The T/C Big Boar came in a Hawkins or Renegade stock. They had a 1-48 twist barrel. And it will be stamped on the barrel "Big Bore." Why they considered the .54 a big bore when it used to be so common I can not say, but the .58 caliber is starting to push the big calibers. The bore was supposed to be .580. So I would shoot 100 grains of 2f powder and a .570 ball with a good thick patch. Also because of the twist they shot conicals pretty good. I tried to get one a few months back, but bidding was crazy on the thing. You found a heck of a rifle there. Good luck shooting it. The manual for it is under the traditional rifle section which covers the Hawkins and the Renegade. In the back you will find load data for the .58 as well as I remember.