May I recommend that you get a copy of
Hodgdon's Data Manual. They have a section
on match loads which are intended for use
in your M1A. Your gas gun will not like some of the slower burning powders which would be just fine in a bolt action. They also show loads worked up using Winchester brass vs GI.
You will find that the folks here are rathey shy about giving out specific loading data.
can you blame them?
Good luck & Good shooting!