I am following an advertisement for a drilling rifle which shows the rifle barrel to be chambered for the 10,75 X 65R. Now I understand there is a Grundig cartridge as well as a Collath cartridge, both wearing the same numbers. Can anyone tell anything about either of these cartrdiges and the difference between them?

The two cartridges are only the same in bullet diamension. The base measurements are different and the Collath round is made on a slightly necked 11.2 x 65R parent case. I have more details if you want , dont have time to type it all out at present .

The Grundig predates the Collath , circa 1900 against c.1905.