First, I would use/get a bore scope to determine what the barrel restriction is all about. It may just require the use of some JB bore paste on a mop with lots of elbow grease to remove the restriction. Second, if you want, you could have the barrel re-bored to a larger caliber. Third, you could go on e-bay or one of the other sites and look for a barrel for your gun in a caliber you would like. Just make sure you get a barrel that fits your gun. I believe the .54 T/C Hawkens guns came with a 1" across the flats barrel, so any Renegade barrel should fit with some minor modifications.