OTs-12 Tiss

OTs-12 Tiss ("Yew Tree") (Russian:ОЦ-12 Тисс) is a Russian fully automatic compact assault rifle. It is chambered for the subsonic 9x39mm round primarily made for police forces. 
The rifle was developed in the early 1990s in TsKIB SOO of Tula designers VN Telesh and Yu.V.Lebedevym. It is basically an AKS-74U re-chambered for 9×39mm, it was designed as alternative to the AKS-74U. The TsKIB COO of Tula made several hundred of OTs-12s, which were transferred to the Interior Ministry security forces. Despite the good evaluation, the Tula Arms Plant did not establish a mass-production. They instead opted for a bullpup configuration known as OTs-14 Groza which became its successor.
The main design changes from the AKS-74U are in the bolt, barrel, muzzle-brake, and magazine. The 20-round box magazine was designed so that it would be compatible with standard current-issue ammo pouches, but a larger 25-round magazine was in early production until its cancellation.
The subsonic round showed superior penetration of cover at short and medium ranges (200–300 m) when compared to the 5.45x39mm. Still, the OTs-12 did not go into mass-production and was discontinued later that same year.