I have a Rem. 870 12G as well. Great shotgun. I prefer, however, my bolt-action Marlin 512 slugmaster. It's hard to beat a bolt-action for accuracy. I can hit the same hole at 100 yards with the Marlin. I got mine off of gunbroker for about $300. The only drawback I see with the Marlin is that it is heavier and kicks harder than the 870 (but not that bad).

Marlin 512 Slugmaster 12G