I also shoot an 870 , in express magnum has a 21 inch barrell, hastings xtra full choke I shoot winchester extended range shells in 3 inch and get 12 pellets in the kill zone at 50 yds , dont shoot at birds that far but know it hits good at that distance i agree with the other guys shoot some diff shells try a diff choke it should have come with a x full choke thats all mine came with but its a turkey gun mossy oak camo 21 inch barrell good luck