i have numerous mossbergs from the 500 to the 835 and a slug gun to and my father has numerous mossbergs as well and it seems that the only shells that shoot and group good are Federals. I took the stock mossberg choke out and have a carlsons choke for each type i use them for like turkey/deer/clays etc etc. but every gun is different. so make sure your barrel is clean as it can get and no damage and then do a little more research on choke tubes that you would be interested in. And try some different ammo.It might cost a little bit to find that perfect combo but its out there for ya!