I've never shot any BG at 500 yards. But if I were so inclined, I think a 7 mag with a good 3x9x40 pushing a 160gr bullet would be a good start.
I do know it will make holes in paper that are very close together at 600 yards. And that's from field positions. The only difference is my 7 mag has a 2x7 on it. smile


Aim for the exit hole.