M31 Suomi Owners Manual

Finnish Suomi M31 Receiver Kit
Suomi M31 Receiver New

The M31 sub-machine gun is a neat weapon. Designed by Aimo Johannes Lahti in the late 1920s, the Suomi was instrumental in defending Finland against the Soviet invasion during the Winter War of 1939-40 and Continuation War from 1941-44. Years ago I picked up a couple cheap kits, one for a Beretta M38A and one for a Finnish Suomi M31, both SMG kits. This packet includes the steps necessary to build your own M31 semi auto receiver. The BATF letter included lays out the rules for manufacturing and proper marking. Please look at PN M31S-GNPT-XX09-BKXX-RCKT for a complete diagram.This Package is for the receiver only, not the complete rifle.

MACHINEPISTOLS, PART 1:

Bergmann and Suomi

7,65 mm Bergmann M/20:

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Merely said, the m31 suomi owners manual is universally compatible past any devices to read. Feedbooks is a massive collection of downloadable ebooks: fiction and non-fiction, public domain and copyrighted, free and paid. While over 1 million titles are available, only about half of them are free.
First is a suomi - m31 parts kit What you get, complete ready to weld reciever kit. Front trunnion is intact and machined to fit the repair section Semi auto converted bolt ( hammer style ) Horizontal cut lower with intact front filler and rear trunnion Rear end cap, origonal trigger group, sights and small parts And one stick mag.

PICTURE: 7,65 mm Bergmann M/20 submachine gun. (Photo taken in Sotamuseo). CLICK THUMBNAIL TO SEE LARGER PIC (40 KB).

Calibre:	7,65 mm x 21 Parabellum (.30 Luger)
Length:	815 mm
Barrel length:	200 mm
Weight:	4,2 kg
Fire-rate:	600/minute
Magazine:	box: 50
Magazine weight:	0,30 kg
Official abbreviations:	'7,65 kp/Bergmann'
Country of origin:	Switzerland
Prototype:	1916 (first version)
Production:	In Switzerland 1920 - 1927 (made in several countries).

Finnish use: Suojeluskunta (Finnish Civil Guard) acquired these submachine guns and used them in between 1922 - 1939. For Winter War (1939 - 1940) the great majority of Suojeluskunta weaponry was transferred to Finnish Army, among them these submachine guns were issued to Finnish Army front-line troops during Winter War (1939 - 1940). During Continuation War (1941 - 1944) coastal troops and home-front troops used them.

During World War 1 Hugo Schmeisser developed submachine gun MP/18-I, which German weapons factory of Theodor Bergmann started manufacturing in year 1918. The German Army soon accepted the weapon and Bergmann factory manufactured some 35,000 (or 25,000 depending source) by the end of World War 1. This weapon was the first practical machinepistol / submachine gun. Even if German Army managed to issue less than 10,000 before end of World War 1 the gun gained such a reputation that Versailles peace treaty ending the war specifically listed submachine guns among weapons banned from German Armed Forces. The original MP/18-I submachine gun had a weak point in form of its magazine, which was far from ideal: It used so-called snail-drum magazines, which Tatarek and Von Benkö had originally developed for artillery version of Parabellum pistol).

PICTURE: Photograph showing Corporal of Finnish Civil Guard with Bergmann submachine gun. Photographed by Bernard Åström in year 1920. (Acquired Finna.fi - original photo owned by Svenska litteratursällskapet i Finland). CC BY 4.0 Creative Commons license. CLICK THUMBNAIL TO SEE LARGER PIC (113 KB).

Soon after World War 1 Schmeisser developed improved submachinegun design directly based to MP/18-I for Bergmann factory. The main improvement of this new weapon was that it used normal box magazines. Year 1920 Bergmann sold manufacturing license of this improved MP/18-I now known as Bergmann to Swiss weapons factory S.I.G. (Schweitzerische Industrie-Gesellschaft). After making the deal S.I.G. started manufacturing Bergmann submachine guns in several calibers. S.I.G. manufactured Bergmann submachine gun was exported to several countries including Japan, China and Finland between 1920 - 1927. The Japanese and Chinese Bergmann submachine guns were made in 7,63 x 25 Mauser. Also Estonian Tallinn model 1923 submachine gun manufactured in only small numbers was directly based to MP/18-I and therefore close relative of Bergmann submachine gun. Production of Bergmann submachine guns in S.I.G. factory ended year 1927. S.I.G. factory introduced improved version of this weapon in year 1930, but with very little commercial success. With Bergmann submachinegun no longer selling, S.I.G. moved its interest to MKMO submachine gun (which was later developed to MKMS submachine gun). As a paraller development in Germany the development of improved MP/18-I led to introduction of MP/28-II submachine gun.

PICTURE: Top view to Bergmann and MP/28-II submachine guns. The two guns look almost totally alike, hence separating them from one another is often not easy. In this photo the gun on the top is Bergmann, while MP/28-II is below it. In this photo the magazines are accidentally next to the gun that they not used with - the longer 50 round magazine being correct for Bergmann. Photographed by Nousiainen in Weapons Depot 1. (SA-kuva.fi photo archive, photo number 113064). CLICK THUMBNAIL TO SEE LARGER PIC (65 KB).

