellet. I investigated these non-lead thing because there was something going around Michigan’s congress about banning lead in sporting supplies such as fishing tackle and ammunition. Environmentalists for some reason got a case of rabies here about lead, so as a preemptive thing I investigated non-lead ammo. The lead ban died off without ever getting a vote in Lansing so i dropped the idea of looking at non-lead pellets. The idea lost all credibility with me the time I tried to use a crosman non-lead hollowpoint for hunting a rather raggedy old groundhog I was tasked with getting rid of. I had him lined up in my sights, 10 feet away for a perfect heart shot. At that range I should have easily killed him, and i would have with any lead pellet. To double my chances I recruited a friend and we set him up in a nice military style crossfire pattern. Both guns went off at nearly the same time with both guns lined up on him for a perfect kill. Both guns made a nice loud sonic CRACK and we missed him as both non lead pellets went off to unknown locations. I think I nicked an ear but we did not kill the groundhog. But to be fair this thing has dodged .410 slugs, 20 guage buckshot, 12 guage buckshot, .22 rimfire, and just about everything else I could throw at him. I finally got tired of messing with this thing, and got tired of what i’m convinced was either a very lucky beast or an undead beast and set a connibear trap over his hole. Not very sporting but I finally got him after casing him around for 3 years and many, many gray hairs.


        • Close counts in horseshoes and barking a squirrel. If you actually hit a squirrel with a 0.50 cal round there wouldn’t be much to eat. :-)


          • Not so. Done it plenty of times. Head shots up close, one to the back of the ribs at some distance.
            The worst I ever messed one up was a close end to end shot with a .36. Very hard to clean…or should say to skin.

            twotalon


            • For small things like squirrels I find my condor with a .22 24 inch barrel and aftermarket barrel shroud to keep me good and quiet is all I need for squirrel. My biggest problem with those is they all seem to have perscription grade A.D.H.D. and have been overdosing on red bull.


              • john…

                I will plug a tree rat (fox squirrel) with almost anything, if I want to eat it. Then there are the little reds…they die anyway. Biggest thing I ever shot at a red (solid slug) was a .577 in excess of 500 grains. I missed, but never saw a tree rat move so fast.

                twotalon


                • I have to be quiet about it. Most of the time I’m taking out the squirrels around my deer blind so I want to make as little noise as possible or I’m dealing with a squirrel using my livingroom screen for a lader to get to the apartment above mine. The things do a real number on window screens so I’ll hazard a .177 hole to drop one before I need to replace the screen. Basically I hunt squirrels to increase my chances for a deer which I like much better than squirrel.


                  • john..
                    I like bambi too. I have nailed tree rats with my bow when they got too close. Ground shots only. I get my arrow back !
                    Bait those rats if you want to. Sunflower seeds work good. A guy I knew told me that granola really sucks them in. Like mice to peanut butter.
                    I got one with granola one time less than a block from the Dairy Queen in south Omaha with a Crosman pistol (MK 1 ?).

                    twotalon


                    • Most of the time I’m simply picking them off when they get to scattering my deer bait. I start baiting the area I want the deer to be in late summer with corn or carrots. The squirrels will scatter my bait making a mess and making my bait area less effective. I take great pains all year long working to get that deer even washing all my clothes with scent killing soaps and using scent killing soaps when I’m taking baths so I don’t have any describable scent come deer season in case the wind is not in my favor. If anything I seem to always smell slightly of apples. I work on my gun constantly as well loading my own rounds, balancing the slugs, making sure my sights are dead on….Yeah, I take it all very seriously. As a result I fill my freezer every year, as well as several family members and donate any excess to local food banks.


          • So very true. Since I never miss at 10 feet and plenty of time to line up the shot I’m fairly sure it was the pellet flying wide right out of the barrel since the gun used at the time I know was accurate. I’ve upgraded my equipment quite a bit since then going from springer to better springer to pcp to best pcp I could find then setting it up to suit my needs. I just added 2 new guns to my arsenal this week. Both powder burners for those times that a nice powerful pellet hit just doesn’t send enough love downrange. This year there will not be such a thing as a lucky groundhog.


            • John…
              The thread was getting pretty thin.
              I have known people who hunt just to hunt, then give the meat away or sell it. Other than varmints and vermin, I shoot it to eat it.
              I was surprised that my wife likes my cooking with deer and squirrel. She found out that once you get the skin off, it’s just a piece of meat. No longer a cute animal.

              She loves squirrel with gravy and busqits. And deer ribs. I usually ate the steaks, but she likes them too. Just not quite as much.

