Home Forums Hunting & Shooting Hunting Rifles Does anyone think a faster twist helps with terminal performance?

1-8” 7 Mashburn

Not sure how it kills any different but when you see the friction of the RPMs against the frontal diameter of the bullet it would seem to have to keep rotating in order to bend the petals in the propeller type way. If it was merely just turning over at the same rate of 1 turn in 8 inches I don’t believe you’d have that same effect, but I’m just a student of this. Cool to see others points as well.

It does take a relatively robust bullet like the BBC or a heavy TTSX or similar to see it.

A standard bonded bullet like an Accubond or Swift doesn’t show as well since it doesn’t really have petals to bend as it sorta balls up.

It's a known fact that a lightly constructed bullet at high velocity and high RPM can disintegrate in flight.

So the answer in my opinion is yes, sometimes. There are a lot of variables though. Bullet construction, twist, impact velocity, impact medium, etc, etc.

I always wondered about this with heavier bullets….Faster twist will have more recoil.

Once you have enough energy to expode the target like that it would be hard to expode it more.

This would be more about getting a bullet to expand that might be on the edge of not expanding and in larger animals that don't explode.

As Shane said it's possible to get bullets to expand on air if the twist is high enough and the jacket is thin enough.

Are they expanding or simply coming apart? That is - they're not mushrooming but spinning apart where he jacket and core aren't 'mushroomed' but spun apart like a fidget spinner.

In the split second before a bullet comes completely apart, doesn't it expand? If the rotational force is excessive the bullet comes apart, but if not excessive it would just expand I would think.

I took JB to mean "expand" in the common sense of a mushroom given the use of "expand on air" not "expand in air"

I do believe that the somewhat higher rotational speed of a bullet from the faster twist barrel does aid in the opening up of the bullet. To what degree I honestly do not have a clue. Whether or not it makes a difference in the demise of an animal may in the long run not mean much AFAIK.
Paul B.

Beretzs' photo of the non-fragmenting bullet is very convincing. It clearly shows how each of the petals is opened up more on one side than the other - indicating that at least some of the expansion was caused by rotational force rather than frontal force. It indicates that not only did the rotational force give more expansion, but also the "cutting effect" (caused by the shape of the petals) that rotational force would give in the larger wound channel.

I've asked many guys who Bitch about Bergers exploding on game what twist there running say 8 vrs 10 in a 30 cal not one would answer me. A 10 twist out of a 30 cal running 3050-3100 and a 215 isn't gonna act the same as a 8 twist.

Varminting is the only reference I am applying my experience to, as the only time I have had others claim fast twist was more volatile than 1/12 or 1/14.

In big game, I have no comment, although the one picture of the bullet with twisted petals, does look like spin may have an effect. Making something more dead due to twist, may be similar to the caliber argument that never gets settled…

The answer might be "it affects terminal results" but no one can determine "help" or "hinder" at this point.

I don't know whether it would make any difference in a big game bullet. I know for certain that when that when I rebarreled my 22-250 from a 12 twist to 8 twist that the impacts on prairie dogs got much more dramatic shooting the same bullet (55 gr ballistic tips) at roughly the same velocity. The bullets shot from the 8 twist seemed to expand quicker and give more dramatic theatrics from the hit prairie dogs.

I doubt that any animal killed by a bullet died as a result of twist. I’m sure someone already said this earlier in the string, my fingers that they did, I love the debate aspect of it, not the results of it. Come opening day the Fire sings a different tune and that’s music to my ears!

I just had a look at some mushroomed Barnes TSX's - .270 130 grain and .338 225 grain that I have. Both showed all the petals skewed in the direction of rotation. The point being that the rotational force has a significant effect on the 4 petals. I would conclude from that that a slightly greater rotational force would have a slightly greater effect.

At what MV and rifle weight?

Bryan Litz did a FB post where he showed the difference in KE for rotational velocity of a 1-10 vs 1-12 bullet for a 250 gr bullet out of a 338 lapua and it was about 13 ft-lbs. keeping things equal the lineat KE was 13 ft-lbs less. His main point was faster twist does not result in much velocity loss. The point being the total KE stays the same if want to keep things equal by adding twist, linesr velocity will be little lower at same pressure. So, there are a few ft-lbs more rotational energy in a faster twist at the expense of linear KE. In a varmint bullet probably why see more pop. In a big game animal maybe shows as very slightly wider wound at expense of very slightly longer wound. However the vast majority of KE is still linear. In the case of the lapua it was 4348 linear / 29.3 rotational for 1-12 and 4335 linear / 42.1 rotational for 1-10

Lou

Does it specifically say pressure was kept the same, and if so, do you know how he kept pressure the same? I would think he would need to drop the load slightly with the faster twist to maintain the same pressure.

I'd go with that. I just haven't found a spot where more RPM's hurts accuracy in hunting rifles with hunting or even ELD/VLD type bullets. I have heard of cut rifling being harder on some jackets, but not twist in and of itself.

I have been using 1-7 .224's, 1-8 264, 1-7 1/2 6mm, 1-8 308, 1-8 7mm, 1-10 375's, 1-10 9.3 etc for a bit and can't find the downside myself. I haven't vaporized any bullets and they've all done great with light bullets and especially with the heavier variety's.

No he did not say same pressure but same load. I inferred the same pressure part since linear velocity was deceeased for faster twist. So I would think if you want to keep same velocity pressure would increase

Lou