Finnish Army was not interested about submachine guns in early 1920's, like most Armies of that time it doubted if this type of weapon would be useful to military . However, Suojeluskunta (Finnish Civil Guard) was more open minded when it came to acquring new weapon types and it bought first 1,000 Bergmann submachine gun already year 1922. Admitted in 1920's Civil Guard had also internal security role, due to which some of its duties were partly not that far distanced from that of a police force. By July of 1932 Suojeluskunta had acquired total 1,415 submachine guns. Around that point Suomi M/31 replaced Bergmann in acquisitions of submachine guns. Once Finnish Army finally had become convinced about the excellent qualities of Suomi M/31 also Suojeluskunta decided to follow its example and from that on acquire Suomi M/31 submachine guns instead of Bergmanns. It is noteworthy that particularly in 1920's Civil Guards were frequently loaning their Bergmann submachine guns to Frontier Guard, which had practically no automatic weapons of its own at that point.

PICTURE: Finnish ski patrol photographed in Märkäkäjärvi in February of 1940 during Winter War. The point man of patrol has Bergmann submachine gun hanging on his chest. (SA-kuva.fi photo archive, photo number fu_2653). CLICK THUMBNAIL TO SEE LARGER PIC (114 KB).

When Finnish - Soviet Winter War begun in November of 1939 Suojeluskunta's Bergmanns were transferred to Finnish Army, which suffered from serious shortage of automatic weapons. Finnish Army issued them to frontline troops for Winter War. Additional 108 Bergmann submachine guns were also bought from Switzerland during Winter War. 100 of them were the same 7.65 mm x 21 Parabellum calibre weapons as the earlier acquired Suojeluskunta Bergmanns, but eight guns seem to have been 9 mm x 19 Parabellum calibre version. Helsinki-based company Ilmakunnas

Finnish Suomi M31 Receiver Kit

acted as go-between in this deal in which the weapons arrived by very long route via Le Havre (France) and Stockholm (Sweden). In addition to those Switzerland offered also 290 Bergmann in 7.63 mm x 25 Mauser caliber, but the Finns decided not to buy them (presumably because yet another new calibre for submachine guns would have complicated ammunition supply). During World War 2 Finnish military issued Bergmann submachine guns with four magazines, spare barrel and magazine loading tool. June of 1940 Finnish inventory contained 1,415 Bergmann submachine guns, from which 1,1396 guns were in 7.65 mm and 19 guns in 9-mm caliber. During Continuation War (1941 - 1944) Bergmann submachine guns were first issued to coastal troops, but captured Soviet submachine gun soon replaced them in that use, so they were transferred to home front troops. In this way they in a manner returned home as basically home front troops contained mostly Suojeluskunta members, who were not fit for frontline duty and during the war General Headquarters of Civil Guard served as Headquarters for Home Front Troops. While Bergmann submachine guns officially remained to be property of Civil Guard, this would be as close it came for Suojeluskunta to ever get them back. One of the Soviet demands in Finnish - Soviet Peace Treaty of 1944 was disbanding of Suojeluskunta, which was disbanded in November of 1944. Once this happened the remaining Bergmann submachine guns remained with Finnish Army. After World War 2 Finnish military scrapped quite a lot of small arms that were in poor shape, but apparently Bergmann submachine guns, which had not seen much combat use since Winter War had remained in relatively good condition, since year 1951 inventory of Finnish Armed Forces still contained 1,307 of these guns. Finnish Defence Forces kept Bergmann M/20 mothballed for possible further use until they were sold to Interarmco in year 1960 and exported.

PICTURE: Finnish coastal infantry packed in boats on its way to inspect island that was in Soviet controlled area. Soldier has rested down his Bergmann submachine gun on bow of the boat. Photographed by 2^nd Lieutenant Pentti Nikulainen in October of 1941 in area around Hanko / Hango / Gangut Peninsula. (SA-kuva.fi photo archive, photo number 63734). CLICK THUMBNAIL TO SEE LARGER PIC (115 KB).

Lindelöf submachine gun, Finnish copy of Bergmann:

Finnish Leonard Lindelöf's machine factory got itself license for production of Bergmann submachine gun in 1922. As the name suggests Leonard Lindelöf owned the factory. submachine guns that this factory was to manufacture under license were exact copies of Swiss Bergmann M/20. Lindelöf had grand plans of large-scale mass-production of submachine guns and invested accordingly. Early on the prospects for this factory looked positive as the first order arrived swiftly - Suojeluskunta (Finnish Civil Guard) ordered 200 submachine guns identical to 7.65-mm Bergmann M/20 in December of 1922. But then Lindelöf's factory run into problems - it had promised delivery of these 200 weapons in just 8 months and this proved much too little. Production-wise Bergmann-submachine gun was typical 1st generation submachine gun - complicated weapon with its parts machined from steel. So manufacturing them was slow and demanded large number of tools and machinery. Time needed setting up production had been seriously underestimated and even suspicion of sabotage surfaced. These delivery delays were breach of contract and because of them Suojeluskunta cancelled its order. Heavy hit came when Swiss played Lindelöf out from competition by offering Bergmann SMG with bargain prices to Suojeluskunta in 1923, these bargain priced Bergmann submachine guns filled the needs of Suojeluskunta and lead into situation in which Suojeluskunta no longer had needs to buy more submachine guns for some time. Because of this Lindelöf's lost his only important customer and when first submachine guns made by his factory finally were finished in 1925 the factory had sell them in small quantities to any authorities willing to buy (local level Suojeluskunta organisations, Police, Customs, Coastal Guard, Estonian Police etc...). The factory had about 160 mostly unfinished submachine guns warehoused, but no clients for them.

