The Sten Gun Mk.2 with silencer is effectively the same as the Sten Gun Mk.2, with the exception that it slows the muzzle velocity to subsonic speeds and slightly reduces the rate of fire of the weapon, while greatly reducing the noise that the gun puts out. To pervent the gun from overheating, usually fired one round at a time, like with a semi-auto gun.
Sten Gun Mk.2 on Wikipedia