I’m far from an expert on the Pedersen but I think most Frankford Arsenal boxes were labeled simply, 20 CARTRIDGES, BALL CALIBER .276. Some of the very early boxes had the additional wording, PEDERSEN SEMI AUTO RIFLE.
Cartridges were also loaded in the UK by Kynoch.
You are correct, there are several variations. The dimensions that you gave could describe more than one. More important things would be headstamp, primer size, shoulder location and diameter, bullet type, etc.
There are also several threads on the Forum that you should search and read.
Sorry I can’t be more help.