The 40.8mm Taubin Automatic Mortar (clip? or tray? feed) was developed by Yakov Taubin mainly during the years of 1934-1938 and used a very short cartridge case crimped to the base of the grenade body. It appears use by the Red Army was limited to the Winter War against Finland (1939-1940). By 1940 the AG-2 fell out of favor due to mechanical issues, accuracy issues and political favoring of traditional mortar (single shot) development.
It is noted that Yakov Taubin was a successful weapons engineer. At the end of 1940, he was awarded the Order of Lenin for the development of the MP-6 aviation automatic cannon. In May 1941, he was arrested and charged with involvement in a military conspiracy and was executed on 28 October 1941. This was a common fate for many engineers, military officers etc. during this time frame.
Below is an excellent drawing by Evgeny Kravchenko aka “Jhonni” showing the 40.8mm grenade cartridge for the AG-2:
Below is a photo showing the a complete Taubin 40.8mm grenade cartridge (left) and the grenade projectile separated from the cartridge case (right):
All of the information shown above was collected from various Russian websites and I used Google Translate for interpretation of the Russian text which means there is the possibility for errors in the information presented above.
In addition it is extremely unlikely that anyone in the USA or Europe has an example of the Taubin 40.8mm grenade cartridge in their collection, but I believe this is an important historical early effort in the development of grenade cartridges that are so common now days.
Corrections, additional info, discussion are most welcomed.