Re: 1 in 12\" twist in 300 Ultramag
I do get great resuls with the 200 AB in a 12x Lilja barrel. I have shot these loads out to 650 yards to date. In cold dense sea level air, they are stable at 650 yards. Accuracy with my best loads is about .3 MOA Velocity is 3147 FPS out of the 300 RUM. 12x is very slow for the 200 AB. 12.3 would be borderline unstable, but if youre getting them to stabilize, you dont need to worry. I also agree with others here about the 180 AB. My 300 12x likes them a bit better in the accuracy department.
Long range shooting is a process that ends with a result. Once you start to focus on the result (how bad your last shot was, how big the group is going to be, what your buck will score, what your match score is, what place you are in...) then you loose the capacity to focus on the process.