Dear Ralph,
Sorry for delay.
In the beginning of the XX century weapon and cartridges were developed very fast. Other machine-technologies developed too. The development was also complicated due to introduction of smokeless powders. Smokeless powder was introduced by different ways. It was possible to put a small quantity of nitro powder into blackpowder cartridge. In this case the nitro-cartridge will be almost the same powerful as blackpowder cartridge. It is better try to make a new cartridge for nitropowder. It will be much more powerful. That new cartridges may be created in modern style in bottleneck brass and smaller caliber or it may be old fashioned with straight brass and the same caliber. I suppose, all that tendencies developed parallel, but during relatively shot period of time (some years).

I suppose, that our cartridge (11x65R Forgotten) was created in that short period and produced for a short time about 10 years, not longer. I suppose, it has not the blackpowder predecessor with the same caliber and dimensions. In opposite case that cartridge life would be longer and it would not been forgotten.

Ralph, You mentioned a very good example. It is cartridge 9.3x72R also called as “360 Express BlackPowder & Nitro”. Let’s compare it with the next generation cartridge 9.3x74R. It is an example when newly created nitro-cartridge has similar, but different dimensions. We can find a specific logical construction in that difference.

What is the main? The main is safety! What is dangerous? It is dangerous to put nitro-cartridge into the blackpowder weapon (chamber). What is the easiest way to prevent it? The easiest way is to create nitro-cartridge with a little bigger brass and smaller caliber of bullet. The cartridge 9,3x74R have dimentions similar as 9,3x72R, but the base diameter of brass is bigger, brass is longer and the bullet diameter is smaller.

Base – 11.83---10.76
Length – 74.09--- 71.76
Caliber- 9.25--- 9.51
All data is in “mm” from www.municion.org

Taken in account the mentioned logic, I suppose that the blackpowder predecessor of 11x65R Forgotten (our cartridge) was 11.15x65R LK. Brass became a little thicker, but bullet became jacketed and a little slimmer. The diameter of lead bullet in 11.15x65R LK is 11.31mm (municion.org).

Ralph, it is very good, that Your barrels have the same caliber mark as my 67/49. I have already wrote in my previous post about “bigger” caliber marks 62/78 on the barrel for 11.15x65 cartridge. The example (posted by kcordell) we can see at our forum. It is Sauer&Sohn drilling.
It is another photo with better quality. See second photo from the top.

http://forums.nitroexpress.com/showflat.php?Cat=0&Number=102759&an=0&page=1#Post102759

I have new information too. One my pen friend from other forum from Russia has old Collath drilling. His drilling marked as 11mm x 65 and at the same time have gauge marking 67,49 (as my and Your drillings). See photo. It not very god, but may be zoomed, click please.

What does it mean? It mean that cartridges 11.15x65R LK and 11x65R Forgotten is not the same cartridges (sorry, as a first step of evidence - not cartridges with the same diameter of bullet). The second step is chambers in our drillings.

Sincerely Yours
Oleg

P.S. I will try to write something for WBD too, but a little later.