The Mann Pistol Model 1920/1921 in .25 ACP

In the 1920s the worldwide gun market was saturated with small, lightweight vest pocket pistols. What could an inventor do to find a niche for his new product? The answer was simple: make the gun lighter and smaller than its competitors. But unfortunately a blow-back operated gun is limited by the weight of the breech block or slide which is necessary to keep the gun closed when firing. So Fritz Mann had to innovate, but let us start at the beginning.

The Fritz Mann Feinmaschinen – Waffen – und Werkzeugfabrik (Machinery, Guns and Tools Factory) was founded 1896 in Suhlerneundorf, Thuringia. Later, in 1925, the company operated under the name of Fritz Mann Maschinenfabrik Suhl-Neundorf. The Mann family, the brothers Fritz and Otto Mann and one of Fritz’s sons Willi, were talented inventors and dealt not only with guns but also with other machinery: ski bindings, buzz saws, two-stroke engines, and crash-helmets. However, by the late 1930s the Manns were focused on other things besides their gun and machinery business, and in 1938 the company was liquidated.

What are the innovations of the .25 ACP Mann Pistol? It is simple physics that you need a certain mass of breech block in a blow-back operated gun. If you do not want to use a mechanical breech locking mechanism, you must slow the extraction of the empty case to control the point in time when the gun opens. Fritz Mann chose a circular chamber groove. Here the pressure of the discharged cartridge, for a short moment, forces the brass of the cartridge case to flow into the groove and thereby delays the opening of the breech.  This groove allowed for the elimination of a heavy slide to contain the breech block.  Instead, the breech block, or bolt, screws into the knob at the rear of the gun, as does the recoil spring guide rod.  The recoil spring is located above the barrel.

However there are a lot of variables which can affect the mechanism, including tolerances and roughness of the chamber, fouling, thickness and material of the case, and pressure fluctuations due to different loads – all influences which could not be controlled by the gun manufacturer. But somehow it worked and Fritz Mann was able to reduce the weight of the breech block by half. He also claimed a Mann pistol fired several hundred rounds without malfunctioning.  The groove is about 3 mm wide and 0.1 mm deep, and is beveled so there are no sharp edges.   Despite the beveling, in his DWJ article Benedikt Rieger reports on a Mann pistol with severe damage due to a cartridge case having ruptured at the groove.

The barrel retention method was very innovative (see figure 2). It made it very easy to disassemble the barrel for cleaning purposes. A 4 mm caliber barrel for indoor training ammunition was available. Additionally Peter Dannecker reports that a 150mm barrel was available for target shooting. Other than an advertisement in a Waffenschmied journal in 1920 there is no other proof of the existence of such a barrel--no reference sample is known.

Fritz Mann’s safety only disengages the trigger bar--there was insufficient space in his design for a safety that would lock the firing pin.  There is no disconnector on the Mann pistol

The Mann pistols Model 1920 and Model 1921 have a loaded chamber indicator on the left side of the gun. With a cartridge in the chamber, a pin on the exterior of the ejector, protrudes through the frame. If the manual safety is in the ‘Safe’ position the pin protrudes behind it and makes it more difficult to move to the ‘Fire’ position.  If the manual safety is in the ‘Fire’ position, the pin can be felt to verify that the chamber is loaded. The Model 1920 has an additional loaded chamber indicator on the right side of the gun. It is a  spring-loaded vertical bar of metal which stands out from the frame. When there is no cartridge in the chamber this bar can be pushed inside otherwise it is blocked and does not move. So by pushing that bar the operator could easily check if there is a cartridge in the chamber.

The magazine holds 5 rounds and the release button is at the front of the frame. This is not a very comfortable position but a logical consequence of the desire to keep the gun slim.   The magazine has four holes drilled on each side which allow a visual check of the number of cartridges. The baseplate is held in position by flanges which are bent over from the sides, similar to the Ortgies magazine.

Fritz Mann’s patents for the Model 1920/21:

• German Patent No. 334098 (4 March 1920) for a chamber groove to reduce breech weight.
• German Patent No. 332281 (17 March 1920) for the rotary bearing of the barrel.
• German Patent No. 345118 (30 March 1920) for an indirect safety which affects the trigger bar.
• German Patent No. 361248 (15 June 1921) for a combined ejector and loaded chamber indicator.

The Mann pistols Model 1920 and Model 1921 have only minor differences in the form and checkering of the safety lever, the cover plate and the position of the grip screw. The loaded chamber indicator on the right side of the Model 1920 was eliminated in the Model 1921.

