BS-1 Tishina 30mm grenade launcher.
The BS-1 Tishina is a silenced Russian 30mm grenade launcher. It is developed specifically for the AKS-74U carbine. It uses a bolt-action mechanism to load blanks into the chamber alongside the 30mm grenade. Pulling the trigger ignites the blank which in turn ignites the charge on the grenade causing the grenade to be expelled from the barrel. The "tishina" name was given to it because of the fact that it is silenced (Tishina means silence in Russian) grenade launcher.