Sorry to say it, but I think the whole idea that he was wounded while "fixing" a dented round is the work of fiction. I can't even speculate as to what really may have happened but this smells like a cover story to me.
After Desert Storm while waiting on a flight home a bunch of us heard about an E5 who had blown his hand off trying to stuff a cluster bobmlett in his duffel bag. Everyone agreed he was unlucky. I said no, he was stupid... the other 300 GIs waiting to get on the C5 with him were lucky.