I've looked into this and it seems about the best solution would be to take it to a gun show and find someone that has a large selection of new/used barrel extension and find one that goes hand tight to about the 10:30- 11 o'clock position. I've seen these barrels for sale for a while and I have to wonder why anyone would take a barrel extension off in the first place. If they have the sights and gas hole drilled then they've had a barrel extension on at some point since these steps are done after the extension is put on. The only thing I can come up with is that it didn't headspace correctly in the first place or there is a problem with the bore. If its a headspace problem, then you'll most likely need a lathe, and/or chamber reamer (if its not chrome lined). You could always screw on a extension verify its headspace, then cut it off at the gas port and make a pistol barrel out of it. I don't like the idea of plugging the gas port and drilling a new one and new sight base holes. All of these options seem like they're more trouble than they're worth to me though.