I'm way behind the curve on T/C muzzleloader info, but I don't think they ever offered the QLA on handgun barrels. As you say, I do know that the early barrels did not have the feature, and that seemed strange to me at the time. A good Smith could counter-bore the muzzle and give you the same effect. Local black powder guys were doing that here in the mid seventies, long before T/C.