My brother has a .500 it's fun. =)
I'm decent with my 9mm, but my grouping isn't the best. Before school (and the subsquent lack of money/time for the range) I had a pretty consistant 2~3" grouping at 10 yards. Usually spread to like ~8" at 15 yards though. That was also pre-LASIK though, need to go waste some money and see how much I've regressed over the past year.
Doubt I would even be able to hit the target past 15 yards with a .500.