I have a very nice 1898 Krag (Springfield) sporter. Stock has been cut down, Receiver sight, non-mil front sight. No markings of any type on the barrel. One round of 30/40 Krag taught me not to "know" what caliber a rifle is in. Heavy recoil and the case was split with almost no neck left. The sholder and neck had blown out. I pulled a chamber cast and this is what I found. 30/40 Krag rimmed base, 0.478" dia. just forward of the rim, 2.93" from base to neck, with a body of 1.925". Still .308 caliber. This cartridge is longer than a 30/06 and is rimmed. I have searched several books (COW, Hogan and the Boyem series)with no luck. If it is not a wildcat then what is it? Most Krags are necked down if anything. I'm hopeing that this is a known cartridge and that I can get it shooting.