All the missed shots have been from 50-80 yards.
I am guessing I'll have to wait til spring and make a few trips to the range to double check my groups with the 870. If things aren't where I want them it might be time to invest in a muzzleloader! Unles I see a good deal on one before spring, then it might be muzzleloader time anyway.
Another benefit or a muzzleloader is that it might make me concentrate more before pulling the trigger knowing I only have one shot.