9mm Mors wz.39
By Leszek Erenfeicht

In the early 20th Century, Europeans were still teaching their youth classical, long dead languages - Latin and old Greek. As a result, many technical inventions of that era bore Latin and Greek names, television or bathyscaph being just two examples. The two most renowned Polish pre-World War II gun designers, Piotr Wilniewczyc and Jan Skrzypinski, also christened their designs with Latin names. Most firearms aficionados have at least heard of, if not actually handled, the wz.35 Vis (Latin for “Power”) pistol from Radom. Their other 9mm design with a Latin name remained hitherto almost unknown. It was the submachine gun they called the Mors - Latin for “Death”. In reality though, it turned out to be not that deadly at all.

Birth of the Death

Many inventors of the time were proposing submachine guns of their own design to the Infantry Board of the modernizing Polish Army in the early 1930s. Of these, a blow-back operated, select fire weapon with a quick-change barrel and vertically positioned magazine, by Skrzypinski and Wilniewczyc, was chosen for further development.

When executed in metal and put to various tests, their project proved to suffer from an excessive cyclic rate of fire (over 1,200 rpm). Due to that, its 24 rd magazine capacity (governed by the size of the 9mm military ammunition pack, tailored to the Vis pistol ammunition allowance of three 8-round magazines) lasted only for 1.25 seconds of fire. With this excessive cyclic rate went the excessive dispersion of hits. Nevertheless, the military testing board saw some merits in the weapon and recommended alternations to be made.

These were implemented by a team of young designers from Warsaw’s Panstwowa Fabryka Karabinow (PFK, the State Rifle Factory), headed by Wilniewczyc and included Ryszard Modzelewski, Jerzy Podsendkowski (who later created the revolutionary compact MCEM 2 submachine gun that greatly influenced the design of the Uzi), Waclaw Dworzynski and Jan Potynski. They were redesigning the weapon according to a new specification, based on the results of the comparative tests of several European and one US submachine gun, staged by Instytut Techniczny Uzbrojenia (ITU, Ordnance Technological Institution) at the Infantry School in Rembertow, a suburb of Poland’s capital Warsaw, during the spring of 1937. The Swiss SIG-Neuhausen copy of Schmeisser’s MP 18.I, Finnish Suomi, German Erma EMP and US Thompson M1928 submachine guns were tested to establish the characteristics to be embodied in a new weapon. The Erma was found the most suitable for infantry use, with only the side-protruding magazine to be considered a primary fault.

A second improved prototype, and the first to be called Mors, was made at the Warsaw’s PFK and put to tests at the Instytut Badan Balistycznych (IBBal, Ballistic Research Institute) in Zielonka near Warsaw. Upon completion of the very thorough test program, a comparative test with the EMP was staged in April of 1938. The test board found accuracy in both semiautomatic and full automatic fire “unacceptable”, blaming it on the shorter barrel versus the EMP’s (210mm compared to 320mm). Additionally, the initial velocity was 12 meters per second lower than that of EMP. Test shooters complained about the front sight blade being too wide and rectangular in section, contrary to the inverted V to which they were accustomed. The sight radius, being shorter than EMP’s, and a loosely fitting quick-change barrel did not aid in accuracy, either. The cyclic rate of fire was lower than with the former prototype, but still deemed excessive at 750 rpm, compared to EMP’s 520 rpm. An “excessively stiff” mainspring and “too short” (109mm compared to 120mm in EMP) bolt travel were blamed for the high rate of fire. “Excessive length” of the stock and “wrong position of the foregrip” were found to be the cause of the weapon’s uncontrollability in full automatic fire. Placement of the foregrip, too far forward for the average shooter, was dictated by the magazine-well being incorporated into it. It is an idea worthy of note, as it returned to the Podsendkowski’s revolutionary MCEM 2 of 1944, where the magazine-well was also incorporated into the grip.

