I have a sporterized m43 Mauser. The chamber is still original as it had no problems with the Remington cor-lokt 8mm Mauser ammo. I need to measure the bore diameter. I put a slug from one of the cor-lokt rounds in the muzzle (the same way you would with a mosin nagant) and it stopped half way. Does that usually mean it's a .318 barrel? If I slug the barrel, can I use a pulled slug from a 7.62x54r round (7.92mm bullet diameter) or do I have to use a lead ball? If I use a lead ball, what size do I need?