I've shot many different commercial and surplus ammos through the M1a. I've just not gone above 175 grain bullets and have stayed away from the "superformance" or any other "magnum" type loads. Fire away! Oh, I've also shot plenty of soft tip hunting ammo out of them too with no I'll effects. Get a good chamber brush.
By the way, mine prefer the federal fusions in 165 grains. Of course to find out how accurate it is, try shooting some federal gold
Medal match 168 grain.