Russian designers have developed a new method for single-shot firing from automatic weapons, which should increase the practical rate of fire and reduce barrel oscillation during shooting. The new operating scheme for the mechanisms was proposed by the Joint Stock Company "KBP Instrument Design Bureau named after Academician A. G. Shipunov" – the development received a patent from the Russian Federation.
The new approach differs from traditional schemes for controlling single-shot mode. The designers changed the interaction of the trigger mechanism, hammer, and bolt group to speed up the weapon's preparation for the next shot and make control more convenient for the shooter.
According to the development description, after the weapon is switched to single-shot mode and the trigger is pulled, the hammer disengages from the sear. After the shot, the bolt carrier, along with the bolt, begins to move backward under the action of powder gas energy. At the same time, the hammer retainer disengages, and the hammer and bolt group begin to move independently of each other.
During recoil, the spent cartridge case is ejected, after which the bolt carrier returns forward under the action of the return mechanism and mainsprings. The bolt picks up the next cartridge and chambers it, and the hammer is fixed in the ready position for the next single shot.
The main difference of the new scheme is the changed operation of the single-shot sear. After the reloading cycle is completed, the hammer is automatically held by the mechanism until the trigger is released. After that, the weapon is again ready for a single shot.