Thanks. I thought it would be a more common model. Need to track down a bolt and I want to see if I can get a new barrel turned for it with the heavy Mk. II** profile since I found a print of one. I had been think about that before running across this receiver. Problem will be getting someone to thread it but I'm in no rush. I think what scares people away from cutting the thread is that it's a buttress thread rather than common v form thread.