Bullet Stability Logic

[@MattWaller04]

Mark’s understanding of projectile physics is truly remarkable. Thanks for making these concepts easily digestible.

[@markandsamafterwork]

Cheers Matt, thanks Man

[@jeanmorin3247]

This has got to be the most explicit teaching available on the Internet on this subject. Very, very good! Thank you!

[@markandsamafterwork]

Cheers Jean, thanks

[@geordiegeorge9041]

A couple of years ago I was at a match shooting 223 out to 300 meters. An 80 year old contestant asked me what bullets I was using, I told him Hornady .224 52GR BTHP. His comment was, they are too light for the weather conditions, (it was hot and there was a mirage) he told me that I would get vertical stringing, he was right.

[@markandsamafterwork]

OK, not about stability, lots about BC on that one, Cheers

[@glennllewellyn7369]

Happened to me on Saturday last. Mirage, light bullets and following wind at 400 with a 223. Zero wind(nice day). Vertices everywhere! Everybody laughed.

[@opsoverseas]

Congratulations Mark, you've rendered a difficult topic into its component physics with the fewest clearest words, well done!

[@markandsamafterwork]

Thanks Man

[@racecitypatriot66]

Best video I've seen about this subject. Thanks for sharing this info.

[@markandsamafterwork]

Cheers

[@nickerdal9425]

Brilliant explanation. Thanks very much Mark.

[@markandsamafterwork]

Thanks Nick

[@faniebasson4717]

thnx for explaining a big problem in a simple way

[@markandsamafterwork]

Cheers Fanie

[@Dwayne7834]

Excellent and informative as always. Thanks Mark .

[@markandsamafterwork]

Thanks Dwayne

[@tonydique4554]

Mark, that’s fascinating and a great, easy to understand explanation. Never seen “transonic zone” addressed like that. Thanks!

[@markandsamafterwork]

Cheers Tiny, thanks man

[@geoffkeeler5106]

Great stuff Mark, I love the technical aspects of the art. Thanks!

[@markandsamafterwork]

Cheers Geoff

[@stephenarmstrong7354]

Hyper-Stabilized Rifle bullets by James A Boatright. (and some of his other papers). If all goes well this fall I hope to be testing some Warner Tools Flatline bullets, 198 gr with and without the Tubb ring, in a custom 300 Win Mag, 33" PacNor barrel, 1 in 6 twist, 3 lands and grooves. I would also like to try Erik Cortina's dimple in the base of the bullet, but one thing at a time. Thank you for the videos, even after 7 decades, I enjoy learning something new.

[@markandsamafterwork]

Thanks Stephen, Cheers Man

[@collinmckamy8076]

Always excellent videos. I learn something every time. Thank you

[@markandsamafterwork]

Thanks Collin, Cheers

[@nolson2804]

Great explanation. Different tools for different applications. Not better. Not worse. Just a keen understanding of the various nuances and related aspects of the subject. Bravo Mark.

[@markandsamafterwork]

Cheers Man, thanks

[@wasntmeXYZ]

Very good information! Thanks

[@markandsamafterwork]

Thanks Man

[@judelarkin2883]

Thank you for another great video.

[@markandsamafterwork]

Cheers Jude

[@chrisweatherford3456]

Best explanation I've found of bullet stability & transonic effects.

[@markandsamafterwork]

Thanks Chris

[@damienmilk3025]

Great information, as always. Thanks.

[@markandsamafterwork]

Cheers Damien

[@peterstankovic1978]

Nicely explained, thank you!

[@markandsamafterwork]

Cheers Peter

[@stephanematis]

Best explanation of the details. Thank you sir, this will be a video I'll share with friends who understand physics and love to understand better what is going on with bullets. The back end wanting to go forward is something we actually discussed before.

[@markandsamafterwork]

Cheers Man

[@paulharding1621]

Fabulous explanation.

[@markandsamafterwork]

Cheers Paul

[@naylorinnovationsllc7483]

Very educational as always, thank you.

[@markandsamafterwork]

Cheers

[@JohnRoberts71]

Great content thanks for sharing

[@markandsamafterwork]

Cheers

[@bsmith8943]

Great video explaining this. The science behind this is so interesting.

[@markandsamafterwork]

Cheers Man

[@benmclean2291]

Very informative. Thanks Mark 👍

[@markandsamafterwork]

Thanks Ben

[@malcolmlittle3725]

Thank you so much for the great information. Really enjoy your channel and your incredible marksmanship.