Year 1930 Lindelöf contacted again Suojeluskunta trying to sell the remaining submachine guns. However Suojeluskunta was loosing interest as the new Suomi submachine gun made Bergmann-design look outdated. Soon after this Lindelöf's factory faced financial difficulties. Year 1932 he contacted again Suojeluskunta, who decided to help the factory by ordering 10 submachine guns, which the factory was to manufacture from its unfinished parts. The factory gave Suojeluskunta 12 already finished submachine guns as a pledge. But once again keeping to the contract proved impossible for the factory - as earlier the delivery was delayed again and again. Suojeluskunta had no other option than cancelling the contract and take possession of the 12 submachine guns earlier given as a pledge. The final nail to coffin for Lindelöf's plans was when Suojeluskunta that same year made decision from that on to buy only Suomi M/31 submachine guns instead of Bergmanns. Lindelöf had acquired the tools and machinery made for production of Bergmann submachine guns, but now had to sell the unfinished parts and tools as junk. Lindelöf version of Bergmann submachine gun when compared to the Swiss one was not such a high quality and its magazines were not interchangeable, but otherwise the weapons were identical. The small amount of Lindelöf made Bergmann submachine guns were used the same way as the Swiss made ones and got experienced exactly the same fate in Finland during World War 2 and after it. The estimated total production of Lindelöf submachine guns was only about 60 or 70. While Lindelöf's factory never again manufactured complete firearms it manufactured parts for some weapons still during World War 2.

Suomi submachine gun:

Prototypes:

According Aimo Lahti himself interest for designing submachine gun of his own born because Bergmann submachine gun was so expensive and not very good. Lahti started thinking that he would be able to make a better submachine gun - and he proved to be right. 1^st of June 1921 Aimo Lahti was hired as gun-master to Keski-Suomi Regiment and started developing his idea of submachine gun soon afterwards. First prototype he ordered was a miniature of sort in 7.65mm x 17 (Browning aka .32 ACP) calibre, only about 30 cm long and made by blacksmith in Viiala for him. The first prototype was no work of art but it proved that the basic construction that Lahti had designed was a working one.

Year 1922 he ordered the first real sized prototype (M/22), which was build by Machine workshop Leskinen & Kari in Tampere. It was in 7.65mm x 21 (Parabellum) calibre and had the same rate of fire as in later M/26. Lahti got support from commanders of Keski-Suomi Regiment Colonel-Lieutenants W. Hägglund and E. Heinricks, but they did not manage to get any state financing for this development work. Spring of 1923 the prototype was sent to Defence Ministry, but it failed to raise interest. M/22 was not exactly well made or ready for production, but it had plenty of hidden potential.

Suomi M31 Receiver New

October of 1923 Aimo Lahti and Lieutenant Yrjö Koskinen, an officer serving in Keski-Suomi Regiment acquired patent for Suomi submachinegun. June of 1924 the established Konepistooliosakeyhtiö (= Submachine gun Ltd) with two more officers serving in the same regiment. The other shareholders of this new business enterprise were Captain V. Korpela and Lieutenant L. Boyer-Spoof (who later changed his sir-name to Poijärvi). The number of shares in the company was 150 total. From those shares Lahti got 45, Korpela 45, Koskinen 30 and Boyer-Spoof 30 shares. This new company had a lot of inspiration, but very little finances. In fact some of its owners proved to be even too inspired - Lieutenant Korpela had to leave the company after trying to sell the submachine gun abroad without permission of other shareholders. Since value per share was 500 Finnish marks, at least on paper the total capital of the company was 75,000 Finnish marks. Year 1930 the company sold its patent of Suomi submachine gun to Tikkakosken Rauta ja Puuteollisuusyhtiö (= Tikkakoski Iron and Wood Industry Ltd) for 65,000 Finnish marks and 5 % royalty from all Suomi submachineguns that Tikkakoski manufactured.

PICTURE: Suomi M/26 submachine gun with its rather eccentric looking 36-round magazine. Notice the fire selector switch on side of the weapon and barrel jacket quick release latch on top of the magazine. (Photo taken in Metsästysmuseo). CLICK THUMBNAIL TO SEE LARGER PIC (40 KB).

7,65 mm Suomi M/26:

Lahti was improving his submachine gun-design all the time making several improvements, which were all patented in Finland as soon as they had been invented and development was starting to look ready for mass-production. Konepistooliosakeyhtiö ordered one hundred submachine guns from Ab Tool Oy and at August of 1924 also Finnish Defence Ministry finally got interested. February of 1925 first batch of 13 submachine guns were inspected by Ordnance Department of Finnish Armed Forces. The weapons worked well, but their magazines only worked with individual weapon to which they had been intended and gun barrels were already slightly corroded. However, they passed the inspection regardless these minor issues. Army ordered additional ten submachine guns in October of 1925 and another 39 in March of 1926 and even bought earlier made prototypes. This proved highly useful since at that time Konepistooliosakeyhtiö and its shareholders were just about broke, so they needed every possible bit of money that they could get. From this production series of about 100 weapons most (over 60) ended up to Finnish Army, but also Suojeluskunta (Finnish Civil Guard) and Frontier Guard bought them in small numbers. Few weapons of this series were delivered abroad as samples (among them 5 to Estonia). Later submachine guns of this production series were named as M/26 to make them easily separated from M/31 Suomi. Suomi M/26 ended up costing only about 2,200 Finnish marks/submachine gun while Bergmann at that time cost usually more than double (4,500 Finnish marks). Arch-shaped 36-round magazine used with Suomi M/26 was unique in that sense, that it was not used in any other weapon. Full magazine weight about 800 grams. Like later M/31 also M/26 had quick release system, which allowed changing its barrel in matter of seconds. Normally they were issued with spare barrel and tool pouch.

