Thanks. If my research and speculation is correct it was originally chambered for 7x57 and I wish it still was. The .243 is a bit short for the action length and does not chamber as smoothly as the longer round probably would. Might just have to pull the barrel and send it to the barrel maker and have a 7x57 profiled to match. But,... As is it shoots the 100gr BTSP into 1/2 MOA. Kind of tough to pull it apart when it ain't broke.