Specs I have for a minimum .440 3" chamber call for .463" diameter at junction with cone & .005" per inch taper. This would thus give a .015" enlargemet over the 3" or .478 at rear. This is of course Minimum. Maximum cartridge is only about .001" less than the minimum chamber.If your measurement is accurate your chamber would appear to be .004" undersize definitely enough to cause some problems.


Miller/TN
I Didn't Say Everything I Said, Yogi Berra