This has apparently been solved, but just for the record...
Briley can 'open up' any screw in choke you might send them. They did it for me on one of their VERY thin wall tubes without breaking a sweat. This was the kind that have the threaded area elongated because the tube is so thin and the threads so shallow. It's a square thread (Acme) and they need all the threads they can get for a Winchester Model 50 barrel. My tube was a IM, and I had it taken all the way out to cylinder. Easy for that shop. They charged me $40 at the time which was less than an extra tube.
Briley also sells chokes for what appears to be any and all factory makes and styles.
It's a machine shop that specializes in choke tubes and I just bet they could make you anything you can draw or duplicate anything you send them.
