No one makes a drop in after market barrel for the BT65 to my knowledge. You'll have to get a replacement from Hatsan, or try and track down a European LW barrel for the BT(that was an option). Otherwise, you'll have to have one machined to fit... I say just order another one from Hatsan and hope for the best. FYI, the barrels for the original Nova, Bullboss, Airmax, and AT44 are the same barrel. Good luck!