I have a Mauser sporter which has no manufacturers markings. At some time in it's life it was drilled and tapped for a scope, and was that way when I acquired it. It is marked "8 mm" and has the number 37.51 on both the barrel and receiver. It chambers and fires 8x57 mm JS ammo, but I have only used the low powered American loadings. I'm not sure if has a .318 or .323 bore. It has a nitro proof mark from Vienna, Austria.

The rifle has double set triggers, a shotgun-type trigger guard, and is extensively engraved. The stock has a cheek piece. The front swivel is mounted on the barrel. Attached are a variety of photos of the rifle. Does anyone have any idea who made it or in what year? Is it likely a .318 or .323 bore? This and any other information anyone can provide would be very much appreciated.