              Glad you share. Not just to make a profit selling or to get a rack to hang on the wall.

              twotalon


              • I found that both types of H&N Green (lead free) pellets work very well in the guns I use. I only do indoor target shooting with sub 500FPS guns at 10 meters max and they group nearly as well as H&N Match (lead) pellets. I decided to try them SPECIFICALLY because H&N does not sell them with claims of extremely high velocity or trying to make out that they’ll make your airgun more lethal than an 88mm FLAK gun. They just claim that they are good pellets that happen to not be made of lead. My most used “range” is just my games room with the door closed and a silent pellet trap at one end. I decided I would rather avoid the possibility of leaving any lead particles or dust in a room where kids and pets roam much of the time. If the Greens hadn’t worked I would probably do all my shooting in the alternative crawlspace “range” using pure lead pellets.


  10. BB,
    One useful piece of information: Lead is about 2860 grains/cubic inch. Saves running the converter, just multiply volume in cubic inches by 2860 to get weight in grains.

    This page is also pretty interesting:
    http://www.tmtpages.com/twistrate.htm

    My first reaction to your design is that it is going to be biased toward weight in the rear (CG behind geometric center), I think. Combined with the blunt tip and resultant high drag (both frontally and from the side), it may be a little squirrelly and perhaps prone to tumble. I think a hollow base would benefit it significantly, combined with rounding the tip more.

    I think my design will go to all lead for the 60fpe rifles, probably about .28″ long and mid to high twenties in weight; probably would work for somewhat lower power as well. For a partial (caricatured) visualization, look up “Knoxville sunsphere” :). The driving band at the base is just a rounded spherical section. A hollow base is not necessary, but I think it might be beneficial in several ways.


  11. I have a box of tin alloy 7.95 gr Sn1 Dynamic Air Bullets in front of me. They look similar to your design. They work well out of my HW98.



      • My HW98 is a springer. It is not a pellet fussy airgun. I like lead H&N FTT 4.51 mm pellets from Pyramyd, usually. But I was curious about non-lead pellets. Either the Baracuda Greens or the Dynamic pellets are very accurate. I like the Sn1′s because they weigh about the same as CPLs. The downside of these pellets is they are too expensive, 2-3x cost of lead pellets.


  12. BB,I think your first design looks like a rabbit magnum 2, but those and the others mentioned all seem to be a little too long by comparison.-I like your second design even better.The middle band is such a great idea;I wish I’d thought of that.You would think you wouldn’t need that with the head fitting so closely.But if I understand it correctly most all projectiles start out with a wobble and thin correct themselves downrange.This would minimise wobble from the start and ensure a correct heading.I would like to try some in my Evanix AR6 rifle.It produces 58fpe and some change right out of the box.–I’m sorry to hear about the way you were treated.It is sad the way people steal from each other.If they had stolen a rifle it would be gone ,but this is a theft that they just keep on stealing with every sale.A man can’t be any bigger than when he turns around and promotes a companies products even in the face of that.You seem to promote them all according to the product’s merits.Before you head out drinkin’ think of the legacy you are building.You have readers all over the would.We here on this blog know a little of your worth.You are worth so much to us.Your legacy is something NO ONE CAN EVER TAKE AWAY!


  13. Would a pellet made of graphite work? We were talking about lubing ast week and graphite was mentionned and if enough pressure is put on it it’s solid enough (they make high hp engine blocks with graphite) or is it two different forms of graphite? Would the weight be sufficient? I know they make engine blocks with it in order to reduce weight so…

    J-F


  14. Shooting a bone stock Hatsan 125 in 177 cal, finding a pellet that could work with the power was interesting. Anything below 10 grains went SS, and anything above 13 lost energy. None out of several were at all accurate.

    Came across come Air Arms heavies in cylinder shape weighing I believe 10.5 grains, and it was like magic. The design was much like these in this post, only not solid. Basically a cylinder with a small ridged dome and a minimal skirt, but with a longer body. The Hatsan sent these pellets at an average of 1050fps for 25 fpe, and accuracy was phenomenal. I produced several 1/2″ groups at 45 yards, which is nothing short of excellent, particularly out of a beastly 125 with no tuning.

    Since the Air Arms are just rebranded JSB’s, had hoped to get more of these, but suddenly they no longer appear anywhere. The heavier JSB’s are similar, but with a more waisted design, and shot horribly, and the Air Arms cannot be found. So I sold the gun rather than tune it to a particular pellet.

    I fully believe it was the cylindrical shape responsible for the transformation.At high speeds over 900 fps, the moderately long cylinder with a nose heavy bias just seems to produce more stability. Would like to see some pellet makers explore the design more thoroughly, thats for sure.


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