Bill Wilson from Wilson Combat sent this quote over too us. Wilson says he found it on one of the survival forums:
“There are only two times when there is such a thing as too much ammo. One is when you are swimming, the other is if you are on fire.”
I would submit that “too much ammo” might be a hindrance if a pride of man eating lions were on your heels. Of course, if you can shoot fast and accurately, and have a repeater, too much ammo might be just the thing.