The first Mors was therefore not a particularly impressive weapon; but not a complete failure, either. The test results drew attention of the Inspektorat Broni Pancernej (IBPanc, Armored Troops Inspectorate), long searching for a prospective firearm to arm tank crews. Their two mainstay tanks at that time were the two-man TK/TKS tankettes armed with a single 7.9mm Hotchkiss wz.1925 machine gun and a Polish-improved version of the British Vickers Carden-Loyd one-man tank, in which a trooper hardly had space to sit properly, let alone handling any weapon. As long as he was actually able to sit in his tank, that was not a problem, but after being forced to bail out, the only means of fighting his way back to his lines was a mere pistol. Even with a pistol as good as the Vis was, this was much too less a weapon to be adequate. The IBPanc wanted a submachine gun, but there were not any to choose from at that time. Instead, in 1932, they proposed to stock the Vis pistols, and then in 1936 commissioned the Radom factory to make them fire fully automatic. The stocked pistol-carbine idea was bought by the Infantry Board, and all Polish-made Vis pistols were cut to accept the stock lug. On the other hand, though, the machine-pistol idea was tried, but the Infantry Board was against it. Then the IBPanc heard about the PFK-designed submachine gun and shelved the stocked machine-pistol project, backing instead the “true” submachine gun program. The first Mors appeared to be just what the doctor prescribed - an 828mm long burp gun, quite compact for the era, needing only what seemed to be slight de-bugging.

The Mors test minutes were forwarded to the PFK and resulted in the delivery of two further improved variations (called “Model No. 1” and “Model No. 2”) of the third, completely redesigned prototype, called the Mors 2. Nos. 1 & 2 differed in their trigger mechanism; sight arrangement and magazine catch designs. Based on the comparative tests of the two, the No. 1 model with a fire-selector was rejected, while the No. 2 with dual triggers was to be further evaluated. Semiautomatic accuracy improved due to a longer (270mm), more tightly fitted barrel and redesigned sights. The initial velocity was now barely equal to the EMP. A weaker mainspring, coupled with elongated bolt travel, resulted in cyclic rate reduced to about 600 rpm. The stock was redesigned, the fore-grip separated from the magazine-well and moved back, towards the center of balance, then drilled through and fitted with a telescoping monopod. Nevertheless, the dispersion was still 40% higher than the EMP. It was much better than the former prototype, shooting 200 - 300% wider groups, but the dispersion in full automatic fire at a distance of 200 meters was still 300% larger than that of the EMP. The vertical dispersion in burst fire was especially large, and ironically, grew even larger, when fired from the very monopod meant to stabilize it. The Board blamed it on the still excessive rate of fire and lower, poorly balanced, weight of the weapon. The Mors 2 was indeed 690 grams lighter than the first Mors (3.95 versus 4.64 kg) and 520 grams lighter than the EMP. The test minutes recommended reduction of the cyclic rate to 500 rpm and increase the weight of the weapon back to about 4.5 kg, possibly by using a heavier barrel to aid in controlling muzzle-climb and help dissipate the heat.

The all new, fourth prototype, called the Mors 3, was to embody all of the above recommendations. Three prototype submachine guns with three magazines each were ordered from the PFK with delivery scheduled for January 10, 1939. These were put to various tests and the rate of fire was recorded as decreased to about 450 rpm due to the use of the pneumatic rate-reducer retarding the bolt travel. The new gun was accepted by the Komitet Zakupow Uzbrojenia (KZU, the Ordnance Procurement Board) that placed an additional order with the PFK for a test lot of 36 units of the “9 mm pistolet maszynowy wz. 39 Mors” (or “9mm M1939 Mors submachine gun”) for troop trials. The delivery of guns, each priced at Zloty 2,500 (then roughly $500), was scheduled for April 15, 1939, but actual delivery was postponed to June 3, 1939. The troop trials were conducted in the 39th Infantry Division, Military Police units and the 3rd Rifles Battalion in Rembertow.

