Thank you for your comments guys! Very helpful, so this is not a problem and could have been due to the "original" size of the fired brass being slightly different.

I should mention that I have found it hard to distinguish between brass fired once in my three 300 WM rifles. All seem to have nearly the same size which is Minimum chamber + 0.000 to Minmum Chaber + 0.002 inch (again measured using Redding tool).

I have been thinking buying the Redding competition dies set (the bushing model) but I have so far resisted the temptation wink Would that improve my accuracy by any discernible measure? I make loads for hunting and general shooting at the range, not for competition.

Thanks again smile