The barrel on my main rifle was originally threaded but was used to build my post-ban configured rifle, so I turned the threads off it. I turned off just enough that the root of the thread is faintly visible,
but has zero grip. There's a collar over that section now which is secured by loctite and a setscrew.
I'm going to de-neuter this barrel come September 13th. (Barring any unforeseen and unlikely changes in fortune.)
The plan: Rethread the section with a smaller thread, NEF series, probably 7/16ths.
I need to find the major and minor diameters and thread pitch of the NEF size in 7/16ths,
because I don't have it and it's not easy to find it even in a google search.
Does anyone have that info?
If not, I'll settle for cutting to 7/16-20.
The next phase, now that I have undersize threads on the barrel, is to drill and tap a piece of 4140 to 7/16-20, sized for a close tolerance fit. Locktite it and apply a pretty hefty amount of torque to it. Then turn that down to get my major diameter for standard 1/2-28 NEF threads and chase those threads. The A2 FH will be mounted with moderate torque and a crush or peel washer.
If anyone has dimensional specs for the NEF series threads, I could sure use them.