PICTURE: Sentry of Supply Training Center in Mänttä with his Suomi M/26 submachine gun. The ETP roadsign nex to him is for food items supply point. Photographed by Vuorela in January of 1942. (SA-kuva.fi photo archive, photo number 69008). CLICK THUMBNAIL TO SEE LARGER PIC (167 KB).

Suomi M/26:

Calibre:	7,65 mm x 21 Parabellum (.30 Luger)
Length:	930 mm
Barrel length:	350 mm
Weight:	4,18 kg
Fire-rate:	600/minute or 750/minute depending sources
Magazine:	arch: 36
Abbreviations:	'7,65 kp/26'
Country of origin:	Finland
Prototype:	1924
Production:	About 100 made between 1925 - 1926.

Suomi M/26 never saw real combat use, during World War 2 they were issued troops doing guard duty in home front. During the war they were apparently issued with only two two magazines per weapon - quite likely due to limited number of magazines originally manufactured for them. Year 1959 the remaining 57 Suomi M/26 were sold to Interarmco and shipped abroad year 1960. This was a one of the darkest moments of Finnish weapons history as along the 'ordinary' M/26 also all its one of a kind prototypes were sold without understanding their historical value. Luckily they at least were not scrapped, when they ended up to foreign museums and arms collectors.

9 mm Suomi M/31:

PICTURE: Early version of Suomi M/31 submachine gun with 70-round drum magazine. (Photo taken in Sotamuseo). CLICK THUMBNAIL TO SEE LARGER PIC (76 KB).

PICTURE: Late version of Suomi M/31 submachine gun aka M/31 SJR with 50-round box magazine. Notice muzzle brake in end of barrel. (Photo taken in Sotamuseo). CLICK THUMBNAIL TO SEE LARGER PIC (76 KB).

Aimo Lahti was not happy with M/26 submachine gun, its feeding process was not as reliable as it should have been and the stock was not robust enough for first grade military weapon. Submachine gun M/26 also shared several design weaknesses of foreign submachine guns like MP-18/I and MP-28/II, which Lahti succeeded fixing while developing submachine gun M/31. He eliminated the excessive room in front of bolt (which had allowed cartridge every now and then to turn sideways, which jammed the weapon) and the feeding problems disappeared. The quick-release method used for attaching the barrel and barrel jacket to receiver allowed barrel to be quickly replaced if needed. Barrel of the weapon also sported new tilted end, which somewhat decreased tendency of muzzle to climb during shooting. The barrel jacket around the barrel was modified to be structurally more simple and robust. However, the most important change that came with submachine gun M/31 was changing of calibre to 9 mm x 19 (Parabellum), as this new ammunition allowed development of new magazines, which would not have worked as well with bottle-necked 7.65 x 21 (Parabellum) cartridge. Lahti designed all these improvements plus new 20 round box magazine and 40 round drum magazine around 1930 - 1931. This finally spared interest of Finnish Ministry of Defence, but there was no yet factory for manufacturing this new submachine gun.

PICTURE: Empty 40-round drum magazine opened. This magazine was designed by Aimo Lahti in year 1932. Fully loaded it weights exactly the same as 70-round drum, but was also much more difficult to load, as bullets had to be placed on their tips when loaded to magazine. When this magazine design proved also somewhat unreliable, it is not surprising that its production ended already in year 1939. Nowadays 40-round drums for Suomi submachine gun are very rare and valuable. CLICK THUMBNAIL TO SEE LARGER PIC (129 KB).

Engineer Oscar Östman, who was leading Tikkakoski Rauta ja Puuteollisuusyhtiö (= Tikkakoski Iron and Wood Industry Ltd) at that time knew Lahti personally and was also very interested about the new submachine gun M/31. Tikkakoski was already manufacturing parts for weapons such as rifle and machinegun barrels for Finnish military, so it had also some experience of weapons manufacturing and selling products to Finnish military. Shareholders of Konepistooliosakeyhtiö finally earned from their work when Tikkakoski bought the mass production rights of submachine gun M/31 as its sole manufacturer. This ended the story of Konepistooliosakeyhtiö, which now had served its purpose.

PICTURE: Fully loaded 70-round drum magazine opened. Lid of the magazine in left side of the photo. The actual maximum capacity of this magazine type is 72 rounds, even if Finnish military prefers to call it 70-round magazine. Experiences suggest that there was a reason for this - loading only 70 rounds instead of 72 seems to increase reliability of this magazine model. CLICK THUMBNAIL TO SEE LARGER PIC (57 KB).

