How did Pvt. Pyle in Full Metal Jacket get his rounds? When I went through a boot camp, all ammo was accounted for before you left the range.
There is a little foreshadowing about this in the film.
In the scene where Pyle is on the range, and Gunney Hartman tells him that they have finally found something he does well, Pyle removes the magazine from his rifle and drops it on the ground, then picks up a second magazine and inserts it.
There are still rounds in the magazine he just removed. The theory is he pocketed those rounds and later used them to kill Gunney Hartman and himself.
Whether he could have done that and got away with it, I don’t know. In the Marines, they manage their range pretty tightly, and I’m sure they have to police the brass and ensure the rounds are accounted for.
I went to the range about once a year when I was on sea duty in the Navy, and they didn’t keep track of anything, so you could definitely get away with it.