i shoot a doctored up 870 wingmaster with extra full custom choke. i put @ 80% of shot in a 30 inch circle at 30 yds, and have a solid, tight pattern at 40 yds.( 192 shot in 8x11 taarget) i have patterned my gun at 50yds., but choose not to shoot at over 40 yds., because i try to call them in closer than that! i too use federal shells- shot best pattern among all i tried. different guns shoot different patterns with same load. have a doctored up mossburg that hates federal 4 and 6 shot, but shoots 5s like a dream! just take the time to find a good combination and stick with it. good luck and BE SAFE!!