General consensus has been bullets from 145-175 gr with powder and too slow or too fast that provides reasonable velocity and importantly port pressure. Some also have great success with bullets as light as 125 to 135 grain. Most 7.62X51 loads (and NATO specific) fit this tho I believe some have posted a few odd balls that are not. Many commercial ammo will fall in this suitable range, just need to look at velocity as a guide although that will not always tell you if factory powder is too fast or too slow. The super performance and hot loads generally are not recommended.I know i'll probably get hate because this is been asked probably a million plus times, but I haven't found a definitive answer yet. Which is better to shoot from an M1A? I know both will shoot just fine in the M1A. I'm asking because I want to know which will cause the gun to have more wear? Which will shoot more accurately? Thanks in advance.
Just as you indicated this has been asked million times and will be asked another million. Just as often as what is the real design ammo pressure. Believe many have indicated the military spec of 50 kpsi is misleading because of different pressure units ( 50kpsi may (?) have been CUP units which is ~ 60 kpsi). Ammo within desired pressure limits do not always mean ideal port pressure.
Confused? Of course that is why it (they) will be asked another million times because it is not one simple answer.