MANUFACTURER – Royal Ordnance Factory, Theale, England.
STATUS – Obsolete
SERVICE – British Military
The successful acceptance of the Mk V Sten helped initiate an examination for a suppressed version of the new weapon. Problems existed in the simple adoption of the suppressor from the Sten Mk II(S) to the Mark V design. The sight being mounted on the barrel of the Mk V (On the Mk II it is at the front of the receiver) required a locating stud to be on the barrel nut so that it always located in the same position when the weapon was stripped for cleaning. That stud prevented the suppressor from the Mk II from simply being screwed on. Additionally, with a suppressor on the weapon, the barrel mounted front sight was missing.
For the initial 24 suppressed Mark V guns produced, they were fitted with a front sight held by a band clamp (the “Foresight band”). The weapons were then fitted with a suppressor that had been originally used in the Sten Mk II(S) trials but not adopted. The new suppressed test weapons were designated the Sten Mk V(S) and only the original maximum of 24 test weapons using the Foresight Band were ever produced.
The production model of the new suppressed Sten was referred to as the Mk 6. It had the front sight dovetailed into the front of the receiver, behind where the suppressor would attach. The suppressor itself was made up of two tubes, the rear being the 72.1 cc (4.4 cubic inches) internal volume expansion chamber and the front the baffle stack. The rear expansion chamber was 12 cm (4.75 in) long and surrounded the short 9.5 cm (3.74 in) barrel. In front of the chamber of the barrel were drilled six 2.4 mm (0.10 in) into the bore. These holes helped lower the muzzle velocity of standard (Mk2Z) ammunition to below the speed of sound. The holes also bled off propellant gases into the first expansion chamber where they were partially cooled by expanding to fill the area. The front of the expansion chamber was closed off by a disk that was threaded onto the muzzle of the barrel. The front disk has a number of holes surrounding the muzzle of the barrel to allow the propellant gases to bleed into the front tube of the suppressor.
A portion on the outside of the front of the expansion tube is threaded. An internally threaded barrel sleeve connects the front of the expansion chamber to the threaded rear portion of the baffle stack tube. The baffle stack tube has an internal volume of 180.3 cc (11 cubic inches). In front of a small expansion chamber at the rear of the baffle stack tube is a stack of 15 brass mesh disks held in place by a cup-shaped baffle. There is an additional stack of 28 cup-shaped baffles spaced out along the body of the tube, each baffle having an 11mm (0.44 in) diameter hole in its center. At the front of the stack, near the muzzle of the suppressor, is an additional 15 brass mesh disks. These are held in place by another cup-shaped baffle. The muzzle of the suppressor has a front plug that is brazed in place as well as secured with a small screw.
The outside of the suppressor body had a section covered with about 4.9 m (16 feet) of asbestos string, which was itself covered in insulating tape. Over the string and tape was secured a canvas sleeve the same as that used on the Sten Mk II(S). In the final production of the Mk 6 (S) weapon, over 24,800 units were produced. They remained in service until the early 1970s.
