What he said 100%. I never use commercial ammo in milsurp guns at all. especialy since my son had a runaway sks in his hands a few months ago using rem 7.63x39. It had a stuck fp but the harder gi primers probably would have prevented it. Probably.........
In my m-14 I only use handloads with gi brass and winchester lr primers wich I have never had a single problem from in well over 40,000 rounds. No that wasn't a misprint.
The other thing to watch with commercial ammo is the powder used. Too slow and you will tear up your rifle. It's just a matter of time. A lot of 308 ammo is loaded with powder unsuitable for the m-14.