USER - can answer your question on whether it's a M82 or a C3. Detailed pictures are a must. You need to tell us the barrel markings. Need to see the serial number. Is the rifle imperial or metric proofed? This info along with the calibre will be on the left side of the barrel. Also if you show us the build date on the barrel it will confirm year of manufacture. It is quite possible that you have a C3 receiver repurposed to a M82 and maybe the barrel is original. C3 receiver do exist. Ron(Canadaicon)