Wonder of wonders..I got my new eyeglasses yesterday evening and there it was, right in front of my nose. FC
If the case is brass, it probably is Federal, mfg in the US and some European countries.
If the case is steel, it probably came from Pri Partizan, Yugoslavia.
Note: My Yugo made SKS doesn't like the commercial brass stuff. The extraction is so violant that sometimes the head of the case is pulled off.