Rifle scopes is all I've ever used on shotguns - but as already said look for the longest eye relief you can find in a good scope.I been knocked silly a few times and drew blood couple occasions - that sucks!

Alot of guys around here are buying/using the Bushnell Banner 3-9 due to long eye relief - I believe its 5". I have 1 on a 12 and 1 on 20g.No problems with either.

Don't really need 9x.I like the 6x for down range shots on slug gun.
Hard to find 'shotgun scope' w/6x.