Quick search and I found this link. I cant read russian but look like it has some drawings and such. Double click on the manual pictures and should bring the picture to full screen. At least it works on my PC for easier reading.
I guess I found part of the answer to my earlier question:
One round Link for the Soviet 20 mm for ShVAK / B-20 weighs 8.288 ounces.
Source is the Rechlin test of a Lavochkin La-5FN which lists the weight of the ammunition.