The SAAMI/CIP maximum overall cartridge length is just one bit of information, allied to cartridge specs is always chamber specs and in the latter, length of throat and/or leade is specified.

What that means is that ammunition not only has to conform to SAAMI/CIP cartridge specification, but also must chamber in SAAMI/CIP specification chambers.

This explains Boydy's case above where the Lapua scenar, being a very pointed slippery bullet, can poke further into the chamber without touching the rifling whereas the point on the ogive of the S&B 140 grain bullet which is 0.300", which is much dumpier and more sharply curved in the ogive, touches the rifling well before the cartridge length exceeds spec.

OAL length is meaningless on it's own, it needs to be considered with factors like chamber cut, magazine length, length from base to calibre portion of the ogive for the particular bullet, etc.