20 TPI threads on Rolling Block?

[KenH]

When you say "Vee threads", do you mean a standard 60⁰ thread? What TPI? Notice the photo above is about 20 TPI, but isn't Vee, nor is it a true square thread like the 12 TPI of most Rolling Blocks. Perhaps more like a ACME thread? I didn't measure the degree since I didn't need to cut any threads of it. Just had it apart for cleaning and took photo.

[M-Tecs]

Most V threads are 60 degree except for the 55 degree Withworth. https://www.practicalmachinist.com/v...97/index3.html

Firearm barrels with square threads are shallow square threads

The threads on the pictured barrel shank appear to be damaged. Whatever they are they are not acme or square. Hopefully the threads in the action are better. If not they will need to be recut.

Good overview on threads here http://www.nashua.edu/paradisem1/Mac...Thread_09A.pdf

[KenH]

Thanks for the two links. I've downloaded the pdf file to my library. That first link is really interesting - difference between US inch and Enfield inch. If course "everybody" knows the Enfield inch only applies to measures below 2 inches {grinning}