Experimental STENs

The STEN Mk.IV was derived from the STEN Mk.II. It was designed in 1943 especially for paratroopers. Two variants existed. The Mk.IVA had a very large trigger guard for arctic mittens and a retractable shoulder stock. It was 27.2 inches long, whereas the Mk.I was 35.2 inches and the Mk.II and III were 30 inches long. It was considered uncomfortable to fire and rejected during trials.


The Mk.IVB was the second variant of the STEN Mk.IV. The Mk.IVB was designed for firing with one hand; the pistol grip was further towards the magazine and the overall balance of the weapon was better. The trigger guard and grip were redesigned. Collapsed, it was 24.2 inches. Both models had 3.85-inch barrels.

A few wooden-stocked STENs were prototyped. A STEN Mk.II with an SMLE rifle stock was prototyped, but nothing became of it due to high production costs. A wooden-bodied STEN Mk.III with bayonet fittings was prototyped but never mass produced for the same reasons. Probably the most unusual wooden STEN was a Mk.III prototype with an entirely wooden body. The pistol grip and trigger were directly below the magazine feed and the cocking lever was relocated to the top of the weapon. The stock was raised. The exact reason for the creation of this STEN is unknown, but it was probably an experiment in weapon handling and comfort.
A Mk.II STEN with an SMLE-pattern stock.

A Mk.III STEN with a Lanchester-style body and bayonet.

A Mk.III STEN with an experimental wooden body.

A special STEN Mk.II was designed for parachutists. It was intended to be used whilst descending with a parachute. It was very cheap to produce but not very comfortable to fire. It was never fielded in large numbers.

A Mk.II STEN with a pistol grip.
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