Any centerfire rifle (maybe pistol too?) over .5" bore is considered a "destructive device" according to the ATF. Black powder and shotguns over .5" bore are exempt from DD status.
Personally I would rather be shot with a .50 BMG than a shotgun with a deer slug. Those things are really nasty... not overpowering you-don't-have-a-chance powerful like the big gun but just really ugly when they hit meat and bone.
Saying things like this is just more ammo for the anti gun crowd. Guns are not destructive devices by nature. When you shoot a deer do you aim to destroy it or do you aim to kill it while otherwise not damaging the meat? When someone breaks into your home do you try to do as much damage as possible or do you first show the intruder you're armed so he'll leave before any damage is done and only fire if absolutely necessary? In combat you come across a man with 60+ lbs of explosives and shrapnel strapped to his chest in a crowded market. Do you aimlessly start shooting and hope for the best or do you take him down without setting of the explosives and save hundreds of lives?
Back to the large caliber fun! Legal or not bigger bullets are always better, rate of fire is just icing on the cake.
I was refering to the cartridge which is used in many weapons, not the actual M2 browning machine gun.
Guns were not intended to punch holes in paper, they were designed as an instrument of war. They can and will be destructive depending on user. The only defining thing about if they are constructive or destructive is which way they are pointed.
A .577 or even a .50 BMG would destroy a deer. I know a guy that has tried deer hunting with his 45-110 Sharps and it destroys whatever end of the deer he shoots.
Personally, I would rather have the Sharps and run 45-70 thru it than a .50 BMG anything... unless reselling the .50 and buying what I want is an option.
.50 BMG is the name of the round.
http://www.cabelas.com/catalog/search.cmd?form_state=searchForm&N=0&fsch=true&Ntk=AllProducts&Ntt=.50+BMG