Steyr M1912 Full Auto Handgun

This was used by the Hungarian Army.
Specifications:
Type: automatic pistol (recoil operated)
Maker: Osterreichische Waffenfabrik Steyr, 1912-1919, about 300,000 were manufactured. A number of parts were made and pistols assembled by Fegyver es Gepgyar Reszvenytarsasag, Budapest ('FGGY')
Chambering: 9x23mm Steyr, some in 9x19mm Parabellum
Length overall: 8.50in (216mm)
Barrel: 5.04in (128mm) rifled 4 groves, rh
Weight unloaded: 40.2oz (1020g)
Magazine: 8-round charger-loaded internal box
Muzzle velocity: 1115-1200 fps (360-385 m/s)

Background on this Weapon:
The Steyr-Hahn (hahn is German for hammer) pistol was first produced in 1911 with a fixed blade front sight, the model M11. It is an 8 shot top loader that is stripper fed, shooting the 9mm Steyr cartridge. The model M12 with dovetailed front sight was adapted by the Austrian Army in (surprise) 1912. The gun was produced until 1919 although it is believed that many were assembled from parts for several years thereafter. The Romanian police used the Steyr-Hahn and that version bears a Romanian Crest. The Chilean Army adopted the M11 and that model bears a crest also. About 300,000 were made in all. A few Steyr-Hahns Model M16 in full auto with extended magazines were used in WWI and by early Austrian Nazis. The Czechs were known to have converted some military issue Steyr-Hahns to full auto with a similar mechanism as the factory produced weapons but without the extended magazine. A wooden shoulder stock/holster with a cup that accepts an unaltered Steyr-Hahn's frame about the grip is occasionally seen.
The serial number typically appears in 3 places, the left frame above the trigger, and immediately above that on the left center slide. The serial number will also be on the barrel, sometimes without the trailing alphabetic suffix. Rarely the serial number will be on the grip's butt.
The grips are typically a brown stained wood with a raised crosshatch pattern. They are slid into cuts in the frame and secured with a single screw through the frame at the grip butt.
All parts show small proof stamps consisting of the initial of the person who proofed the weapon.

Design:
The design is believed to be by Karl Krnka based on earlier work by Georg Roth. I have seen no documentary evidence about the designer however. The Steyr-Hahn is a large frame semi-auto, single action pistol. The slide is retained on the frame by a keeper similar to that on the 1905 Colt. The action is that of a rotating barrel which is kept locked by the action of the bullet passing through the bore. When the bullet has left the bore, the barrel is free to rotate and unlock the slide, which recoils to the rear. It is otherwise similar to other semi-auto pistols with a recoil spring under the barrel which is retained by the keeper pin. It has an external hammer with a small spur. There is a safety on the frame, below the hammer, which locks into a notch in the slide. There is also a notch halfway along the slide which will hold the slide back with the safety. The slide will be held back after the last round is fired by the back of the cartridge follower from the magazine well. The trigger pull is transmitted via a transfer bar under the slide which pulls forward the sear, and releases the hammer.
To load, with the slide back, raise the safety into the notch in the slide to lock the slide back. Insert a stripper clip into the clip glide in the slides ejection port, and strip the cartridges into the magazine well. Cartridges can also be single loaded in this manner. To unload the magazine well, lock the slide to the rear with the safety; then push down on the magazine release above the left grip.

Other Usable Information:
A machine pistol is a handgun-style, magazine-fed and self-loading firearm, capable of fully automatic or burst fire, and normally chambered for pistol cartridges.
The term is a literal translation of Maschinenpistole, the German term for a hand-held automatic weapon.
While the dividing line between machine pistols and compact submachine guns is hard to draw, the term "submachine gun" usually refers to larger automatic firearms scaled down from that of a full-sized machine gun, while the term "machine pistol" usually refers to a weapon built up from a semi-automatic pistol design.