Steve: I agree but I wanted to try and at least narrow down what I might have. I have measured again and came up with a repeatable .251 as the bore so I believe it is a 25 CALIBER (.250), A 25/06 WOULD HAVE ALLOWED A 6.5X55 TO CHAMBER completely A 257 ROBERTS would not. A .250 Savage has a bore dimeter the same and also would have failed to chamber. So tomorrow I am going to feed function test a 257R and a 250S.