**Test Results** Forward Velocity vs Bullet RPM

[PigButtons]

I think you just created a new unit...Detector Transits / Second.

I will expect a citation when published!

A much, much easier way is to take the distance in between detectors and divide by the barrel twist. 2/8 = 0.25 rotations per detector

Yea, but mine sounds more like, " A train leaves Chicago heading West at 65 mph..."

You must have used a 1:6 twist barrel in your test.

Not exactly. That was from the rounding errors that I introduced.

A Varmint bullet doesn’t drill holes...it explodes!

Yes, but just like when two galaxies collide, that rotational energy continues to affect the final distribution of matter.

 

[AllThingsAI]

Wasn't really trying to show or prove anything.. Was just giving some (probably useless) information..
With regards to your formula about the "C"ircumference ( or distance around the bullet)
C=2xPixR or C=Pi x D Same result...
I always thought a 223 was .224" in diameter...
All is was showing was the total rotational distance the bullet traveled during its flight.. Again useless information..
Not wanting to start a battle about your calculations or work on this.. so, I wish you luck and success in your efforts..[/

Wasn't really trying to show or prove anything.. Was just giving some (probably useless) information..
With regards to your formula about the "C"ircumference ( or distance around the bullet)
C=2xPixR or C=Pi x D Same result...
I always thought a 223 was .224" in diameter...
All is was showing was the total rotational distance the bullet traveled during its flight.. Again useless information..
Not wanting to start a battle about your calculations or work on this.. so, I wish you luck and success in your efforts..

No worries, I just didn’t understand what you were trying to show with the math, and yes you are correct that D*3.14 is the same as 2*R*3.14. ...I was just writing faster than my brain processed what I was reading. No worries at all, I was just trying to understand your math. What I thought about last night and what was interesting is you calculated the distance the bullet would roll if it went completely sideways like a tire....actually pretty interesting! Keep jumping in, I wasn’t trying to be rude.

 

[AllThingsAI]

I will expect a citation when published!


Yea, but mine sounds more like, " A train leaves Chicago heading West at 65 mph..."


Not exactly. That was from the rounding errors that I introduced.



Yes, but just like when two galaxies collide, that rotational energy continues to affect the final distribution of matter.

Too funny! Love the last one!

 

[357Mag]

AllthingsAI -

Howdy -

A quote from reknowned ballistician Homer Powley, that I gleaned from his " Powley Papers " article; as it appeared in the
" Guns & Ammo 1974 Annual " .....

" If you shoot into something plastic which will stop the bullet, such as soap, mud or metal, you will find that the size of the cavity is proportional to the remaining energy. If the bullet breaks up rapidly, the cavity will open, and close to the entering surface. If it holds together for a ways, the cavity will be long and narrow. That is to say, cavitation is proportional to the energy. High speed photographs show this to be the same in liquids, semi-liquids; and animal tissues ".

I DK if this helps any ?


With regards,
357Mag

 

[AllThingsAI]

AllthingsAI -

Howdy -

A quote from reknowned ballistician Homer Powley, that I gleaned from his " Powley Papers " article; as it appeared in the
" Guns & Ammo 1974 Annual " .....

" If you shoot into something plastic which will stop the bullet, such as soap, mud or metal, you will find that the size of the cavity is proportional to the remaining energy. If the bullet breaks up rapidly, the cavity will open, and close to the entering surface. If it holds together for a ways, the cavity will be long and narrow. That is to say, cavitation is proportional to the energy. High speed photographs show this to be the same in liquids, semi-liquids; and animal tissues ".

I DK if this helps any ?


With regards,
357Mag

Sounds logical to me!

 

[Webster]

Sounds logical to me!

There was an Army sniper interviewed on TV. He thought that a 308 round that hit at longer distance might do more damage because it was in the body longer. I’m sure it was personal opinion. He didn’t do autopsies.

 

[XTR]

I'm pretty sure a good portion of what you're seeing in the paper, at least in the first layers, is spalling from the aluminum plate. I think you might try something not metallic for your first layer. The jello in a bag idea might be a good one. I've seen similar results from spalling in a Bradley Fighting Vehicles, M1 Abams, and a few target stands at APG, when they were hit with a DU penetrator from 120mm smooth bore. (I was the Radiation Safety Officer for the facility that got back all the friendly fire hits from Desert Storm in '91.)

The other option would be to shoot a block of ballistic jell and see what happens in there. Esp. if you can get some high speed video. The bullet breakup in jell is pretty easy to see from the tests I've seen

 

[slancey]

What ever came of this study?

 

[AllThingsAI]

What ever came of this study?

Took a pause to do some other stuff, I got a bit burned out. It’s cooled off now here in AZ so I can and will get back to the range soon. i posted the results after shooting aluminum....need to track using another expansion media.

 

[slancey]

I'm really interested in this discussion. There was a video recently posted on Varminter TV of some rock chuck hunting using the new 69 grain Sierra Blitzking in a 22 Creedmoor. The results were spectacular - more so than I was expecting since velocity would be slower than the light bullets and the twist rate on the 22 Creedmoor is 1:8. It got me wondering about this twist vs. velocity discussion. Your work should shed some light on the subject.

 

[Tommie]

This excellent experiment brings to mind the chapter in PO Ackley’s book where feral burros are being culled with a .220 Swift. I’d suspect more contrasting results in various twist rates would be found at lower velocity. Either reduced loads or extending the target distance.

 

[markT]

This is a 40 gr Vmax in cast iron at about 75 yds.

 

[troupe]

Roy Weatherby proved many, many years ago that velocity kills. I have switched to 125 gr ballistic tips in my 308. 3035 fps out of my 18" AR. I can also say that velocity can work against you if you do not match the bullets accordingly. I shot a heavy whitetail years ago when Layne Simpson came out with the 7 STW. I was fortunate because I shot USPSA with Layne. I found out that the 140 Ballistic Tip was very accurate and fast. It worked great at distance, but I can say with confidence that a 7mm 140 gr Ballistic Tip at 3560 fps at 18 yards on a big deer shoulder will not kill a deer instantly. A second shot was needed and the shoulder that I hit looked as if dynamite was placed in the deer. The bullet never entered the rib cage after the deer was cleaned.

 

[AckleymanII]

I would think that shooting at 5 gallon water jugs using a slow motion camera would reveal much in how the fragments penetrated and rotated with the spin, a water proof camera of course!

 

[AllThingsAI]

I’m back! New testing to follow after some time off. Sorry for the delays. Stay tuned!

 

[john 800]

Interesting discussion here.
Ill add my 2cents... the difference may be more discernible when shot through an initial media that is on the light side of enough to initiate expansion. And with the lighter v max bullets i think you will be suprised at how little it takes to make them explode.
The experiment reminds me of something i saw years ago. I went to the range to plink with a coworker after work, partway through the day we realized nether of us had brought a target stand of any kind and the range di not provide them. So what do two auto mechanics have laying around that willwprk for targets? Empty antifreeze jugs. Taped targets to them, put sand in the bottom so they didnt tip over amd we were set. I was shooting my 14 twist 22-250 with 53 grain vmax factory ammo and i was suprised to see that after traveling only through paper an dthin plastic that there was no bullethole out the back side of the antifreeze jug, just a pattern with a bunch of small holes from fragments. That makes me wonder a few things about bullet expansion