KIlling/Stopping Power From Twist Rate??

rockinbbar

rockinbbar

New member
OK, I was one to argue that twist rate does little to add to the stopping power of the bullet you are using.

My basis of foundation was that terminal expansion & shock was attributed to your bullet design way more than the twist rate.

However, here lately, there have been more people talking about how a fast twist rate will add to the killing power of your bullet... /ubbthreads/images/graemlins/confused1.gif

I'm talking a comparison of identical bullets at identical muzzel velocities.

What is your experience?

How do you support your experience?

I'm shooting 9 twisters right now. .223 caliber.
I know they make 7&8 twisters...

I shoot mid weight 55 grainers. To me, I don't want to lose the MV to a heavier bullet. If I want a heavier bullet, I'll grab my .243 Win.

The "over stabilized" bullet comes to mind as well. Is it really possible to "overstabilize" a bullet? If not, why do they still make the 11 or 12's?

Thanks!
 
A faster twist rate can permit you to shooter heavier (longer) bullets, which in turn generally leads to more ft/lbs of energy on target. (Though velocity also plays a large part here). But I can't see how the rate at which your bullet spins in flight can, in of itself, result in more "killing power".

And you can, of course, over stabilize, resulting in too much spin to a bullet that's too lightly constructed to withstand it. It may come apart in flight, well short of its target. Generally harder to do than under stabilize.
 
AS far as i know (im no expert) but the twist rate is totally for stability. I think either a bullet is stable or it isnt. How long it holds stability, depends on a number of things. For the general rule that ive seen on here, the higher twist rates for the longer/heavier bullets, and the lighter the bullets dont require as much twist, it can hurt stability (reaching here) if the lighter bullets are fast enough out shoot the rifling,(if that makes sense). Many guns like 223 find a medium like a 1-9 to shoot a variety of weights/lengths. You will see , speeders like the 22-250 generally have a much slower rate cuz all the loads are pretty hot. IM sure every bullet or load has its optimum twist rate. But since we cannot change the rate, instead we work up loads that shoot good in that particular gun, which a big part of is matching the bullet to twist rate. IM sure someone with more knowledge can elaborate more but , i should be in the ball park (i would hope)
 
Okay, here's where I get off the bus. I have read thousands of words and notes from the experts. Could I possibly give the correct answer....probably not, but I can let you read some of what I have.

http://www.riflebarrels.com/articles/bullets_ballastics/bullet_imbalance_twist.htm

I have a few AR's that have different twist rates(but there is no possible way to get equal velocities from each of them for an experiment-although it sounds like fun), and different chamber dimensions.
If I fire the same load through all the AR's at water jugs, I see more explosive hits with the quicker twists. But the test can't be completely accurate due to the differences in velocity(always something to ruin a fun day at the range).

Scott (doubt this helped) B
 
Scott it is helpful. It's practical experience...That's what I'm after.

I think Jack Roberts knows more about this...Perhaps he will post as well.
 
Quote:
OK, I was one to argue that twist rate does little to add to the stopping power of the bullet you are using.

My basis of foundation was that terminal expansion & shock was attributed to your bullet design way more than the twist rate.

However, here lately, there have been more people talking about how a fast twist rate will add to the killing power of your bullet... /ubbthreads/images/graemlins/confused1.gif

I'm talking a comparison of identical bullets at identical muzzel velocities.

What is your experience?

How do you support your experience?

I'm shooting 9 twisters right now. .223 caliber.
I know they make 7&8 twisters...

I shoot mid weight 55 grainers. To me, I don't want to lose the MV to a heavier bullet. If I want a heavier bullet, I'll grab my .243 Win.

The "over stabilized" bullet comes to mind as well. Is it really possible to "overstabilize" a bullet? If not, why do they still make the 11 or 12's?

Thanks!



---

It is NOT possible to over stabilize a bullet. The stability of a rotating object is purely linear.. turn it slowly, and will have a little bit resistance to displacement - turn it faster, it will have more resistance to displacement. The faster you turn it, the more resistance it will have to change in axial change, but there is never too much.

If a bullet comes apart in flight, it is NOT because it is over stabilized - it is because the jacket is not strong enough.

If you shoot a Sierra 55gr SP (with a 20 thou jacket) at 3800fps, with a 14" twist barrel it is stable and accurate.

The same design bullet with the same dimensions, except that it has a 9 thou jacket (the Blitz), through the same barrel...
... and it will fly apart at 15 feet. They are both stable, but the blitz jacket is not strong enough to hold together.

It has nothing to do with stability, which is the ability to resist change in axial direction in the presence of a lateral force.

I was not a believer in the fast twist is more lethal theories at first, but I am now... but I think it is limited to very fragile varmint bullets - shoot a deer with a heavy jacket bullet, and I don't think it makes a bit of difference, but shoot a woodchuck with a 55 V-Max and I have seen more "gush" from 7" and 9" twist barrels, than 14" barrels.

Of course this is not "scientific... you would need controlled studies... like a 14" twist barrel and a 7" twist barrel and targets that were identical and in identical positions...

