How old is the gun? It may already be drilled and tapped for a rail on the receiver. Most newer mossbergs are, at least the 20 and 12 gauges, not sure about the 410's. That or you will need a receiver saddle mount or drill and tap the receiver.

I'm not a big fan of mounting scopes to the receiver of a gun with a barrel that can be removed easily and isn't pinned to the receiver. It will not be the most accurate set up you can get.

I agree with the above, Some decent clamp on fiber optic sights would be perfect, especially considering the limited range the 410 will have. Also will be much cheaper in the long run, you can get some really nice clamp ons for less than it will cost you to get a scope, mount and rings. And you won't have to change anything when you want to small game hunt with it.

Paul