Thompson/Center Arms was an American firearms company based in Springfield, Massachusetts. The company was best known for its line of interchangeable-barrel, single-shot pistols and rifles. Thompson/Center also manufactures muzzle-loading rifles and was credited with creating the resurgence of their use in the 1970s. Contents 1 >History</b>. Fits Thompson Center Hawken ; Investarms Hawken ; Lyman Trade; Green Mountain Long Hunter barrels and ... $17.50.Qty. Add to Cart. Add to Wish List. ... STRAIGHT TANG, 5/8 x 18 for 13/16" and 7/8" BARRELS Machined steel plugs, not castings.Tang length approximately 3". Threaded 5/8 x 18 for 13/16" and 7. $3150- Percussion fullstock rifle using. 3rd Party 50 Cal. Round Ball Barrel for Thompson Center Hawken or Renegade. This is a 3rd Party drop-in barrel that is made for Thompson Center Hawken or Renegade rifles with a 1" barrel channel. The barrel is 31" long including the breach plug. It is.50 Cal with what I believe is a 1 in 66 twist rifling. USED VERY GOOD CONDITION THOMPSON CENTER HAWKEN MUZZLELOADER .45 CAL -- 29" OCT BARREL -- WALNUT STOCK -- DOUBLE SET TRIGGERS -- WOODEN RAMROD W/ BUSHNELL SCOUT RIFLE SCOPE 2X32MM PLEX MOUNTE ... SOLD A fine Thompson Center Hawken wirh a serial #59990, .50 cal., 28” octagon barrel with a bright excellent bore..