A while back there was a line of magnums promoted called the "Barnes QT's" I recall various bores and in particular a 6.5mm with a twist about 5.5"!

The claim was that the fast spinning bullet would tear up the target and kill much better.

What do you remember?

The tighter twist will increase the gyroscopic force that holds the bullet stable on it's axis. It is less prone to tumbling or veering off line in the target. Providing it does not come apart, it makes for more reliable terminal performance. The same effect can be achieved by using shorter than normal bullets or bullets that become shorter upon impact.

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Gerard Schultz
GS Custom Bullets

The argument on the QT's was the damage done FROM the spinning of the bullet. If the bullet went thru the ribs of most animals it would not turn much I think. If it stopped or almost stopped then more damage might be done. The QT was supposed to do a lot more damage due to the rotation while the bullet was in the animal.

I have read here the statement from GS that a bullet that stays straight on will perform better. Lets accept that for now with bullet that can expand.

I think the proponents of the quick twist barrels mistate what the advantage of the quick twist is.

I do not buy the "buzz saw" theory of the high rotation bullet.

What I do buy is that a bullet with a higher rotational velocity will upset more quickly then a slower twist. Therefore, this would have the same effect as a less stoutly constructed bullet. I also have no doubt that convential barrels when firing lightly constructed bullets can be oustanding killers if the bullet makes it into the vitals. They can also fail miserably if the bullet blows up on impact, and fails to penetrate.

I agree with Paul H, which is often the case. Manufacturers keep trying to sell exlixers and magic bullets. The truth is you have to hit them in the right place with a bullet that will penetrate to the vitals. That will kill them. Not the new hydro velocity super round hitting off target. If you miss with a .5" bore you will still have a wounded animal, same with a projectile that is spinning wildly.

I also don't buy the theory that a faster spinning bullet will do more damage. Consider that a conventional twist bullet is rotating around 200,000 rpm when fired vs. say 300,000 rpm (just guessing) with a fast twist one. Given the forward velocity of the bullet at impact then the bullet is still going to travel through the animal so fast that it's only going to twist one or two times during it's penetration. That doesn't seem like a "buzzsaw" effect to me. Let's assume for argument's sake that the animal is struck by the bullet at point blank range and that the bullet doesn't shed velocity as it goes through the animal. If it's shot from a barrel with a 1-10 twist then the bullet would rotate once every ten inches inside the animal, which is about the depth of a deer's chest standing broadside. If it's shot from a 1-5.5 twist barrel then it's going to rotate roughly twice in that same animal. Neither of these seems like it would do more damage than the other, but I could be wrong.

I have shot a lot of kangaroos with the 100 grain Hornady in the 270 and 130 Speer Hollow Point in the 308.

What has always puzzled me is the performance of these bullets on roos hit at around 500 yards.

The ballistic tables are suggesting velocities would be down at 1500 f/s or so. Yet they are vey effective.

Now if the bullet does not loose much rotational velocity, then the "twist" becomes about 1 in 5 or so at that range.

I sometimes think that since the bullet has been in the air for some time on those long shots that the centrifugal force has perhaps weakened the bullet.

Mike

Mike,

The centrifigal force, or rather centripetal acceleration is acting on the bullet from the moment it leaves the muzzle, trying to pull the bullet apart. It stands to reason that this force, in addition to the impact is what causes a bullet to upset. If we keep impact velocity the same, but up the rotational velocity, we should see a more dramatic upset on the bullet.

As I recall the winchester failsafe bullet was re-designed as its performance at longer ranges wasn't as desired. They tested the bullets at reduced impact velocities at the same impact distance by downloading conventional rounds, instead of testing them at long ranges. I'll see if I can dig up the article.

I remembered an article I had read before on the .226 Barnes QT. I looked it up (Sam Fadala, "The Book of the Twenty-Two", Stoeger Publishing Co. , 1989, ISBN 0-88317-149-X).

Sam says the .226 QT was developed by Fred Barnes necking down the .257 Improved (40 degree shoulder). Bullets are .226" and weigh 125 grains, and the twist is given as 5.25". MV is given at about 2,700 fps. Sam says all manner of North American animals have been taken with it, including grizzly, elk and moose -- bullets are reported to penetrate deeply and usually exit. No claims are made about buzz saw bullets, just feet of penetration through whatever is in the way.

jim dodd

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"if you are to busy to
hunt, you are too busy."

I think jim's got the answer there. The real advantage is being able to stabilize a longer, heavier bullet than normal for the caliber. The result is better pentration. That's what made the 6.5s killer reputation, long bullets, moderate velocity = plenty of penetration.

All,

What I would propose is what HunterJim started to point out but needs to be followed up on.

The purpose of "QT'S" and other such cartridges (257 Condor, 258 Condor) was to fire bullets that were heavy for bore, not to be buzzsaw bullets based on just a fast twist. Bullets that weigh 160 grains for .257 and 200 grains for 6.5 need to be spun faster since they are of necessity longer due to their weight based on the standard construction available at the time of development. I have several of these barrels and they are fun to play with but now I need to become a bullet maker in order to get the fullest use from them as no one that I am aware of makes these heavy for bore bullets.

Bill

To also stay with the orginal topic I am sure I recall the copy as saying the twist increased the killing power. Not that long, heavy for their diameter bullets, increased killing power because in general they don't as I understand it. It's a bullet balanced for the game that does best.

Bill Davis, the famous technical writer, calculated the energy of the rotation of a bullet and concluded that is was very slight.

Not that it would not enhance expansion.

Quicker twists obviously increase bullet RPM which in turn massively (out of all proportion) increases the forces bearing on the bullet. As a result a conventional jacketed bullet loses a lot more weight a lot more quickly. The weight loss will create a wider wound channel.

As for buzz saw allthough the RPM is greatly increased, the revolutions per distance travelled is not greatly altered. So your bullet rotates completely twice in the animal instead of once big deal - it's hardly chainsaw performance. Oh and by the way AP tank killer have zero twist and they kill quite well no.....

Bill,

The material I read on the .226 QT also said that Barnes was making his own 125 grain .226 bondded core bullets, so I presume that rolling your own bullets comes with the territory with such rounds. Or else having a friend who is a bullet maker!

jim dodd

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"if you are to busy to
hunt, you are too busy."

HunterJim,

Yes, since Mr. Barnes owned his own bullet manufacturing company, he could do that. It would be a great position to be in. Mr. Clark of .224 Clark fame and Mr. Arch for the 6.5x55 Improved Arch both resorted to making their own since there weren't any bullets strong enough or heavy enough for their testing. I have purchased some of the Clark bullets from a local source in all three weights and am waiting for a break to try a few of them.

The reading that I have done on the quick twist thinking only mentioned the heavy for bore idea which required the faster twists for stabilization. In fact all of the experimenters mention the the two concepts together as being the reason for development in the first place and at least in the books that I have or have access to there is not a mention of "chainsaw effect". But I can't speak to all of the writings since I can't keep up with everthing all the time anymore. I'm not trying to be disagreeable, it's just that this concept sounds a little unreasonable.

Bill