Military M14's were regularly tested in endurance tests. The scoring rules were undoubtedly redefined at times, to pass specimens (Critical versus non critical failures), but M14’s regularly shot 6000 round tests without part breakage or failures.
Military parts are the best and most reliable parts for M14’s/M1a’s. Those who have “all military parts” in their M1a’s have the least part breakages.
This commercial bolt broke after firing less than 100 rounds of LC match ammunition. It was replaced at no cost by Springfield Armory.
Military bolts also broke and there were investigations which found that inadequate attention to heat treat was the primary cause. A secondary cause was the 8620 steel was not forgiving in heat treat and should have been replaced with a different steel, but given that no material change was going to occur, manufacturer's were made to pay more attention to process control.
Given that this commerical bolt broke, that tells me that subcontractor oversight is lacking.