Home Forums Hunting & Shooting Custom Rifles & Wildcats .280 Remington / rate of Twist

I have seen tests done with pressures in different twists and the difference is so small as to be nearly undetectable. The biggest resistance is in getting the bullet engraved in the rifling, and whether it is 1-9 or 1-10 (or even 1-8) has hardly any effect.

Today's bullets are in general so well-balanced that "over-stabilizing" generally has very little effect. I once had a .260 Remington built with a 1-8 twist Hart barrel partly to see if it made much difference with lighter bullets. It shot everything down to 95-grain Hornady V-Maxes into under .5, and even 85-grain Sierras went just over .5--and I didn't really try many powders either.

Also, today's bullets just keep getting longer and longer. Stabilization has to do with length, not weight. Today a really long 150-grain 7mm can be longer than any of yesterday's 160's.
Throw in the possibility of shooting at different elevations (it is indeed harder to stabilize longer bullets at sea level) and I tend to err on the side of faster twist.

Other examples: The most accurate individual 7mm hunting load I have ever shot was pretty much standard load of IMR4350 and the 140 Nosler Partition, for a muzzle velocity around 2850 from a 21" Shilen barrel. It would literally put 5 shots (not 3) into .5 inch. This was in a 1-9 twist. I have also gotten fine accuracy out of 120-grain Nosler Partitions and TSX's in a 1-9 twist from a .280 Ackley at over 3300 fps. If they suffered from "over-stabilization," it wasn't showing up on targets.

You may not want to shoot 175's. but you may want to shoot a really long 150 or 160 someday. With a 1-10 twist it might not work. With a 1-9 it will--and it will still shoot light bullets.

The other way around does not work. I had another custom 7x57 made once, and the maker asked me (without telling me why) what bullet I would mostly shoot. I said 140 Partitions, so unbeknownst to me he put on a 1-11.5. It shot 140 Partitions real well (though not as well as that 1-9 Shilen barrel mentioned earlier) but sprayed 150 Ballistic Tips. That was when I measured the twist and fond out I'd been screwed.

JB,

Thanks for replying to this thread, your experiences are always good stuff!

In one of the many past VHS magazines, Ken Howell wrote an article on over-stabilization of bullets at long ranges complete with some graphics depicting how a faster twisted bullet travels with it's nose pointing straight when descending downward in it's arc at longer ranges. According to Ken's article, the bullet's nose should be following the arc's path instead of "nose straight".

Don't know if I made sense (above), but I do remember calling Sierra bullet's hotline and asking why the 12 twist is so popular in the 308Win. The tech stated it was a more accurate twist with bullets up to the 190SMK at the longer ranges. And maybe why the Marines are so fond of it?

Since then and building many more rifles I have gravitated towards the faster twists although not always the fastest twist. (for example 11 twist in the 300WM, it's great. 9 or 10 twist in the 7mms).

MtnHtr

I Do have another question. Why is the 1:10 twist universally recognized for the .270win. I mean those .277 150 bullets are pretty Long! Make them 150 TSX and....hello...
Shouldn't the 1:9 be more popular there, than it is?

I have a 280 with 1:12 and 1 with 1:9.25. The 1:12 does very well with lighter bullets but doesn't like the 160 target class bullets. It does shoot 175 Nosler Partitions well, but I figured that had to do more with the stubby shape than weight. The 1:9.25 shoots 120 - 160 very well. I have not tried anything heavier. It also does build pressure faster. I'm betting that it is the fact that it has a much tighter chamber and throat rather than the difference in twist. - Denny