I'd say the whole rifle needs a clean and oil, wood needs some BLO. Pic #2 here shows the bolt lug has the other proof mark, one on the barrel ring and one on the bolt lug. Both are typically smashed. Yes, the gas cylinder could have been switched during the import degreasing. Stranger things... Nice rifle. Nice history capsule. I take it the bore is about new? Have a look at the firing pin, you'll have to strip the bolt to do that. Round profile firing pins are probably best not fired. Mine didn't break but if it does it could cost the rifle.