I'm not sure if this deserves it's own thread since there aren't many of us running 20 gauge 870s for home defense, but Mesa Tactical has an adapter that allows us to put 12 gauge stocks on 20 gauge receivers. I'm very excited about this. I just need to decide if I'm going to get the Mesa Tactical Urbino Stock or the Magpul SGA Stock.

http://mesatactical.com/lucy-adapter-for-20-ga-remington-870-shotguns/