Threading was for bullet shredder (blanks fired wooden bullets). Not original, but added while still in service. Yes, ugly plastic cap is correct as issued, but the AG42 flash suppressor also fits, and there are after maker steel ones that look better. Doesn’t add much value, as they aren’t that hard to get. The ‘96 Mauser is a nice rifle. What does your stock plate say?
There are three sections.
Torped Overslag 0 Str (With umlaut over O)
6,51 followed by 23456789 over 6,48 followed by 7890 (there is a stamp mark a base of the 0)
1 over 23
The full name is Carl Gustafs Stade Gevarfaktori 1915