I'd agree; I think you're using the wrong caliber/barrel combo. Go big; REALLY big. The most accurate smoothbore I've seen was a 12 lb. Napoleon. 2 sighters - then one solid shot took out the grille and engine of an old Valiant, which was running at the time, @ 200 yds. The impact knocked the car back approx. 7 ft. and everybody was comparing it to the previous year's shot, which went completely through the engine and body of a Datsun, lodging in the trunk. This shot took out 2 cylinders, a carb, and other misc. parts. This wasd at Charlie Smithcall's annual cannon/gatling gun shoot.