[@markandsamafterwork]

Thanks Malcom

[@qingyuhu]

Awesome information as usual

[@markandsamafterwork]

Thanks Man

[@paulsimmons5726]

As always, great stuff!

[@markandsamafterwork]

Thanks Paul

[@lz3572]

Great content.👍👍 A great comparison is the 244 Remington 1in12 twist and a 26 in barrel the 6mm Remington. 1in9 twist and a 24 in barrel Remington changed so it could stabilize the new spitzer bullets . Keep up with the great information.👍👍

[@markandsamafterwork]

Thanks Man

[@glennmiller4607]

Really enjoyed this video, very informative 👍

[@markandsamafterwork]

Thanks Glenn

[@thomandstacieverroad8417]

You make it easy to understand. Great job once again.

[@markandsamafterwork]

Thanks Thom

[@cjzermiani]

Um exemplo excelente tem a natureza, uma 💧 melhor dinâmica!

[@markandsamafterwork]

Yes, agreed, Cheers

[@jtcustomknives]

My browning highwall in 45-70 has won competitions at 1,600 yards with its 1 in 18 twist barrel with paper patched lead bullets and black powder. It’s amazing what older technology can accomplish when you really get down to brass tacks and nitpick every detail.

[@markandsamafterwork]

Awesome, thanks JT, Cheers

[@judodavid1]

Thank you for the knowledge

[@markandsamafterwork]

Cheers

[@daveshepherd7133]

I have a Howa .308 24in 1/10 using 155gn and have shot out to 900 no probs. We have electronic targets at the club so they haven't reached the transonic zone yet. I'll be shooting 1000 in a few weeks so I'll know then.

[@markandsamafterwork]

Cheers Dave

[@keithj30]

A very interesting topic , good explanation

[@markandsamafterwork]

Thanks Keith. Cheers

[@tshepomaruping4778]

Excellent information. Thank you!

[@markandsamafterwork]

Cheers

[@Hati321]

Thanks for the explanation. What do you make of the 8.6 blackout's 1 in 3 twist?

[@markandsamafterwork]

All about achieving the RPM needed, Cheers

[@randomidiot8142]

If you do some reading on .338 spectre, .338 whisper, .338 br, .338x47, 338 federal, most of them were built on 1:6 barrels that predated the 8.6 blackout. 1:3 is excessive and reduces the supersonic capabilities and projectile choices while not significantly increasing subsonic capabilities.

[@rhekman]

Interesting topic Mark. You already brought it up with the dart, but I couldn't help but think it's a related aerodynamic problem to rockets or aircraft. To be stable, they also need their center of lift to be behind their center of mass (or CG).

[@markandsamafterwork]

Cheers

[@The_Conspiracy_Analyst]

Fantastic presentation

[@markandsamafterwork]

Thanks Man

[@jtcustomknives]

You had me when you said center of pressure and I knew you knew what you were talking about.

[@markandsamafterwork]

Cheers Man, thanks

[@todds4101]

Another great video, Mark. Apologies I haven't had a chance to watch and comment for quite a while. Trying to keep up with......everything. Really enjoyed your bullet stability video. I always tried to explain it by talking about a perfectly thrown spriral from a seasoned quarterback, but these were great. Hope all is well? Be safe!!

[@markandsamafterwork]

Thanks Todd, glad you liked, Cheers

[@walt5797]

I've often wondered if projectiles can be made with weight foreword of centre. by making the back less heavy.

[@markandsamafterwork]

That would lower the weight v area, lower BC..... Cheers

[@madman432000]

So bullets with lead in the nose area and copper in the rear would be more stable possibly, while keeping the twist rate not so fast. So we could be shooting those 131g 0.257 bullets in a 1:10 twist barrels if the bullets were made correctly. My worse encounter was with the Barnes 168g LRX in 7mm with a 1:9.25 twist barrel. they hit the target sideways at 100yds. They have a recommended twist of 1:8, but even when we tried them in a 1:8 twist barrel they still weren't stable. I suspect that rifle doesn't have a 1:8 twist barrel even though Browning says it does.

[@markandsamafterwork]

Thanks man

[@chrisgabbert658]

👍😊 compromise so a 1:11 22” barrel 308 is that. It’s good with the 168 bthp and trash with 150ish fmj .

