Repairing Barrel Threads

I've acquired a Dan Wesson 445 Super Mag barrel that is in need of thread repair.

It and the shroud were pretty abused. I'm guessing it was a case of a siezed barrel nut and nimrod combination. Brute force rather than proper tools and techniques to get it removed.

The threads into the frame are .675 x 40. Have searched high and low and no one makes that die, unless you want to pay for a one off custom die!

Threads are much too small for my hands to try filing the problem areas. Have looked at a couple of the thread repair tools that use good threads as a guide for a cutter to chase the damaged threads. They are about $72.

I don't have a lathe big enough to handle the barrel but have access to one. I have threaded on it before so understand the basics. I have never tried to chase/cleanup or repair threads using a lathe tho. What is the technique to do so?

Thanks,

Andre`

The big trick is recatching the existing thread on the lathe. And 40 tpi is going to be hard to see to begin with. Set up is as any barrel indicate in to dead zero and set up lathe to thread at 40 tpi. If lathe has a clutch / brake this is easier. Start with tool clear of barrel and start lathe, engage half nut and shut lathe off with tool over threads, Lathe is now locked in its location with half nuts and head stock. Lay a clean white piece of paper under tool with good light above. with compound and cross feed alighn tool into thread as close as possible. Vee of tool should just match into vee of thread. Start and feed very in very slow .002 or so with compound and watch to see where chips come from. Just cleaning threads up you might get away with feeding in on crosslide but it will be a "form" cut and when to depth may cut on both sides of vee. How bad are the threads? At what area are they damaged? If not to bad a split brass nut could be made .675 X 40 TPI and threads lapped into shape with fine lapping comound. Yellow diamond or similar and slowly work it tighening nut down as needed. Work back and forth as needed rotating 1/3-1/2 turn and rotating back and forth ( think tapping a hole) and work slow and easy. clean barrel of all lapping compound before checking in the frame. You would have to single point the thread in the lathe with a boring bar to make the nut