I know i'll probably get hate because this is been asked probably a million plus times, but I haven't found a definitive answer yet. Which is better to shoot from an M1A? I know both will shoot just fine in the M1A. I'm asking because I want to know which will cause the gun to have more wear? Which will shoot more accurately? Thanks in advance.
You can't get a definitive answer because there is none, only opinions.
What I do know is regardless of which you shoot, if you reload, the only sizing die you'll find available is in .308.
To avoid pressure issues with commercial hunting loads, I believe if you keep the velocities below 2600 fps and bullet weight below 168 grain, you'll be OK.
May get corrected on that.