[@markandsamafterwork]

Cheers Chris

[@randomidiot8142]

150 fmjs are usually trash to begin with. Trash in, trash out. Shoot better bullets and suddenly the lighter weight isn't an issue.

[@torontoknightking2391]

My .300 win mag has a 26 inch barrel with a 1:10 twist rate. Fairly standard I think, but am really not sure. It's really hard to understand what happens at extreme ranges, as we can't see much. Lots of trial and error to get things dialed in. It would be interesting to capture a bullet in a ballistic gel block out past a mile or so, and see what the impact looks like. Would be a hell of a shot that's for sure! Thanks for sharing, cheers!

[@markandsamafterwork]

Cheers

[@billhendon1017]

Thanks for the info!!

[@markandsamafterwork]

Cheers Bill

[@jasyamaha]

Great explanation, thank you. I've built carbon fiber rockets from 1" diameter up that break the sound barrier. The centre of pressure vs centre of gravity is what makes them stable, if you get it right. So I understand your expectations. Yesterday I brought a Howa 22-250 and was a bit perplexed as to why their 223 has a 1 in 8" twist vs the 22-250's 1 in 12" twist. Does anyone have an explanation for these choices of twist rate?

[@markandsamafterwork]

Would suggest a bit of reading there J, 223's also come in 1in12 twist, all about what the rifles are set up for doing, factory 22-250's and off the shelf ammo are set up for varmint hunting, shooting light projectiles, Cheers

[@Koelkop]

The 223 is slower, 1:8 likes heavier bullets like 60gr in 223. The 22-250 is a screamer, lighter bullets around 50gr going really fast needs a slower twist rate aka 1-12.

[@jasyamaha]

Thanks guys. My guess was the relative velocities of each but it was just that, a guess. Thanks for clearing that up.

[@stephendwyer4659]

What a dream .224 set up. 22/250 running 75s or 80s over 3000fps would be awesome.

[@sorryociffer]

Are there any good computer programs to design and test bullet profiles?

[@markandsamafterwork]

No doubt the manufactures have engineering software, not something I've used, Cheers

[@mikekeen9710]

ahhr yes understanding more now cheers. ok thinking out loud why not drill a micro bit out from the rear of the projectile to shift center of gravity forward a little as such.

[@markandsamafterwork]

That would lower the weight v area, lower BC..... Cheers

[@mikekeen9710]

@@markandsamafterwork cheers i see wot ya mean when ya say that.and on that i learn come understand alittle more cheers again. from nz :-)

[@shovelhead2155]

You can think of foster style shotgun slug as a shuttlecock of lead. Heavy in the front and a hollow base keeps a nose forward orientation without spin.

[@markandsamafterwork]

Yep, Cheers

[@billbonnington7916]

I had no idea a bullet had that many revs on it.

[@markandsamafterwork]

Yep, Cheers Bill

[@gadgethunter5732]

Have you ever tried the 240 grain Woodleigh bullet in a 1 in 10 twist 30-06? Kind of wondering if it would stabilize.

[@markandsamafterwork]

No, but designed for the job, not big on BC but center of balance works, Cheers

[@monzahunter]

Thanks Mark, Have you tried 230gr A max bullets in a 10 twist 300wm by any chance? I am just starting to work them up and they seem fine at 100 yards, 2834fps. Am I wasting my time trying to take them to a mile? Hornady says 9 twist minimum

[@markandsamafterwork]

No sorry, would have test, Cheers

[@imeprezime1285]

I think the "transonic zone problem" is rarely a problem and people seem to confuse it with stability problem some bullets experience in "subsonic zone" (jaw of repose increases- drag increases etc). Strange, but even zero jaw drag coefficient of many flat base SP riffle bullets isn't less than typical 9 mm FMJ bullet in subsonic zone...

[@markandsamafterwork]

Can be part of it, but, all explained in this and other video we have on the subject, Cheers

[@gregorynewman4993]

Hi Mark. Just wondering if you've see Eric Cortina's video where he chucks his bullets in a lathe and bores a hole in the back with a centering bit. I'm not sure if it's a piss take or whatever but if it legitimate and doesn't cause other issues maybe you could try it to help balance those sgk's. Just a thought.

