One of the original eight contenders in the Abakan trials, the AEK-978 was designed by P.A. Pikinsky. Very little is known about its performance during the tests, although it is known that the AEK-978 made it through the first and second stages. The AEK-978 was no longer present in the final stage of the trials, and it is likely that the AEK-978 was either eliminated due to it not meeting certain requirements or, more likely, that it was pulled out at the last minute.
The AEK-978 is an assault rifle that used the BARS system, or the Balanced Automatics Recoil System. The principle of the system is that when fired, mass from the negative effects of recoil is shifted towards the muzzle as the bolt and bolt carrier are reciprocating; this supposedly helped to reduce recoil and allow for automatic fire to be more viable and practical. The AEK-978's action predated the weapon itself; it was designed in the mid-1960s by Peter Tkachev, famous for his experimental AO-63 double-barreled assault rifle. While the AEK-978 faded into history, Tkachev's action did not; as the years passed, a recoil-reducing system of this type was found to be more viable over the long run, and the BARS system found itself in the AK-107 and 108 assault rifles.