... I would suggest imprisoned child molesters lined up at 100 yds, with chest shoots that missed the ribs so only flesh was involved... I think that would be a definitive test.

Ya' thunk? /ubbthreads/images/graemlins/smile.gif

.
 
A little bit of opinion sprinkled lightly with fact here...

Is there a difference in terminal effect that can be attributed to twist rate? Short answer, my opinion, "yes - sometimes".

The cause of the difference in terminal effect that may be brought about by twist rate is not due to simple rotational energy however. The rotational energy of a bullet can be calculated and has been, and it isn't much at all. Even for a very high velocity and fast twist, there just isn't much energy involved in the spinning.

What I believe, is that some bullets, at faster twist rates, become much more easily disrupted. Some may even be on the ragged edge of disrupting all by themselves by centrifugal force. THOSE particular bullets, in my opinion DO exhibit different terminal effect than the exact same bullet at a slower twist. The difference is not always better performance, either. Depending on many factors, including just how quickly total disruption occurs, target mass and density etc., the difference may mean more spectacular graphic display from a prairie dog (good), or it may mean surface splash and a large shallow entrance wound lacking sufficient penetration for a quick clean kill on a coyote (bad).

Lots of other subtle factors and nuance come into play. After shooting many tens of thousands of varmints, I've seen a lot of them and formed opinions on some.

And Catshooter is obviously right about bullets coming apart not having anything at all to do with stability. Bullets CAN be stabilized well beyond optimum, though. But the effects won't be noticed until much longer distances than most will ever shoot.

- DAA
 
I did see some statements from gun grabbers about how black talon bullets spin creating a saw blade type of motion as they pass thru the body literally cutting the human body up from spin. For the sake of discussion lets say that you have a gun with 1 in 12 twist. So for every FPS of velocity you achieve one revolution of spin. During the hoopla during the days of Clinton's crime bill, they were claiming that black talon bullets cut you up because they were spinning at 2000 revolutions per second(using 2000 fps as the velocity). It made for a good sound bite but was pure BS.
 
Aznative,
I think you have to calculate your impact velocity for your buzz-saw bullets with the 1 in 12 inch twist. Few handguns that fire the Black Talon bullets provide an impact velocity of 2,000fps.

For sure, the spinning bullet will continue spinning when it impacts soft resistance. However, the velocity will be decreasing in time/distance during the penetration as a result of the increasing resistance of the expanding bullet and the extra resistance of the "stuff" being pushed ahead in the soft resistance medium.

The gun-grabbers like to make their points with over-simplified physics that make no sense at the simple level they portray their propaganda. Then again, the gun-grabbers are emotion-driving and not logic beings.

Good to see you are on top of things and can tell mud from that other dark stuff.

Good hunting.
 
The Black talon stuff was pure BS by the liberals.

My thought on that was this..."If I didn't WANT to hurt the guy, I wouldn't have SHOT him."

DAA, I can see where a rapid twist with the right bullet can disrupt the bullet and cause greater wound trauma.

I was afraid of splashing as well.

I shot a 25-06 with 90gr HP's at a very hot fps out of a 26" bbl. & saw splashing on everything that was big enough to provide mass.

I could see that happening with something like Varmint Grenades at high velocities out of a .22 caliber as well.
 
rockinbbar,
I recently read an account in the VHA magazine or Precision Shoothing Magazine, about .375H&H Mag. bullet performance on cape buffolo. The gist of the essay delt with rifling twist rate and effectiveness of the 300 grain solids on the front chest shot. The constants were velocity and bullet weight, the variable was the rifling twist rate.

The faster twist rates seemed to be less effective at penetrating and "stopping" the big critter.

The sligtly slower twist rates seemed to be better stoppers and penetrated more deeply.

I do not have direct experience just yet but found the essay of interest. If I find which issue (and which magazine) contains that essay, I will reference it for you.

Good hunting,

Karl in Phoenix
 
Quote:
AS far as i know (im no expert) but the twist rate is totally for stability. I think either a bullet is stable or it isnt. How long it holds stability, depends on a number of things.



I wanted to expound on this bit, I like Karl had just read an article in a publication that I cannot remember the name of but If I can find it I will also post it up.

What I wanted to expound on was the idea of bullets becoming unstable when they become subsonic or pass through the trans-sonic stage. This too is a myth, at least at real world distances i.e. out to 1,000yds and actually further. If a projectile is stable at the point of exiting the muzzle it WILL remain stable throughout it's flight regardless of distance or speed when it arrives. We all saw the post the other day about shooting a .223 to a distance of 1 mile, yes the shooter was using a 1-8 twist and 90gr VLD's but he did it accurately, so obviously the projectile was stable and subsonic at that distance. So the only factor that figures into the equation of "How long a projectile will remain stable" is.....Was it stable at the muzzle?

Chupa


Edited for spelling
 
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Quote:
We all saw the post the other day about shooting a .223 to a distance of 1 mile, yes the shooter was using a 1-8 twist and 90gr VLD's but he did it accurately, so obviuosly the projectile was stable and subsonic at that distance.



