Looked down the bore and very dark BUT its a four-groove.

Now, under long-term barrel soaking with fresh Hoppes, after six hour with send a FRESH bore brush down bore and see what develops.

Took some photos before the soaking, will post later.

Did the same with a 17 Enfield and that took five days.

Sporterized MIL Stock has a "R" stamped on the flat surface under the front ring, nothing else.

No rebuild stamp after WWII.