Hi ECS - there's no easy way to do this without a lathe and a barrel vise. The 581 series will require removing the barrel and front sight, turning the thread tenon to diameter, threading it, and then turning a shelf for the front sight go back on in its new location. Reinstallation of the barrel and front sight finishes it up. Threaded 1/2x28 and done properly you can add a plethora of things including a can if you have the means. You might find a local Smith who will do it but most likely you'll need to send it to someone. Let me know if I can be of help -
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