notropis, M70 Classics in 300 Win Mag have longish throats; long enough that you can seat bullets relative to the lands and they will not fit in the magazine. This creates a bit of "free bore" effect,and I have swapped out parts to open the magazine to H&H length to alleviate this issue.
This may be obsessive tinkering but it did help bullet to land relationship with 165 gr bullets,and actually helped accuracy with 165's; not so much difference with 180's.
When I had these rifles in 300 WM so altered I worked up with the 165 until velocities were in the 3150-3175 range,and 180's were comfortably 3050-3100, and stopped there. I never suffered any ill effects with this arrangement.
These were of course all M70 Classics.
