Hello,
I was looking at getting my son a rifle in 308 for deer/hog hunting and noticed about half of the manufactures have 1:12 twist vs 1:10. Berger twist calculator shows 165 and 180 grain bullets marginal for stability. In real world shooting has anyone had any problems accuracy problems shooting up to 180 grain bullets (including monos?) I assume up to 180 grain bullets shoot fine or this is something that would have been discussed at great lengths on the forums. Thanks
I had no problems stabilizing 175 gr bullets with a 1:12.
People who have shot the 308 a lot will know that a 12 twist will stabilize any bullet up to and including, the 200 grain Matchking, all the way out to 1000 yds. It is unlikely one would use a hunting bullet which is longer than that. GD
What does stabilize mean - bullets are minimizing drag (optimizing ballistic coefficient [BC]), aren't keyholing, or something else?
Something that's often neglected in these threads is elevation. Air density makes a significant difference if you're taking about optimizing BC. Someone who lives and hunts at 5000 ft could have different experience than someone at sea level with same bullet, twist, and velocity.
According to the Berger BC program, the 200 MatchKing started at 2500 fps is "marginally stabilized" at standard conditions (59 degrees Fahrenheit, sea level) with a 1-12 twist, which means it's not optimally stabilized for ballistic coefficient. But it does stay above transonic velocity at 1000 yards, which means it remains stabilized at least out to that range. Of course, higher elevations will result in better BC, as long as the temperatures not a lot colder.
A 1-12 twist is more than enough to stabilize a typical 180-grain soft-point hunting spitzer.
the 1-12" it will shoot all factory loads and kill at all hunting ranges.
If you want to do some crazy handloading and shoot at a mile... you will probably need something else. like a 338 Lapua =]
For most hunting, either 1:12 or 1:10 will have lots of options.
Personally, I'm going toward the faster twist rates. I've got a few .308s with 1:8. I don't know any good reason to go slower, if 1:8 is an option.
I've also got one that is 1:4. I got it to test some theories. Match type projectiles blow up just outside the muzzle if fired at normal MV.
When asked why the hell I ordered a 1:4, I replied: "Because I think 1:2 would be a bit extreme".
I have had good results using 200gr a frames in 1:12 308 rifles. I actually prefer it to the 1:10. Imho the 1:12 does better with 200s than the 1:10 does with 150s
I have two different loads for 20", 1:12 twist barrel, 165gr Gameking and 180gr Hornady SST. Both are extremely accurate.
Mow, All of my hunting 308s (three now) shoot 180 gr hunting bullets without any signs of instability, at least the shot critters don't exhibit any such signs. One of the rifles I took on multiple Africa hunts where I used it a lot to shoot leopard baits (impala). My target 308s I have used to 1,000 yards with 190 gr Match Kings, no problems either...
My next 308 will get a 1-11” bbl.