[Porchdog]

I have a "sidesaddle" mount that I use on my dad's old 870 for slugs - it has a Weaver rail and mounts using the existing receiver screw holes.

I wouldn't have any qualms about drilling and tapping a "beater". I know an increasing number of guys who use red dots for turkey, geese and even upland hunting. If my astigmatism gets any worse I will try it myself.