Weird Magazines, Vol. I: The Kottas Magazine System

Nathaniel F
by Nathaniel F

The truly high capacity magazine has been a dream that firearms inventors throughout the world and time have endlessly pursued. One of the crazier attempts to improve the capacity of the Steyr-Hahn 1912 handgun was a system designed by Arthur Kottas. Over at Historical Firearms, Matt elaborates about this unusual and eyebrow-raising magazine design:

The patent drawing above shows an unusual magazine system developed by the retired Austrian army officerArthur Kottas. Kottas’ magazine combines a looped channel within the stock with a horizontal feed which turned cartridges as they entered the action to be chambered. Kottas first patented his design in Austria in August 1918, before the end of the war, and later patenting it in the US in 1921.

The pistol Kottas uses to demonstrate his magazine design is a Steyr M1912 semi-automatic pistol, itself designed by Karel Krnka. The conventional M1912 was loaded with stripper clips into an 8-round box magazine in the pistol’s grip. The M1912 was a robust and reliable early pistol design and ran well in the field, its stripper clip feed system being its primary drawback.


Steyr M1912 with an 8-round stripper clip ( source)

While a fully-automatic capable variant of the M1912 with an extended 16-round magazine was developed Kottas’system would have potentially offered capacity for approximately 60 rounds. Kottas’ magazine system is complex and convoluted using a steel band to pull cartridges through the magazine into the pistol’s action.

From Kottas’ patent it is difficult to ascertain exactly how the system works however, from the patent’s explanation we learn that the ammunition is loaded in the usual manner with a stripper clip from the top of the receiver where a ‘turning member’ then turns the cartridges 90 degrees and into what Kottas called a ‘loop’ (a single stack quadrangular channeled magazine) aligned transversely and as the weapon fired the ammunition was turned by a pair of spiralled feed lips (see fig.2 & 3 on the patent drawing) as they entered the action aligning it with the breech. Rather than a follower and magazine spring Kottas employed a wound ratchet system that pulled a steel ‘conveyor’ band which ran the length of the loop and pulled cartridges towards the action. The conveyor band had four dummy cartridges at the end which acted as a follower (seen in the grip in the patent drawings) these were also intended to act as a slide hold open device.


Kottas’ patent drawing of his system’s magazine ‘loop’ ( source)

The diagram above shows a cross-section of the butt of Kottas’ design showing a ratchet device attached to a crank to pull the cartridge conveyor back along the channel and apply tension to the steel loop. The patent and drawings are unclear on just how the action then pulls the conveyor band back through the magazine to feed the ammunition up into the action. It explains that the second disc at the base of the stock’s grip is is attached by a pawl to the pistol’s slide. During firing when the slide reciprocates the pawl is actuated pushing the cog-like wheel which in turn acts upon a coil spring to maintain the tension on the loop pulling cartridges up to the action. Another interesting feature was that the conveyor band was numbered to indicate how many rounds were left in the magazine. This could apparently be read as the conveyor passed through the crank at the top of the stock.

Somewhat surprisingly, Kottas’ patent has been referenced several times by major firearms manufacturers patenting ideas in the same vein. Colt, Fabrique Nationale, and Taurus all reference the Kottas patent, but also John Hill who designed a transverse magazine that we’ll take a look at later, and even United Shoe Machinery Corp, who referenced it for a magazine designed for the AN/M2 machine gun.

Nathaniel F
Nathaniel F

Nathaniel is a history enthusiast and firearms hobbyist whose primary interest lies in military small arms technological developments beginning with the smokeless powder era. He can be reached via email at

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  • Kivaari Kivaari on Oct 27, 2015

    This isn't about this. I was lucky to handle and shoot the Greer MFG (Mollola, OR.) .22-45 conversion kit. It comes with a special magazine having the ejector on the magazine. One can convert a 1911 to 22 by changing just the barrel and magazine. It has a clever offset bore. It's been on the latest patents list for the 1911. I'm surprised it hasn't been picked up by a big gun company.

  • Fruitbat44 Fruitbat44 on Oct 28, 2015

    Well, that's definitely thinking outside of the box . . .