Ian - since you own the original drawing, could you perchance publish on this Forum some of the key measurements to the cartridge. I enhanced the photo quite a bit from how it appears on my screen from the Forum, but the measurements are still not legible either in the Data Block at the bottom left, or from the drawings themselves. They are pretty important to finding out if any specimen of this cartridge exists.
Woodin Lab, could not tell of hand, if one is in the collection due to a lack of any usable information on the cartridge specs.
Thank you for any help you can give us in that regard.
OAL of cartridge, bullet diameter, case mouth diameter, base diameter, head diameter and cartridge case length would all be highly useful for possible future identification. It is recognized that the case shape itself is fairly unusual, but evidently not completely adequate for ID.