I slugged my first Mosin for reloading, It measured out at .312, There was a post on 7.62 that some guy had measured a few different bullets and found that the Sierra .303 cal 180 grain Spitzer bullets measured .311 out of the ten or so he pulled to check, So I went with them.
I should check my M44, It will give me something else to do other than plink away on the computer.