I'm an M1A Armorer and Club President.
My thought is that you cannot get into battery because the brass is not sized correctly. Be sure to use a SMALL BASE DIE when sizing brass for the M1A.
A Full Length Die is not appropriate for this, you must SMALL BASE the brass for this rifle.
Whatever you do, do not try to fire without the bolt fully in battery, if you do you may end up with metal in your face/head.