For the M1-A Platform try to stick to IMR 4895 and IMR 4064 .I would also suggest to stay in the Bullet weight range of 150-175 grains .The M1-A gas System and Operating Rod was designed around a specific pressure curve.If you can not find the IMR powders try to stay close to their burn rates .For a Ball Powder 748 and Bl-C2 should work.Using powders way out of this range could cause your OP -Rod to fail .
Regards Mike