Don't take me wrong, I want you to be happy with your 500. Most 500's have 2 beads on the vent rib. If you put any effort into using both beads you will see they shoot a slug accurately enough to defend your home. I can't recommend smoothbores for hunting deer. A rifled barrel is very accurate and most newer 500's are already drilled and tapped for a scope.
Another problem you run into with ghost rings on a shotgun is your eye naturally goes to the center of the ring, which will result in shooting over your target.