Because it is assholes using software to create bullshit.
The Soviets had silent grenade launchers... ironically the only firearm launched bayonettes I ever heard of was the SA80 which had an over the muzzle bayonette design that sometimes had problems with its catch and was launched from the weapon when the weapon was fired.
This is a 30mm grenade launcher with a silenced cartridge that launches the grenade... a bit like their silent 82mm mortar.
It replaced the earlier Device D 30mm grenade launcher based on a single shot pistol with a suppressed firing cartridge:
This was replaced by the Device DM which has a five shot magazine of propelling rounds but the muzzle loaded 30mm grenade is the same... so you loaded the projecting charge using the bolt action, then muzzle load the 30mm grenade... pull the trigger to launch the grenade silently then operate the bolt to reload a new propelling charge and then muzzle load a fresh grenade to fire.
Will likely move the fishing rod and bayonette grenade launcher posts to the talking bollocks thread... likely created by westerners jealous that the Soviet underbarrel grenade system is superior to the US piece of crap M203 in almost every regard.