One of our local Game Wardens just bought a .50 BMG, single shot bolt action. He plans on shooting an elk with his. The guy is one heck of a long range shooter and he has more damn charts, graphs, etc. taped to his stock than you can believe.
There is a trend of limiting the overall weight of rifles in some states in an effort to effectively outlaw rifles like the .50 BMG. Some folks believe such firearms encourage folks to attempt unethical and unrealistic shots at ridiculous ranges. Could be some merit to that I suppose. Then again, it is legal to buy a "normal" rifle like a .270 model 70 the day before season, bore sight it, then go out and gut shoot everything in sight. Kinda tough to legislate smarts...