Only place you can use anything above .45 cal is army and even then its rare
You don't know what you're talking about.
I'm pretty sure everything above .45 cal is illegal to fire let alone own in most, if not all states.
Nope.

This is our 50 Desert Eagle from IMI Research. It fires a round bigger than your thumb with the impact force of a semi truck. It is legal to own, it just has to be registered.
I don't see why you're afraid of gun enthusiasts. It's totally irrational. Just because someone is enthralled by guns doesn't make them dangerous. I love guns, I'd own more if I could, but that has no bearing on my morals.