One thing I have noticed about big bores is once the bullet is set in motion, it's hard to slow it down. I remember Justin Linebaugh using a .475 Linebaugh pistol, at something like 175 yards, and, the bullet retains a huge amount of energy, really not slowing down much at all, like less then 10%.
So, that said, if you launch a 500 grain bullet, at 2400 fps, what sort of drop do you have at 500 yards? How about a 400 grain bullet, at 2600 fps? These are out of a .475 Lott, by the way. Only real problem is finding a scope that can stand 100 ft lbs of recoil...