The 9x39mm cartridge was introduced in the final days of the Soviet Union as a subsonic round intended specifically for suppressed weapons. The first weapons developed for it were the AS Val and VSS Vintorez. These were followed in the early 1990s by the OTs-14 "Groza", developed by Valery Tells and Yuri Lebedev at Tula. The concept was for a modular multi-purpose rifle which could be assembled on a mission-by-mission basis by special forces or police troops as required. The complete load out included a short barrel with vertical front grip, a longer barrel, an under barrel grenade launcher, and a telescopic sight. The base gun was an AKS-74U ("Krinkov") converted to 9x39mm. Only a few hundred were ever made, all of them converted from AKS-74U rifles rather than being built from scratch.

The Groza is an exotic and highly touted rifle in the west because it is extremely rare, but it was not really well liked by those who actually used it. It cannot be fired left-handed, it blows a lot of gas into the shooter's face when used suppressed, and its controls are rather awkward to use. the lofty original plan was to produce it in 9x39 for Spetznaz, 5.45 for the Russian Army, and 5.56mm NATO and 7.62x39mm for export sales. In fact, only the 9x39mm version was made and production took place only in 1994 and 1995.

Many thanks to the Royal Armouries for allowing me to film and disassemble this rifle! The NFC collection there - perhaps the best military small arms collection in Western Europe - is available by appointment to researchers:
https://royalarmouries.org/research/national-firearms-centre/

You can browse the various Armouries collections online here:
https://royalarmouries.org/collection/