The Royal Small Arms Factory built the first suppressed Sten submachine gun following a request from the Special Operations Executive — Britain’s World War II commando headquarters — for a weapon for clandestine missions demanding lots of firepower.
Early experiments with suppressing the Thompson submachine gun — the weapon British commandos preferred earlier in the war — proved to be a failure. The Royal Small Arms Factory took the Sten Mk. II and incorporated an integral suppressor — one of the first-ever instances of a submachine gun with built-in silencing. The War Ministry designated the gun the “Carbine, m/c Sten, 9mm Mk2(S).”
The “S” stood for “special purpose.”
The Mk. II(S)’s barrel was ported and surrounded by a jacket filled with baffles to expand and dissipate the propellant gasses. To ensure reliable cycling, engineers lightened the weapon’s bolt and removed several coils from the recoil spring. The suppressor lowered the weapon’s muzzle velocity from around 365 meters per second down to 300 meters per second — well below the speed of sound.
With sustained or repeated firing, the ported barrel and suppressor heated up rapidly. The designers combated this by issuing a canvas barrel-cover to insulate the user’s hand. Still, sustained full-auto fire of just one magazine would effectively wear out the baffles and burn out the suppressor.
The first operational Mk. II(S)s saw combat in Europe in 1943 in the hands of frontline agents of the SOE. The guns also saw action in the Far East and with special reconnaissance parties.
It seems that a silenced Sten based on the aborted Mk. IV prototypes — the Mk. IVA(S) — also existed. The War Ministry never adopted the Mk. IV in any variant, instead taking the more-robust Mk. V. With the operational success of the Mk. II(S), engineers also developed the Mk. V into a suppressed Mk. VI(S) in 1944.
The Mk. VI(S) combined the stock furniture and receiver of the Mk. V with the canvas insulating-shroud of the Mk. II(S). The Mk. VI’s suppressor was shorter than the earlier Mk. II(S)’s, but was more difficult to disassemble and service.
Otto Skorzeny, a German S.S. officer who took part in the rescue of deposed Italian leader Benito Mussolini in 1943, went to great lengths to acquire a suppressed Sten. “What splendid possibilities the use of these silencers offered,” he noted when he finally obtained one. “What losses they might save and what dangers they might avert! How wonderful, in case of an unexpected meeting with an enemy detachment, to be able to fire without the reports attracting the attention of other enemy groups!”
The Germans captured a number of Mk. II(S) during the war and designated them “MP 751(e).”
The British produced 5,776 Mk. II(S)s and 24,824 Mk. VI(S)s during the war. While the British Army officially declared the Mk. II(S) obsolete in April 1945, the weapon remained in service for several more decades. The British Army deployed them in the counterinsurgency operations in Malaya and Kenya during the 1960s.
A suppressed version of the Sterling submachine gun, the L34A1, formally replaced the suppressed Stens in 1966, but commando units such as the Special Air Service and Special Boat Service held onto their suppressed Stens for many years.
They weren’t alone. The Australian SAS used both the Mk. II(S) and Mk. VI in Vietnam in the 1960s. U.S. units of the Military Assistance Command Vietnam, Special Operations Group also favored suppressed Stens for clandestine operations such as long-range reconnaissance, prisoner-snatches and assassinations. Operators liked the Mk. II(S) because it could be easily disassembled and compactly stored in a rucksack.
The British Army’s own special forces finally replaced their suppressed Stens with suppressed MP5s in the 1980s.
This story originally appeared at Historical Firearms.
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