M1As are like .22s; there's no telling what they will like to eat until you try, but as Burt says the quicker powders usually give better results, with some rifles liking nearly everything down to RL-15. IMR 4895 is as close to a universal powder as there is. You can find a load in any caliber that will do "good enuf". That's one powder I keep large quantites of on hand for sure!