I don't know if these will be useful to you, but here are some images from the ol' 1939 Stoeger.

Stoeger billed themselves as the 'sole importer' of 'Genuine Mauser' products to the United States at the time.

These are fresh Mauser actions for builders. Those marked with an asterisk (.30-'06,.280 Ross, .318 Westley Richards, .350 Rigby, .375 H&H, .404 Jefferey, .416 Rigby) differ from the others, having a hinged bottom plate with button release (rather than lever release), but the only mention of magazine length is in the first paragraph; "Each Mauser action is made expressly for the cartridge it is to use, particular attention being placed on size of magazine and the head of the bolt".

This .280 (No. 628A) is described as being "built on the famous Mauser Magnum actions":