The STEN Mk.6 was developed in 1945 to produce a firearm. It is generally similar to the Mk. 5, the trigger mechanism remaining unaltered and the same design of breech block and return spring being used. The same pistol grip and butt stock are made from wood. The same main casing is used but it has a dovetail slot for the fitting of a foresight as used on the STEN Mk. 2.
It is designed for use as a silenced special purpose weapon as the Mk. 2(S) but is an adaption of the Mk. 5. The silencer, which is incorporated with the barrel. It functions in principle the same as that on the Mk. 2(S) but differs slightly in constructional details. It’s also covered with canvas heat shield laced onto the jacket as a hand grip over an insulation. It was used by British and Australia Special Forces and Commando Companies.

1. Enhanced welding process, to prevent the receiver from breaking
2. Blued surface process
3. Short traveling breech block provides better efficiency of gas
4. Wooden stock and grip are made of beech
5. Brass stock butt plate
6. Various markings on the gun:
a. M/78 of magazine housing marking refers to its maker of "Elkington & Son".
b. The serial numbers of magazine housing matches the one on suppressor cap.
c. Maker markings inside the brass butt plate
8. Steel structure, exclude the barrel base and breech block.