Unidentifed "Steyr" 9x23mm machine pistol

Little is known of this mysterious submachine gun, today held at the Canadian War Museum in Ottawa, which is of probable interwar Austrian or German origin. It is built around the recoil action that is partially derived from the Steyr M.12 pistol, with a reciprocating barrel that is designed to rotate against a cam slot on the barrel extension. The barrel extension engages a set of locking lugs on the bolt face. The recoil spring runs from the bolt through into the stock; note the partial in-line section of the stock through which the spring is housed. The gun is designed to fire from an open bolt and the cocking handle is a retractable tab located just underneath the adjustable rear sight, which is likely non-reciprocating as it is a separate component from the bolt. The chambering for this weapon is for the 9x23mm Steyr cartridge, the standard Austrian pistol cartridge of the interwar era. The magazine feed is situated inside the pistol grip, a feature that was highly unusual for submachine guns of the period. The magazine of this weapon is now missing. The ejection port also appears to double as a loading gate for stripper clips, probably intended to take clips from the M.12 pistol.

A fire selector switch on the left side of the receiver is marked with the letters 'D E S', standing for 'Dauerfeuer', 'Einzelfeuer', and 'Sicherung' ('Continuous fire', 'Single fire', and 'Safety') respectively. These markings confirm that the weapon is of Germanic origin, though this could mean German, Austrian, or Swiss.

MPSteyr2

Disassembled view of the mysterious submachine gun, showing the Steyr-type barrel, bolt, and detachable buttstock.
(Small Arms Review)

Some elements of this prototype are consistent with Mauser designs of the early 1930s. For example, the detachable in-line stock that houses the recoil spring is a feature that was present on both the lMG 32 light machine gun and MP 33 submachine gun by Mauser. (The only known MP 33 is, in fact, also held by the Canadian War Museum and may have come through the same provenance as this gun.) Additionally, the barrel jacket is almost identical to a type seen on an experimental Mauser machine pistol of the 1930s known as the V 9000. Other elements of the design are clearly more derivative of the Steyr pistol, which would not be typical of Mauser, though this could perhaps be explained by the weapon being made on commission for an Austrian client who requested these traits. With these factors taken into consideration, it is the author's opinion that this submachine gun was probably built by Mauser in the late 1920s or early 1930s for Austrian trials, but was evidently not successful.

Gallery (click to enlarge)

Unidentified "Steyr" 9x23mm machine pistol

[DE] Maschinenpistole "Steyr"

Gallery (click to enlarge)

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