While in the Marines, I qualified with the M14 rifle. The process was simple but hard. Just before the firs day of live firing, they installed firing pins on our rifles. After the last day, they make very sure to remove them.
A couple of years after the movie, “Full Metal Jacket” came out, I watched it. I realized the movie was the most accurate depiction of Marine boot camp I’d seen, up to the point that one character was depicted of saving a bullet from the range and shooting the platoon commander.
It blew a hole in the reality an 18 wheeler could drive through. The man might have had the bullet but there no way his rifle had a firing pin. Can only guess they just wanted to force the issue for some strange reason. I don’t know. I cannot imagine them making that big of a mistake. I have talked with others since and not one disagreed with it. Just can’t figure why they wanted to ruin the movie like that.