While Suomi submachine gun was finally getting recognition it earned, the early magazines (20-round box and 40-round drum), which Lahti had developed in early 1930's proved less than ideal. 20-round box magazines existed in two versions, which actually had maximum capacity of 25 rounds, but if filled to full capacity they had reliability issues, while when loaded only with 20 rounds they worked rather well. The 20 round magazines were quite small and handy (they weight only some 0,2-kg empty and 0,44-kg when loaded with 20 rounds), but also had too small ammunition capacity and proved too difficult to fill fast, so their production was ended already before year 1939. Production of 20-round magazines was restarted during Winter War, but once Winter War ended the production was stopped again - this time definitely. 40-round drum magazine proved unreliable, but even more difficult problem was with filling it - cartridges had to be inserted in such manner that they stood on tips of the bullets. Smallest mistake would cause the cartridges felling in their side inside the 40-round drum magazine, creating mixed pile with only one solution - drop all cartridges off the magazine and start the whole process of inserting cartridges from the start. In addition 40-round drum was not terribly effective for its size and weight - it weight 1,0-kg empty and 1,48 kg full while 70-round drum weight 0,87-kg empty and 1,48-kg when fully loaded, plus the two magazines are about the same size. The magazines typically used with Suomi M/31 during World War 2 were 70-round drum and 50-round box. From these two, the 70-round drum magazine became the best known magazine for Suomi submachine gun, but not necessary the most commonly used. Yrjö Koskinen (one of shareholders in Konepistooliosakeyhtiö) designed the 70-round drum without Lahti even knowing about this new magazine type before it was finished. Koskinen's drum magazine proved to be the best magazine available for Suomi M/31 during World War 2 - it was reliable, handy (even if somewhat heavy) and offered excellent firepower. In addition unlike many other drum magazine designs this magazine did not allow cartridges loaded inside it to rattle. Downside was that much like Suomi M/31 itself, the magazine type required high quality materials and was both slow and expensive to manufacture. Koskinen's 70-round drum magazine entered production in year 1936 and remained in production until late 1944. The 50-round box magazine was Swedish design, which Tikkakoski started manufacturing under license in year 1941. 50-round box magazine was not as good as 70-round drum magazine, but it was easier and cheaper to produce. However, the wartime use proved this box magazine to be structurally too delicate (smallest dent in the wrong place could jam it) and impossible to reload anywhere near full capacity without separate loading tool. Because of these reasons production of the 50-round box magazine was stopped in autumn of 1943, but before that happened total 145,850 had been produced. Rest of the war only 70-round drum magazines remained in production and became the most common magazine used with Suomi M/31 submachine guns during World War 2. Some 149,900 70-round drums were manufactured for Finnish military in 1941 - 1945, but 81,000 of those were not delivered until 1944 - 1945. Before and during World War 2 Tikkakoski, who was sole manufacturer of Suomi M/31 in Finland, was also the sole manufacturer for its magazines.

PICTURE: Sergeant of Finnish Army with Suomi M/31. The 70-round drum seen in this became the de facto standard magazine type for Suomi M/31 submachine gun during World War 2. The helmet is Swedish steel helmet m/37. Photographed by K. Kivi in July of 1941 in Häsälä. (SA-kuva.fi archive, photo number 27883). CLICK THUMBNAIL TO SEE LARGER PIC (129 KB).

The number of magazines that Finnish military issued with Suomi M/31 during World War 2 varied, but year 1943 this weapon was supposed to be issued with either five 70-round drum magazines or seven 50-round box magazines. The equipment used that Finnish soldiers often used to carry drum magazines of Suomi M/31 during World War 2 was somewhat improvised combination of hooks, straps and/or rope that allowed hanging drum mags to their service belt. There were no purpose-built magazine pouches in Finnish use, so soldiers also used variety of suitable bags for this purpose. These included bread bags, gas mask bags and magazine bags originally made for carrying of ten Lahti-Saloranta light machinegun magazines. Carrying box made from plywood was developed for 50-round box magazines and manufactured for home front troops (Civil Guard) during Continuation War. Typically only home front troops used these magazine boxes since they would have suited poorly for frontline use, as they were clumsy and made noise (magazines rattled inside them) during movement. Some sources claim that drum-magazines used in Suomi M/31 would be related to ones used in Thompson submachine gun, but this is false information. The only connection was in conceptional level - both Lahti and Koskinen may were likely aware about drum magazine(s) used in Thompson, but its unclear if this even effected to their decision of developing drum-magazines for Suomi M/31 in any way. From technical point of view both L- and C-drums used in Thompson are structurally and mechanics-wise totally different from 40- and 70-round drum magazines used with Suomi M/31.

PICTURE: 50 round box magazine for Suomi M/31 submachine gun. This magazine model was/is generally known as 'coffin-magazine' because of its shape. Filling more than 50 rounds to this was magazine was strictly forbidden because that usually results magazine getting jammed. CLICK THUMBNAIL TO SEE LARGER PIC (121 KB).

Magazines Finnish military used with Suomi m/31 submachine guns:

Magazine:	Capacity:	Weight Empty / Full	Manufactured:	Details:
20-round box	25	0.20 kg / 0.44 kg	1931 - 1940	Since 1941 in secondary use
36-round box	36	0.40 kg / 0.85 kg	1954 - 1958	Swedish m/54, Finnish m/55
40-round drum	40	1.00 kg / 1.48 kg	1931 - 1936	Mostly in secondary use
50-round box	50	0.39 kg / 1.02 kg	1940 - 1943
70-round drum	72	0.87 kg / 1.48 kg	1936 - 1944	Most common during WW2

PICTURE: Oops... Even if loading of 70-round drum magazine was much easier than the 40-round drum magazine, it still took only one clumsy move to make already inserted cartridges to overturn. Fixing a pile-up like this is not something that one would like to do in freezing weather or in middle of firefight. CLICK THUMBNAIL TO SEE LARGER PIC (54 KB).

