About the proofmarks: The CROWN - crown/N proofmarks indicate proof using the "4000 atm proof powder" according to the proof rule of July 23,1893. 8.7 is the bore (not groove or bullet) diameter as measured by the proofhouse. 6,28 = June 1928 is the proofdate, while 316 is a proofhouse ledger number, gun # 316 proofed 6,28. The stamping of the ledger number shows your rifle being proofed by the Zella - Mehlis proofhouse, so the barrel and gun were probably made there, not in Suhl.