[@markandsamafterwork]

This is not a problem that needs fixing, just pointing out why we need spin and what some projectiles struggle with, most don't, so don't fix what ain't broke, lol, Cheers

[@cortilach]

Gday Mark and Sam. Another very informative upload. Do you think barrel length plays in to stability and developing an effective RPM as well? I have a nice tikka 223rem that can shoot 1/4” groups at a 100m with lighter projectiles -50gr and 53gr hornady vmax. I have been struggling to get an effective load for the heavier 75gr hornady ELD match however. Groups at a 100m have been terrible. 2.5”! But still seems to be cutting clean round holes in paper. The rifle is a 1 in 8 twist (checked) and is 22.4” barrel length. I’d love to get this load to work for some long range target shooting (600 - 800m). Cheers 😊

[@markandsamafterwork]

Thanks and no, length does not change bullet stability, the twist and MV are all what matter there, sounds like other things going on there, barrel crown, shooter form and rifle set up would be the place to start, Cheers

[@stephendwyer4659]

I've got the same rifle and had similar issues finding a 75 grain load. Got there with Hornady 75HPBT running at 2760 and AR2208. Getting 1/2" at 200 yards now and can shoot out to 800 yards no worries. Flick us a message if you want to talk about my experiences getting there.

[@robertdees6393]

Mark, by my math, a bullet travelling 3,200 fps with a 1 in 7 twist rate will leave the barrel at 27,428 rpm's. Apologies to nitpick, and extra apologies if I am in error. I love what you do and how you present it. Respect.

[@markandsamafterwork]

3200 (feet per second) x 1.7142857 (rotations per foot) x 60 (secs in a minute) = 329142 rpm

[@mikecollins8241]

So, the ultimate long range bullet would have a copper jacket, and the front "half" of the core made of lead. with the rear part made of aluminum... maybe someone will make them someday :)

[@markandsamafterwork]

No, that would lose weight per area, lower the BC so less efficient, Cheers

[@ryanbudney3356]

Why don't people make bullets with a long tail, i.e. shaped more like a teardrop?

[@markandsamafterwork]

Maybe watch the video, all explained, Cheers

[@elendal]

The stability of a bullet in flight is determined by its angular velocity and the moment of inertia around its longitudinal axis. Angular velocity is the rate of change of angular displacement, and moment of inertia is a measure of an object's resistance to rotational motion. When a bullet is fired, the rifling inside the barrel imparts an angular velocity to it, which affects its stability in flight. The angular velocity of a bullet is proportional to the rifling twist rate and the muzzle velocity of the projectile. Specifically, the angular velocity is given by: w = 2πNT/V where w is the angular velocity, N is the rifling twist rate (in revolutions per unit of length), T is the time the bullet spends in the barrel, and V is the muzzle velocity of the projectile. The moment of inertia of a bullet is determined by its mass distribution and shape. The moment of inertia around the longitudinal axis of the bullet is given by: I = (1/12)M(L^2 + D^2) where I is the moment of inertia, M is the mass of the bullet, L is the length of the bullet, and D is the diameter of the bullet. The stability of a bullet is determined by the product of its angular velocity and moment of inertia, known as the spin-stabilization factor. The spin-stabilization factor is given by: S = wI When the spin-stabilization factor is high, the bullet is more stable in flight and less likely to deviate from its intended path. However, as I mentioned earlier, there is a point of diminishing returns where additional rotational energy doesn't significantly enhance stability and can introduce aerodynamic instabilities. So, in summary, the stability of a bullet in flight is determined by its angular velocity and moment of inertia around its longitudinal axis. The optimal angular velocity for a particular projectile is determined by the rifling twist rate and muzzle velocity, while the moment of inertia is determined by the mass distribution and shape of the bullet. The stability of the bullet is then determined by the product of the angular velocity and moment of inertia, known as the spin-stabilization factor.

[@markandsamafterwork]

🤦‍♂️ Cheers

[@elendal]

@@markandsamafterwork cheers ;-)

[@davidhandyman7571]

Mark, you are using logic again. That is not acceptable in this twisted world. Be careful, mate, you might get "cancelled", but not by me.

[@markandsamafterwork]

Lol, Cheers Dave, thanks man

[@imeprezime1285]

Too much spin isn't really a problem as long as bullet doesn't get deformed

[@markandsamafterwork]

Cheers

[@kuronyan3006Ackley]

✌️👍‼️

[@markandsamafterwork]

👍👍

[@airgunslugslingers]

👍👍👍👍

[@markandsamafterwork]

😊👍👍

[@solidname7839]

i think this was what the internet was invented for/

[@markandsamafterwork]

Lol, Cheers