Originally Posted by 300MagLover
Is this (1:10 twist)too slow a twist to stableize the light 150' and 165's?
No, not too slow. It's too fast. For bullets of similar styles for the same caliber, lighter ones shoot most accurate with slower twists 'cause they don't need to be spun too fast to stabilize them past 1000 yards. Example: Sierra 155 grain Palma bullets leaving at 3000 fps shoot most accurate with a 1:13 or 1:14 twist. If one has a batch of bullets that are perfectly balanced, then one could use a faster 1:10 or 1:11 twist, but this happens rarely. Most 30 caliber magnums have a 1:10 twist barrel so they'll shoot 180 grain and heavieer bullets pretty good.
At 300 mag velocities with 150-gr. bullets, they'll probably shoot the most accurate with a 1:13 or 1:14 twist. A 1:10 twist will shoot even slightly unbalanced, 150 grain 30 caliber bullets at the speed max loads in a 300 mag produces, some of them won't be too close to where you aim them.
I've shot 150 through 180 grain bullets from a .300 Win. Mag. with a 1:12.7 twist, 26 inch barrel very accurate at 1000 yards, about 1 to 1.25 MOA from a 9 pound rifle with scope.