It is not exactly common for small arms to be named after the country in which they are being manufactured, so in that sense this submachine gun getting named Suomi (Finland) was rather exceptional. It seems to be somewhat unclear who came up with the name first, but calling Lahti's submachine gun as Suomi submachine gun (Suomi konepistooli) had spread to Finnish military documents already in year 1925. The first public display of new 9 mm Suomi submachine gun and publicity given by Hakkapeliitta Magazine (magazine of Suojeluskunta aka Finnish Civil Guard) in September of year 1930 made Suomi submachine gun practically a household name both among Finnish military and Suojeluskunta organisation. October of 1931 Finnish Army decided to place its first order of 100 new Suomi submachine guns in 9-mm calibre - this resulted the weapon getting officially named 9 mm submachine gun M/31. Tikkakoski made Suomi submachine gun M/31 available with several options that included front handle, bipod and two alternative designs for selector switch. From these options Finnish Armed Forces ordered the most simple variation and stick with it. Also Finnish Civil Guard (Suojeluskunta) followed suit and decided to acquire the same version of Suomi M/31 that armed forces had already chosen from that on. Other available options of this weapon manufactured by Tikkakoski were sold only with export deals, which were far and few before World War 2, making them very rare.

PICTURE: Cut open Suomi M/31 submachine gun showing structure of the weapon. (Photo taken in Sotamuseo). CLICK THUMBNAIL TO SEE LARGER PIC (57 KB).

Before World War 2 Suomi M/31 was not selling and there were only few orders. By year 1934 the now more shortly named Oy Tikkakoski Ab had delivered only 375 Suomi M/31 submachine guns to Finnish Army. When Winter War started the total number of these weapons in use of Finnish Armed Forces was not more than about 4,000 and rapidly increasing their production proved difficult. Only about 730 were manufactured during this war. Production continued and expanded after Winter War and during Continuation War settled to level of 1,400 - 1,500 weapons per month. It could be noted that equipment delivered with Suomi M/31 were also somewhat exceptional for submachine gun. Most deliveries included spare barrels. The idea was that each of these weapons was equipped with two gun barrels (primary and spare), which both had similar dispersion and point of impact. With barrel quick release this allowed changing barrel even in middle of firefight without needing to adjust sights or loosing any shooting accuracy. Replacing barrel of Suomi M/31 is remarkably easy and fast and obviously designed for soldier in the field to do for his weapon when necessary - both gun barrel and barrel jacket are locked to weapon with one single simple switch. Also disassembling and re-assembling Suomi M/31 is quite easy. In fact the only remotely difficult part of doing this is re-inserting of recoil spring, which demands certain technique to make sure that the spring does not get bent.

Suomi M/31 'basic version':

Calibre:	9 mm x 19 Parabellum/Luger
Length:	870 mm / 925 mm
Barrel length:	314 mm
Weight:	4,72 kg / 4,9 kg
Fire-rate:	900/minute
Magazine:	boxes: 20, 50, drums: 40, 70 (72)
Abbreviations:	'9,00 kp/31' and '900 KP 31'
Country of origin:	Finland
Prototype:	1931
Production:	Estimated 80,000 manufactured 1931 - 1953.

During the war Finnish soldiers gave grateful feedback, but the feedback also revealed that Suomi submachine gun was not perfect. Tendency for recoil to cause muzzle climb still existed and was seen as largest remaining problem. When sudden spur of cases showing serious barrel corrosion spotted in January 1940 it was time believed to be result of snow and debris getting inside gun barrel, which caused necessity of finding a solution for this problem. The solution was to add a muzzle brake in the design. Only later on it was proved that the corrosion had been caused by use of wet ammunition. Both 13^th Weapons Repair Company and Ordnance Department of Finnish Army designed muzzle brakes for Suomi M/31. After some testing Ordnance Department selected its own version for production. This new muzzle brake was included into all Suomi submachine guns ordered by Finnish Armed Forces after February of 1943. Suomi M/31 ordered by HQ of Home Front Troops (GHQ of Civil Guard) and those made for export were not equipped with muzzle brakes even after this, they remained to be exactly same as the earlier version of M/31. The muzzle brake was 95-mm long and 28-mm thick, so it added some 55-mm to total length of the weapon. Aimo Lahti was not happy about muzzle brake being added to his invention, in fact his opinion was that it only decreased muzzle-velocity and lead to poorer reliability. Letters SJR (from word suujarru = muzzle brake) were soon added to naming of muzzle braked Suomi submachine guns for purposes of spareparts supply. During Continuation War Aimo Lahti designed also cheaper, faster and easier to manufacture version of 9-mm Suomi submachine gun called M/42, but it never got beyond prototype stage.

PICTURE: Suomi M/31 SJR submachine gun. CLICK THUMBNAIL TO SEE LARGER PIC (58 KB).

Bunker version of M/31 Suomi ('Korsu-kp'):

Calibre:	9 mm x 19 Parabellum/Luger
Length:	740 mm
Barrel length:	314 mm
Weight:	4,35 kg
Fire-rate:	900/minute
Magazine:	boxes: 20, 50, drums: 40, 70 (72)
Abbreviations:	'900 kp/31 korsu' and '900 KORSU KP 31'
Country of origin:	Finland
Prototype:	1939
Production:	500 manufactured in 1941.