I assume its Jerry Teo you're referring to, in which case he was using 80 gr Amax bullets.
 
And to answer the original question.

A lightly constructed projectile spinning at a higher RPM will destruct more violently. Equate it to a Skil-saw blade, would you want to be near a disintegrating blade as it's cycling up to speed or when it has reached it's max revolutions?

Chupa
 
Quote:
Quote:
We all saw the post the other day about shooting a .223 to a distance of 1 mile, yes the shooter was using a 1-8 twist and 90gr VLD's but he did it accurately, so obviuosly the projectile was stable and subsonic at that distance.



I assume its Jerry Teo you're referring to, in which case he was using 80 gr Amax bullets.



That may be the one, for some reason I had the VLD in my head.

Chupa
 
DAA and Chupa pretty much nailed it.
The more rapid expansion in faster twist barrels is really noticeable shooting ground squirrels. I have been shooting ground squirrels with 55V-max out of my 9" twist 223 alongside a friend shooting the same thing in a 12" twist. I get much more violent expansion from the 9" twist. When you shoot hundreds of squirrels side by side the difference is readily apparent.

Jack
 
Quote:
The more rapid expansion in faster twist barrels is really noticeable shooting ground squirrels. I have been shooting ground squirrels with 55V-max out of my 9" twist 223 alongside a friend shooting the same thing in a 12" twist. I get much more violent expansion from the 9" twist.



Not having had the opportunity to shoot sod poodles .. sniff /ubbthreads/images/graemlins/frown.gif .. I have to ask if that's what causes the 'helicopter effect'?
 
"Not having had the opportunity to shoot sod poodles .. sniff .. I have to ask if that's what causes the 'helicopter effect'?"

You get some serious "air time" with the 55V-max from a 9" twist barrel.

Jack
 
Now I know why my .223 twisted 1:7 spouting 60 Vmax's gives dirt naps quicker than anything I've ever seen....grin...

I am also in the crowd who does believe a quicker twist with the right bullet will create a more violent terminal effect...
 
Rockingbbar, I played around with two different rifles shooting p. dogs, the first was quite by accident. Years ago, I shot thousands of rounds on p. dogs, and we always put together a drop shipment from Sierra Bullets. One of my favorite bullet was the Sierra 55g BTHP, a fairly tough bullet to use on P. dogs.

Well, I got the AR bug, bought an H-bar and put a Leupold 6-20 on it. Worked up a load that shot 3/4" with the 55g Sierra BTHP at 3050 fps, calibrated the knobs out to 300 yards.

I also had a custom 1-14 twist rate Hart barrel on a tight neck 22/250, and I worked up a load with the Sierra 55g BTHP at 3650 with IMR 4064 shooting 3/8" groups.

I could not wait to get that AR on a dog town. I had 17 thirty round clips and 30 twenty round clips, and I had ammo cans full of 10 round stripper clips loaded with the 55g BTHP's. We get on the first dog town and I told my buddy to watch the action. Dogs were crawling like locusts out in front of us for as far as the eye could see. As the dogs were shot, they took off up in the air like bottle rockets! I would shoot two or three by the time the first one hit the gound at times! My hunting partner whimpered, "You are killing them all"!

As I would empty a clip, I would let the barrel cool on the AR by shooting the Rem 700 22/250 with the same 55g Sierra BTHP. Dogs rarely flew in the air, it just knocked them over. I found it very hard to believe that the same bullet at 3050 blew up the p.dog better that at 3650 fps. I had 1000 rounds loaded for the 22/250 and 1500 for the AR, the 1-7 twist rate sure made a believer out of me on making those tough bullets blow up better, transfering much more energy to the p. dogs.

So, I went home and ordered a 1-9 Hart barrel in 22 Caliber. I put this 1-9 twist barel in a very accurate 22 PPC caliber to shoot dogs with. I loaded up the 22/250 with the Speer 52g HP at 3600 and in the 22 PPC, I loaded up the speer 52's at 3550 fps.

When we got on a dog town, I saved these two guns to shoot dogs with beginning at 250-300 yards. ONce again, the 1-9 twist got the bullets to open up better than the 1-14 twist rate, but this time both rifles were shooting at approximately the same velocity. If the bullet jacket opened up quicker, then more energy was transfered to the p. dog, thus it blew up the dog better.

I worked with a Colt Govm't model and a Colt CAR also. I can tell you this, that the faster twist barrels have a more finite powder range that they will shoot accurately in vs the slower twist barrel. This was again demonstrated in a 1-9 twist 22 cak hart barrel in 223 that was put on an AR built by Bill Wilde. This particular gun was unreal accurate, but in a very narrow powder range. The gun that Bill Wylde built had a 28" Max Heavy Varmint contour on a Colt AR action with a double set trigger, and this rifle would agg in the .285 range...it was [beeep] on wheels on a dog town.

I hope this example is what you are looking for.
 
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