I was in the army and was trained in the use of many weapons including machine guns. We were not playing soldier we were soldiers. For those who want to play with weapons join one of the military services. With all of the training we were never issued live amo unless there was an immediate need or danger. Even as highly trained as we were the army knew that having fully armed troops all the time was not a good situation.
Edited to add: I will say that a some people have the ability and mental capacity to own firearms.