I would live with the fixed choke barrels until I could find a set of Mobilchoke barrels. Any other solution would be adding money to an old gun that you will never get back. No one that I know of will thread your barrels to the Mobilchoke pattern. If you find someone, let me know. I have two guns that I would like to have threaded. Don't grind your chokes out. The original barrels are chrome plated and the ground out chokes will rust.