Thanks for answering.
Sounds like a good idea to check on barrel steels. Wasn't aware there was that much difference in barrel steel with the Sportster barrels and regular rifle barrels.!
Also, the .22LR is .222 caliber and the .22 Mag is .224 - same as the Hornet, K-Hornet and Fireball. I would never attempt the project I'm comtemplating by modifying a .22LR barrel.
My desire to use a Sportster could possibly happen as a result if a bull barrels is offered for that model, but not (a heavy barrel) for the .22 Hornet in a HandiR. In both the .22 K-Hornet (Kilbourne Hornet) and the Fireball, I want the barrels to have a lot of steel in them! Not the thin light-weight tapers.
Apparently I need to place another phone call to Gardner, MA and talk to a tech.