Russian Degtyaryov Plant has published on their social media pages а photo depicting their new rifle called KSO18 (КСО18). According to the company, this is their newest balanced action rifle which they will soon officially introduce to the Russian civilian market. This rifle is apparently based on Degtyaryov Plant’s AEK-971 which in 2018 was adopted by the Russian military as A-545 (GRAU index 6P67 (6П67)) along with its 7.62x39mm sibling, the AEK-973 (A-762, 6P68) and AK-12/AK-15 rifles.
Balanced action firearms utilize a counterweight that has the same or similar mass as the bolt carrier group but moves in the opposite direction thus compensating the shocks generated by the reciprocating mass and the impacts of the BCG on the receiver. Normally, in such systems, the counterweight is linked to the BCG via a gear to allow synchronizing the motion of two reciprocating parts. Also, in this weapon, the counterweight is kind of a secondary piston and it’s not only driven by the linkage with the BCG but it’s also pushed by the gasses tapped from the barrel. The advantage gained from the balanced action mechanism is the higher controllability of the weapon system, especially in full auto mode. Now, for a semi-auto civilian rifle, this feature is not that important. However, competition shooters often shoot their weapons at extremely high rates comparable to full auto and for them, having a balanced action rifle may actually be a benefit allowing to do faster and more accurate follow up shots. Here are some drawings of Degtyaryov Plant’s balanced action mechanism from the company’s patents.
The main or rather the only competitor of KSO18 on the Russian civilian market will be Kalashnikov Concern’s SR1 which is also a balanced action rifle.