What can I do to help my new M1A standard to shoot better than 4to5 inch groups

[vintage hunter]

I agree with Cinders that more info is needed. M1A's have a mind all their own and diagnosing accuracy issues can be a pain to sort out. You say you're getting 4-5'' 100yd groups, how many rounds each? AFAIK standard models have GI contour barrels that heat up fairly quick and if your firing strings of 10 or more that may well be with the accuracy expectations of the rifle. If it's 3 or 5 rounds each then there's likely a problem somewhere.