Track of the Wolf has the GMBflintlock barrel with a 1-70 twist for shooting roundball. If you want I fast twist flintlock I think they are out of stock with them... That 1-70 will really throw a good accurate roundball though with lots of power to it..

Since your rifle is the Renegade you are a 1" on the flats. Not the 15/16th. Also some trimming of the thimb rib with a dremel might be necessary to make the barrel drop into place. So if it does not go in easy, you can trim the stock, or trim the barrel.