The introduction of the Mors 3 was a major blow to the tankers. What began two years earlier as a 828mm long submachine gun, now concluded in a 970mm weapon, only about an inch and a half shorter than the service wz.29 Mauser rifle, long ago considered unsuitably long for tank crews use. They had to beat a hasty retreat to the stocked pistol idea. Vis wooden holster-stocks, that all the Vis pistols were cut for but never before were issued, finally were designed in early 1939 and a small quantity actually issued to the troops, as witnessed by ultra-rare surviving examples reported in Hungary, Finland and Canada. In the early 1990s, Thomas B. Nelson of the Collectors’ Armoury, Ltd. commissioned a batch of these to be reproduced in Poland, and reportedly got into trouble with the BATF who were not convinced that these were indeed replicas of the actually existing accessory.

As the PFK was already tooled up for serial production of the weapon, it is highly probable that it was continued during the siege of Warsaw, and several more Mors were made, presumably for the forces defending the capital. However, there is no data to support or deny this hypothesis.

The hunt for Mors

For a long time after the war the Mors submachine gun remained a half-legendary, esoteric weapon that everybody in Poland had heard of, mostly only in superlatives, but nobody knew about for sure. Much confusion was caused by Mr. Wilniewczyc’s own publication in Vol.1 (1959) of the “Muzealnictwo Wojskowe” periodical edited by the Muzeum Wojska Polskiego (MWP, Polish Army Museum) in Warsaw. In this publication, the sketch of the original Mors with a short barrel and fore-grip encompassing the magazine-well, was published as an illustration of the production model. Time appeared to treat the designer’s memory very badly, causing him to write much stirring nonsense about his own gun - the table below compares the data published there with the measurements taken from the actual gun.

After Mr. Wilniewczyc died of cancer in 1960, the nation-wide hunt for the Mors began. It was not until 1983 when the first two were found in Moscow’s Central Red Army Museum. No paperwork was preserved with them. The only records available showed that these came to the Museum from the Red Army’s small arms research institution during the 1950s along with about 100 other weapons. It is unknown whether these were captured by Soviet troops from the Polish or German troops. The two guns bore consecutive serial numbers - 38 and 39 - that suggests that these were taken from a warehouse rather than from field troops. The numbers also tends to suggest that these were the last examples of the 36-gun batch ordered on top of the three Mors 3 prototypes.

Serial number 38 Mors is now on display in Warsaw’s Polish Army Museum and is preserved in fair condition but is missing the magazine, rear tangent sight leaf and trigger mechanism springs. It also has a mock barrel, closely patterned after the barrel of the S/No. 39 still in Moscow. A coned muzzle with a perpendicular undercut suggests that some kind of muzzle-device was provided or intended, but there is no information of it in preserved records.

The Pros and (Mostly) Cons of the Mors

The Mors wz.39 is a blowback operated submachine gun, firing from the open breech, fitted with a dual-trigger firing mechanism, quick change barrel, hold-open device coupled with a lever automatically releasing the empty magazine from the catch, pneumatic rate of fire reducer, and telescoping monopod.

The monopod is placed at the unloaded gun’s center of gravity and will stand on it without additional support. During firing, it was reported to actually help induce muzzle jump - just like in the Erma EMP from which it was copied. The monopod itself consists of three sections, one of which is permanently attached to the gun and serves as an axis for the foregrip. The other two are telescoping one into another, and the one with the smallest diameter has a rounded foot at the bottom. This foot also aids in retracting the monopod from the foregrip. It is an arduous task however, as the sections of the monopod are fitted very tight into themselves. Five times out of six you will tear the whole thing out of its socket instead of extending it. With some training you will learn to pull only in short strokes and then let go of it immediately after you feel it moved! Otherwise, you will finish up with movable parts of the monopod in one hand, and the gun in the other. It is also as tricky while shoving the thing back together. You have to find the little tongues with projections on their ends, resting under the rim of the wider tubes, depress them to hide these projections and then push the inner part in until the next stop. Then locate another pair of tongues and repeat the process. After you try to do it once, even without the opportunity to fire the Mors with the monopod, you will have enough of that for a lifetime.

Untypical for a weapon so full of gadgets and gimmicks, there are no safety devices other than the L-shaped cutout in the right rear part of the receiver. You have to retract the bolt past the sear and rotate the cocking handle into the slot, thus blocking it to the rear.