Summer of 1939 it became clear that submachine gun Finnish Army needed submachine gun, which could be used shooting from vision slits or steel observation cupolas of bunkers. Ordinary Suomi M/31 submachine gun had barrel jacket, which made shooting the weapon from narrow vision slits difficult and also sights and butt structure poorly suited for this use. Ordinary Suomi M/31 submachine gun was also too long to be operated efficiently inside the observation cupolas. So a bunker version with longer and narrower barrel jacket, pistol grip and sights located in left side of the weapon was hurriedly designed. Prototypes were made and tested and the weapon received official approval in September of 1939. But then started Winter War ruining production plans, as resources needed for production were needed elsewhere.

PICTURE: Bunker-version of Suomi-submachine gun. This particular weapon is 'mass-produced' version of this weapon - one of the only 500 ever made. Notice the additional sights in side of the barrel jacket. CLICK THUMBNAIL TO SEE LARGER PIC (50 KB).

So, when Winter War started only few prototypes of this submachine gun version existed. Yet Finnish troops managed to get in their hands some Suomi M/31 bunker-submachine guns of one sort already during Winter War. Some barrel jackets of bunker versions had already been manufactured and during Winter War Finnish troops installing them to their ordinary Suomi M/31 submachine guns. The resulting weapon was so long that it could not be really used in observation cupolas of bunkers, but at allowed aimed fire through narrow vision slits. During Continuation War situation of bunker submachine guns improved as in January 1941 as part of order of 9,500 Suomi M/31 submachine guns also 500 bunker-version submachine guns were ordered. The early models of bunker submachine guns made for tests had 385-mm barrel jacket, special frame and wooden grips that came in two parts. In mass-production bunker-submachine gun version barrel jacket was 435 mm long, frame and grip structure resembled the ones used in ordinary version and sights were sturdier. Bunker versions of Suomi M/31 remained warehoused to depots of those areas of Finland that had fortifications until 1970's. After this some were given to museums and most went through modification process that made them ordinary Suomi M/31 submachine guns.

PICTURE: Version of Suomi M/31 for tank use. The total production of this rare version was probably only about 40 guns, since it was only used one tank model of Finnish Army. A special barrel jacket was used to install the gun into tank's firing port, but here the submachine gun is seen with normal barrel jacket. Photographed by Nousiainen. (SA-kuva.fi archive, photo number 113126). CLICK THUMBNAIL TO SEE LARGER PIC (35 KB).

Tank version of M/31 Suomi:

This was a special version made for Vickers 6-ton tank (later known as T-26E after equipping the turret with captured 45-mm Soviet tank gun and DT machinegun after Winter War). Those tanks had a firing port specially designed for this submachine gun in their front hull. If crew needed, they could easily remove the weapon from its firing port - when needed allowing it to be equipped with normal barrel jacket and to be used like a normal submachine gun. The tank version had a special barrel jacket designed to fit into firing port (permanently attached to the firing port) and pistol grip. While this weapon with its pistol grip resembled the bunker-submachine gun version, it has normal Suomi M/31 rear sight. When used in the firing port the submachine gun was equipped with simple optical sight. Only few dozen tank-version of Suomi M/31 were made before Winter War and those were the only ones ever made. Soviet DT machineguns were captured in large numbers already during Winter War and proved to be more effective in armoured vehicle use than tank-submachine guns. So, the tank-version of Suomi M/31 never saw mass-production. The total production was probably only about 40 weapons, from which 31 remained in summer of 1940. While the number was small they were intended only for 32 Vickers 6-ton tanks, from which 24 were modified as T-26E. These rare weapons remained included to official Finnish Defence Forces weaponry until 1980's (long after the T-26E tanks, in which they had been used, were all gone). This may have happened simply because nobody remembered to officially inform them not being needed anymore.

PICTURE: Finnish soldier with Suomi M/31 SJR. Photographed by Military official J.M.Vuorela in August of 1944 in Ladoga Carelia. (SA-kuva.fi archive, photo number 156396). CLICK THUMBNAIL TO SEE LARGER PIC (107 KB).

Experiences of Finnish Army:

