|Place of origin||Soviet Union|
|Designer||B. M. Zorin
P. N. Korolev
Work on the use caseless rounds began in interbranch competition announced by the Ministry of Defence Industry of the USSR in 1972. The experimental series of machines under the 5.6-mm caseless cartridge designed for Izmash, received the name of AB. A feature of this scheme is the lack of sleeves in the chuck, the bullet is inside the compacted powder bombs, which the shot is almost completely consumed, and therefore there is no need to build the mechanisms necessary for the ejection of shells and reflection, facilitated by the mass of the munition. However, studies have revealed the unsatisfactory reliability of storage caseless cartridge, uneven burning compressed gunpowderbombs at low and high temperatures (powder crumbles or breaks into pieces), which leads to instability of the pressure in the bore. Also revealed problems with the obturation at a shot, which in the classical configuration cartridge provides sleeve.