I have three Mann pistols - a model 1920 (serial number 2800) with aluminium grips and two model 1921 (serial number 18768 and 32838) with rubber grips. The serial numbers are stamped on the front of the frame below the magazine release button. Behind the serial number you can find an additional number which are the last two digits of the model year. The milled frames have plain flanks which form a triangular area at the back of the gun. The size of that area differs on all pistols, but I can not assess if this can be used as a criterion for model determination.

We can at least assess that there have been aluminum and hard rubber grips and perhaps wood. Nearly all Model 1920 Manns I have found have aluminum grips excepting a very early gun which has wooden grips. Those wooden grips might be later replacements. The Model 1921 guns have hard rubber grips. Aluminium and rubber grips show the word “MANN” in an oval.

Hermann Historica, an auctioneer in Munich, is a great source for vest pocket pistols in excellent condition. They have a great archive of previous auctions which is always worth investigating. My three Mann pistols have slightly different inscriptions and in the Hermann Historica archive I found a very early nickel plated gun with SN 188 and wooden grip plates which should represent the very first style of inscription. The more guns I observed the more different inscriptions I found. As the guns do not differ very much, I arbitrarily named them as first, second, third variant and so on. By presenting the serial numbers which I found for each variant we can see that there are sometimes only a few hundred guns with certain inscriptions. If someone has a .25 ACP Mann pistol which has another inscription, I will gladly add more variants.*

First variant  - Model 1920 (SN 188)
The first variant shows the following inscription on the left side in sans-serif characters:

Jn & Auslands-Patente

Fire and safe position are marked with the german words FEUER and SICHER in sans-serif characters.

Second variant  - Model 1920 (SN 1268)
This variant shows the following inscription on the left side in italic serif capital letters:

JN & AUSLANDS-PATENTE

Fire and safe position are marked identical to the previous variant.

Third variant  - Model 1920 (SN 2421, 2800, 3004)
This variant shows the following inscription on the left side in sans-serif capital letters:

MANN’S PATENT

Fire and safe position are marked identical to the first variant.

Fourth variant – Model 1921 (SN 18768, 18903, 24522)
The left side of the gun is marked with italic serif capital letters and shows the inscription

FRITZ MANN, SUHL – PATENTE

The safety is marked with capital letters S and F. In the back there is a stylized MA in a circle which is the trademark of the Fritz Mann company.

Fifth variant – Model 1921 (SN 21629, 25769, 32838, 33555, 35535)
The gun is marked with italic capital serif letters.

MANN’S – PATENTE

Safety marking and trademark are identical to the previous variant. 

Although I found a gun with serial number 35535, it is highly questionable if that is an indicator for the total number of guns produced. Several sources estimate that the total production might be less than 20000. Wahlen reports that the Mann pistol was produced from 1920 to 1923/24 and that already by 1924 the gun could not be found in gun catalogs.

In a nutshell, Fritz Mann produced a very interesting vest pocket pistol with unusual features. The idea of hampering the case extraction with a chamber groove was a milestone but it did not achieve acceptance – perhaps due to safety issues. Later his idea–slightly different and in combination with other features–proved to be reliable enough and was found especially in automatic guns (e.g. Heckler&Koch G3). The interesting fact is that this idea was “reinvented” several times, and Fritz Mann did not win any laurels for his patent.

Having read Rieger’s article about the exploded gun I was first dubious about taking my Mann pistols to the range. But I wanted to provide information about both the reliability and precision of the Mann. So I test fired a few magazines out of one of my pistols. What should I say? The gun worked without mailfunctioning and although the barrel seems to be not the best I was able to hit a rectangle of 1 foot by 1 foot at seven meters. Balance in the hand is okay, but the sights are terrible and no real help for aiming.

In conclusion, the Mann pistol is not perfect but adequate for self defense. Being not much bigger than a credit card they fit easily into your pocket. From the historical perspective they are nice tiny pieces of steel which are continuing proof of the vagaries of the countless weapon manufacturers of the 1920s.

Stripping the Mann Pistol

1. Check that the magazine and chamber are both empty.
2. Pull the trigger to uncock the striker.
3. Pull the breech half way back, turn barrel counterclockwise 90° and remove it
4. Screw out spring bolt and remove breech block
5. Remove firing pin and spring
6. Remove grips and trigger bar with the safety lever in middle position
7. Remove trigger assembly and magazine  catch
8. Remove indicator pin and ejector
9. Pull out breech assembly through the front opening of the frame

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*  If you can provide photographs, serial number and model  information, or any other information about the Mann pistol, please write to [email protected].

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