ROFSTEN submachine gun

(Author's photo via Royal Armouries Collection)

In 1944 the Royal Ordnance Factory at Fazakerley (ROF) proposed a new submachine gun to the Ordnance Board. This was known as the "ROFSTEN", but in spite of its name it had little in common with the actual Sten gun. The receiver was totally unlike the Sten's and was built from extremely well-finished machined steel. The magwell was fixed to the receiver and took the standard 32-round Sten magazines in a vertical position. The barrel was attached to the forward receiver by a screw-threaded nut and flange. The bolt was not a Sten bolt but a new type which was mounted on two spring-loaded guide rods, positioned adjacent to each other. In the rear end of the receiver, a strong spring buffer sat between the guide rods. Although there was no foregrip, an ergonomic wooden pistol grip was employed, and the buttstock was taken from the Mk.V Sten. The barrel featured a flash hider, a large front sight with No.4-type sight protectors, and a bayonet mount that took the standard No.5 sword bayonet.

The cocking system in the ROFSTEN was very unusual and can be compared, to some degree, with that of the Bergmann MP 35/I or Suomi KP/31. The cocking handle, taking the form of a retractable ring-shaped piece, protruded from the rear end of the receiver. It was attached to a wire pulley that ran underneath the bolt housing and attached to a moving slide. The slide engaged directly with the bolt, so that when the cocking ring was pulled back, the slide would pull the bolt into the rear (cocked) position. The slide and cocking ring moved independently of the bolt and did not reciprocate with it when the weapon was firing.

The 9mm ROFSTEN with No.5 bayonet affixed.

The ROFSTEN also employed a three-position fire selector switch which was located on the left side of the lower receiver. The safety mode engaged an internal plunger which slotted directly into a hole on the underside of the bolt, preventing it from moving. The bolt actually had two underside holes, one of which would line up with the plunger when the bolt was in the cocked position, and the other would line up with the plunger when the bolt was in the closed position. The other fire modes were automatic, which disabled the trigger sear, and semi-automatic.

Due to budgetary restraints, the ROFSTEN never got very far in development. ROF Fazakerley assembled only a single prototype, and as far as is known, it was never formally trialed. It was certainly never seriously considered as a competitor to the Patchett, BSA, and MCEM submachine guns that were slated to replace the Sten. A compact machine-pistol of a similar design to the ROFSTEN was also produced at ROF Fazakerley around the same time, and may have been intended as a companion weapon, but this too was only made in a single prototype.

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