Another Chinese round ID requested

[charley777]

With thanks to the attacher of the Chinese manual from which i gleaned these images...
This is a new one to me....don't know if it is related to a Russian round?
It is certainly based on neither the 76.2x545R AK-176, AK-726 naval round nor the 76.2x558R M1931, M1938 AA rounds.
Have no idea how accurate the drawings are but the case would be over 600mm.
Can anyone shed any light here? What i'm after are the dimensions of the cartridge case and info on the gun(s) that used it.
And whether Russia also used such cartridges.
Thanks, Charley

 

[charley777]

Just bumping this thread.
Does no-one know anything about this round?
It seems quite distinctive...

 

[charley777]

It looks somewhat like a US MkII or MkIIA1 case (76.2x601R) for the M5 and M7 AT gun, or M6 AFV gun.
So i am wondering if they were supplied to Russia during WW2 and subsequently found their way to China.
Pure speculation of course.
Are there any Russian ammunition manuals that are downloadable?
Thanks....Charley