Yep, send it back to TC and get it fixed, I would not settle for a Black Diamond or even an Omega. Not my intent to knock anyone's gun, but I think TC screwed the pooch when they dropped the Firehawk and it's 1:38 twist bbl, Thunderhawk too. Most of their guns shoot good, nice thing about the Firehawk series was they shot alot of different loads very good, and with a little load tweeking they shot many of them exceptionally good, conicals, sabots, BP or Pyrogeek. Sorry for the large picture but it's from the 90's and done on a scanner (Pre-Dig Camera), the orange dot is 2" so it's about an inch group @ 100, 1935fps. It's the least fussy muzzel loader I've shot.
Doug