Dear Ralph,
I received Your e-mail. Thank You very much.
As I understood the result. The dies listed at CH4D for 11x65R and 11.15x65R LK Express really are the dies for the same cartridge 11.15x65R LK Express, but with variation in dimensions in 0.002 inch. Mentioned dies were produced as custom dies for different real customers and then included in the general list of dies. I suppose that it’s 11.15x64R is also from the same family.

I am sure if to search and carefully examine old german catalogues it is possible to find direct or indirect information about our cartridge. For example I know about cartridges 11.15x65R only with lead bullet. I have not seen any picture of that cartridge with jacketed bullet. In our forum we can find the page (posted by Lancaster) from old Tesko catalog with the table of different cartridges with JACKETED bullets, including 11 x 65mm (!) caliber. (”Kugelpatronen mit unserem Kupfernickelmantelgescose “Tesco…”)
The table:

The link:
http://forums.nitroexpress.com/showflat.php?Cat=0&Number=107196&an=0&page=1#Post107196

As I know, the stamping-marking system was more or less standatised after WWI. So it is very difficult to understand correctly the marking on old pre WWI guns. But I suppose that the caliber marking have obligatory to be on the barrels. The interior (land) (!) diameter was marked as tradition in Germany. It may be in “mm”, but old German guns were marked in another style. The system of gauge numbers was used for barrel diameters. This was largest plug gauge diameter that would fit in the bore.
My barrel was primarily marked as 67/49 (later restamped as 10.7 mm). I know, that barrels for 11.15 mm were marked by “bigger” gauge number as 62/78. Here it is example from our forum.

http://forums.nitroexpress.com/showflat.php?Cat=0&Number=70291&an=0&page=0#Post70291

You will see as “PATR.11,15-65.4.SP.17.7 BL” as “62/78”.
I suppose that “4.S.P.17.7BL.” mean 4 Swartz Pulver 17.7. Blei Geschosse (Black powder, Lead bullet)

Please try to look carefully Your barrel and try to find the caliber mark. It may be 67/49 or 67,49 or simply 67 49 (by space). Of course it may be in “mm” too.

I will send e-mail too.

Oleg