I use a Marlin model 55 that I turned into a smoothbore slug gun. I cut the barrel at 20", glass bedded the receiver and free floated the stock. I then drilled and tapped the receiver to accept a scope mount that I machined myself, the scope has to be high and left in order to clear the bolt. I use an old Tasco 3-9x32MM scope, the good ones from Japan back in the 1970's. Because the scope is mounted off center, I have an unobstructed view of my Lyman peep sight and a ramp front sight that I also machined. This gun's favorite slugs are the Winchester 2 3/4" 1 oz foster slugs. 4-5" groups at 100 yards are average, and I can hit milk jugs easily at 125 yards. I'd go into more detail but this isn't the gun review forum.