The action only unlocks early if the gas port is not right... IMHO.
That said I rarely shot warm loads in the AR. Almost nothing but hot. For couple hundred thousand rounds... no ill effects.
M1A I think I shot normal loads though we did run a lot of 185 bergers at 600 which were way better than 168s at the time. Not that the load was hot but the bullet was on the heavy side.
Personally I'd not worry one bit. Certainly not about factory ammo at all. Some military contract stuff has been known to be a bit warm but you'd never get your hands on that stuff.
We can keep Larry Root and all his idiotic blabber and user names on here, but we can't get Ralph back..... Whiskey Tango Foxtrot, over....
| 
