I reload almost all my ammo and when I feed the M1A I make sure I stay within the velocities and pressures recommended. I just don’t want to risk any damage to a fine rifle.
I think you’re wise to be a bit cautious about what SA told you even tho they’re a fine company, even if they put it in writing.
So I think the best advice I can give you is stick with the recommended ammunition or reload it yourself. You can save some money that way.
Wish I could do better, but that’s all I got.
What is your pet load for 150gr pills? I would be fine with refilling brass for it.