FrankenMauser, SAAMI's specs for a .270 case length is 2.520" to 2.540". I've had no problems full length sizing .30-06 fired cases to make .270 cases that long. .30-06 case length's 2.474" to 2.494" and the shortest one can grow 50 thousands easily when full length sized in a .270 die.
A case even .010" shorter than SAAMI specs in either round's SAAMI spec'd chamber is not a problem anyway.
We might as well claim that all cartridges based on a rimless bottleneck case with ~.474" rim diameter should be traced back to the 7x57 Mauser round as it's probably the first one of that ilk. All the others just used a longer case with different body taper, shoulder diameters/angles with different neck lengths and mouth diameters for different bullet diameters.
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