Need help with rifle barrel ID

[lark63]

This came with a bunch of items I inherited.
Looking for ID of this barrel to see what it might fit.
Known facts;
Stamped 22-250 only
Has a M stamp -as shown in photo
18 on a thread pitch gauge.



Thanks for any leads.

 

[cowboybart]

At 18 TPI - I'm stumped. What is the shoulder OD? OD about .75" in front of the shoulder? Cut it off and thread it for what you want.