I'm bored on a snowy day in Ks. Pulled out the .300 BO and my Frankfort Arsenal cartridge overall length gauge.

First clamp on with the bolt in and locked. Second clamp on with a bullet held up against the rifling. Put the calipers in between and read the number. Easy right...

Overall measurement is showing 2.310.
If I haven't lost all my marbles, that is .050 thousandths longer than the SAAMI spec for this round; which is published at 2.260 max.

What am I missing here?