The trigger mechanism uses separate triggers for semiautomatic and full automatic fire. According to Mr. Wilniewczyc’s account, this idea was borrowed from the Chatellerault light machine gun, though it much more resembles the Italian Beretta submachine guns. In the accompanying drawings, the trigger spring [11] shape is hypothetical, as it is broken and only a part of it survived. There should also be some kind of a sear spring, but this is missing as well. Pulling on the full automatic (forward) trigger lowers also the semiautomatic trigger, but the full automatic trigger remains in position when the semiautomatic trigger is pulled. The disconnector [16] functions during the rearward travel of the bolt. The hold-open device incorporates as many as 10 (!) parts and is overly complicated even by the then popular construction standards.

The hold-open device operates as follows: The follower of the empty magazine raises the right arm of the lever [19], which in turn pushes the left arm of the hold-open [18] upwards. The bolt, traveling forward, strikes the hold-open, pushing it about 3mm forward, due to oval hold-open shaft openings in the walls of the trigger group housing. This movement pushes forward the auxiliary magazine catch [35], rotating on shaft [41]. The shaft [41] in turn acts on the upper arm of the magazine catch [20], thus disengaging it from the magazine [43]. By the way, this is about the only way to disengage the catch - it is flush with the stock and needs a narrow object being inserted into the opening to let the magazine go. The empty magazine cannot fall off because it is held in the magazine funnel by both the auxiliary catch [35], actuated by the flat spring [33], and the flat magazine retaining spring inside the magazine funnel. It can then be withdrawn without any further manipulations. Clearing the magazine will allow the auxiliary catch [35] to drop to a position in which the re-inserted clip will push it upwards thus raising the right arm of the hold-open. This will in turn disengage the left arm, allowing the bolt to go forward a few millimeters, until the sear engages, and the gun is ready to fire again. The magazine catch spring [21] will return all the parts to the battery.

The pneumatic rate of fire reducer operating principle is also shown in the diagram. In extreme forward and rear positions, the vents [b] and [c] will allow the air to bleed out, but during the movement of the parts these are sealed. During the forward travel a void occurs, and during the rearward stroke the air is compressed, in both cases slowing the action. Due to the non-shooting condition of the preserved gun, one cannot establish how really effective this device is. Nonetheless, even while cycling it by hand, one can hear the air hissing as it is sucked in and blown out. For the actual shooting results, we have to relay on the January 1939 test minutes, claiming the rate of fire in the vicinity of 400-450 rpm.

The quick barrel changing feature is one of the most doggedly discussed points of the gun. Ignoring the actual tactical virtues of the quick-change barrel design in a submachine gun (or the lack thereof), the solution used in Mors is very far from ideal. In theory, all you have to do to remove the barrel is rotate the barrel change lever-cum-disassembly pin clockwise through 180 degrees and point the barrel casing down. The heavy bull-barrel should drop out under its own weight. This author has some doubts about the good reason of the designers. In reality it still needs a hefty jerk of the weapon to disengage and fall. You better watch your feet doing this, as the barrel is heavy with sharp edges. I managed to punch a 2-3mm deep mark on the heavy oak floor boards of the museum’s warehouse, earning dirty looks from the otherwise very friendly museum staff! And, this was with a cold barrel! What about a red-hot, heat-swollen one? Re-inserting is tricky, too. There is a narrow re-aligning post buried deep inside the barrel bushing, which you have to align with an equally narrow slit in the barrel. Again, in theory, that may sound OK, but in reality, it is positioned so deep that one can only pray to re-align the barrel with a first drop. If one misses, the barrel sticks inside the casing, and suddenly all you have above the rim of the barrel jacket to hang on to and try to rotate it into position, is a roughly half inch conical-shaped muzzle. There are special openings in the bottom of the barrel jacket to assist in aligning the barrel - but they are of little use after dark. The whole barrel change process is a slow one and requires a lot of concentration and attention from the operator. A highly undesirable feature under actual combat conditions.

Thankfully, hardly any of these were actually issued prior to the September 1, 1939 German invasion!

This article first appeared in Small Arms Review V8N3 (December 2004)
and was posted online on June 28, 2013


Comments have not been generated for this article.