Surely 30-06 is the longer of the 2 cartridges, it having a 63mm case as opposed to the 7.92mm's 57mm case?
Printable View
There is clearly no practical advantage from enlarging the loading aperture to handle either the .30-06 or 8x57 cartridges. I think some keen Danish armorer got the inspiration and was allowed to run with it.
Actions from these were for sale a few years back. They had been refitted with M1917 bolts for the rimless 7.92 and I suspect the barrels had been rebored from .303.
The Red Chinese converted M1917 rifles captured from the Nationalist forces to 8mm because they had facilities to mass produce 8mm ammo.
Some Scandinavian countries used an 8mm long range Browning MG that fired a longer cased 8mm cartridge.
Usually the bullet was seated deeply to maintain the same OAL as the .30/96 but there may have been some with greater OAL.
MG crews were often armed with Mauser rifles converted to use the special MG cartridge.