I don’t think any parts other than the bolt and receiver are serial numbered (serial number should start with the letters “mc”). I’m not sure what those numbers are on the shroud or cocking piece. Like I said in my first post, the 3 others I bought from Standard have matching receiver and bolt serial numbers. Also, I have an M12 in 30-06, and the bolt and receiver hav matching numbers, with random number markings on the shroud and cocking piece, but none of those markings start with “mc”, like the serial numbers.
