John,
Actually, they didn't stop making sporting guns until close to the end of the war ; any guns proofed under the 1939 proof law were " Nazi proofed"( from about 1940-1945). If you post photos of all the markings on the gun, including those under the barrel, we can likely provide additional info. Remo was the "house brand" for Gebruder Rempert( Rempert Brothers)( sp?).