I have wondered that myself and even asked Knight a few years back and they said to never load round balls in that gun due to the "jug choke" design. Basically the gun barrel is smooth and has a constant bore sizeup to the last 5 inches or so then gets a larger boresize then goes back to the constant bore size before exit. It's made for shot to expand then constricts it all before exit and provides for awesome pellet groups. I saw a website that claimed you could remove the choke tube and shoot 69 cal roundballs out of the gun. I was going to do it until Knight said no way. I guess a gunsmith could modify the barrel (cut off the Jug choke) and one could possibly shoot that size roundball but why it's a great shot-gun.