I'm using an 870 with rifled cantilever barrel and a bushnell multi-reticle red-dot. Bench rest at the range, using the 1 MOA dot, I can keep a 2" group at 100 yds. In the field, I use the circle-dot reticle, or the 6 MOA dot, and I know the slug is going inside it, which is good enough for a kill as most shots are still w/in 100 yds.