Suomi M/31 submachine gun proved to be excellent submachine gun: It had superb firepower, excellent accuracy, good muzzle-velocity and outstanding reliability. Only minus for its users was its weight. When introduced in early 1930's Finnish Army integrated Suomi M/31 submachine gun to existing organisation of infantry. At that time Finnish rifle platoons each had four squads - two light machinegun squads and two rifle squads. Submachine guns were issued to rifle squads with one weapon per squad. While some sources suggest that due to this Suomi M/31 would have early on been intended to serve as kind of a replacement for light machinegun, this seems be inaccurate. Military manuals from 1930's suggest that main idea was to boost short-range firepower of rifle squad, which in tactical concept of 'fire and movement' were mainly responsible of movement, while light machinegun squads provided fire support for this. Still, in this tactical concept submachine gun played important role and was more of a squad weapon, than individual one. That part of the tactical concept proved to be a poor idea, but when the correct role for submachine gun was understood Suomi m/31 proved huge success. It proved remarkably effective once used as individual weapons issued to most capable soldiers. It gave these individual capable soldiers excellent short-range firepower in relatively compact form - light machineguns were notably large and heavy compared to it. Suomi submachine gun was unusually accurate weapon as a submachine gun and had longer range than most other submachine guns of its time. This was thanks to quite good ergonomics, rather long barrel (when compared to other submachine guns of that time), small recoil, powerfully loaded ammunition and quite a good sights. Rear sight is fully adjustable and has rather optimistically settings up to 500 metres, while front sight is drift adjustable. In Finnish forests effective shooting range of Suomi M/31 typically proved long enough and thanks to 70-round drums and fast rate-of-fire Suomi M/31 was able to spray more lead into air faster than grand majority of other automatic weapons of that time. Hence it is no suprise that Suomi M/31 become favoured weapon among Finnish troops as it proved to be ideal weapon for the best soldiers to make their most. Summer of 1940 armament of rifle squads belonging to Finnish infantry regiments got re-planned, now every rifle squad got both light machinegun (as squad support weapon) and submachine gun for short-range firepower. The number of submachine guns needed for making this a reality was lagging behind and 1941 many Finnish infantry regiments were still unable to equip all their rifle squads with submachine gun. Autumn of 1942 Finnish Armed forces finally had all the submachine guns needed for this purpose, but Suomi M/31 had proved so effective that at that point committee led by General Heinricks went ahead and decided to recommend adding second submachine gun to all rifle squads as soon as possible. By end of 1943 enough Suomi M/31 submachine guns had been manufactured for this new table of organisation and equipment to be fulfilled, so then decision about providing third submachine gun for each rifle squad was made, but this didn't materialise in large scale before Continuation War ended resulted halting of the Finnish weapons production. Early June 1944 number of Suomi M/31 submachine guns in use of Finnish Armed Forces had peaked to bit over 52,600.

PICTURE: Suomi M/31 has selector switch, which goes though front part of trigger guard. This selector switch has three settings (from front to back): automatic fire, semiautomatic fire and safe. The photo on the left shows the switch with setting 'safe' while the one on the right shows it with setting 'full auto'. CLICK THUMBNAIL TO SEE LARGER PIC (50 KB).

Suomi M/31 submachine guns delivered to Finnish Army between 1939 - 1944:

year	production
1939	1172
1940	3600
1941	11475
1942	13067
1943	15933
1944	11600
Total	56847

Notice: Those made for HQ of Home Front Troops (pre-war Finnish Civil Guard HQ), ordered by Interior Ministry or exported abroad are not included to these numbers.

Losses in battle, broken weapons and weapons hidden to weapons caches dropped number of Suomi submachine guns to just little bit over 40,100 by 5^th of October 1944. Repairs and weapons returned from weapons caches started slowly raising the number. August of 1951 Finnish Armed Forces had about 50,100 Suomi M/31 submachine guns and about 300 bunker-version of Suomi submachine guns. Some 27,800 of these remaining Suomi M/31 were the muzzle-braked equipped (SJR) version. Year 1953 Finnish Defence Ministry bought unfinished materials from Tikkakoski factory, these included 3,517 Suomi M/31 (that had not been previously finished). Summer of 1957 some 53,600 remained in ownership of Finnish Armed Forces. In mid 1950's new Swedish designed 36-round box magazine (which the Swedes had originally introduced for Carl Gustav m/45 submachine gun) was first bought from Sweden and soon introduced to production under license in Finland. In 1950's and 1960's these new 36-round magazines replaced old 20-round, 40-round and 50-round magazines, which were mostly scrapped. The new Swedish designed 36-round magazine proved excellent - easy to fill with cartridges, handy and reliable. From 1960's to 1990's old 70-round drums and new 36-round box magazines were the magazine types used with Suomi submachine guns. Assault rifles replaced Suomi M/31 in most Finnish military units in 1960's and 1970's, but large number still remained warehoused for reserves of Finnish Defence Forces until late 1990's. In 1990's AKM-type assault rifles bought from Germany and China finally replaced by then very old-fashioned Suomi M/31 submachine gun. The last use for which Suomi M/31 submachine guns were stored for before being retired was as weaponry for reserve police - a supplimentary police force to be activated in case of major crisis. Even today Suomi submachine gun had legendary reputation among Finns. Year 2016 in a poll Finns voted Suomi submachine gun as the second most important Finnish invention of 20^th century.

PICTURE: Finnish made 36-round box magazine used in Suomi M/31 and submachine gun M/44. In Finland Lapua was the sole manufacturer of these magazines, which were also known as M/55. The Swedish version (known as M/54) manufactured by AB Linde Kvarnmaskiner for Finland lacks the carrying loop, which was added to Lapua-made version. CLICK THUMBNAIL TO SEE LARGER PIC (36 KB).

Export deals of Suomi submachine guns before World War 2:

Before World War 2 orders of Finnish military were so small that capacity for export production existed, so Tikkakoski offered Suomi submachine gun foreign customers. Starting from 1931 several introduction tours were done by Aimo Lahti and Tikkakoski representatives to other European countries (mainly to Germany and Baltic countries), but projects for sales to more far away countries existed also. However gaining good export deals failed. Only somewhat large deal following from these efforts was for Estonian Armed Forces, which bought 485 Suomi M/31 submachine guns, which were delivered in September of 1938. Tikkakoski developed two versions (both called M/33) of Suomi submachine gun for Persia. These two M/33 prototypes had upwards pointing box-magazine on top of the weapon and bipod below barrel. The main difference between two M/33 prototype versions was pistol grip, which one version had and another did not. But due to changes in Persian political situation in Persia the actual order for M/33 never materialized. Smaller deals were also done with customers like Polish State Police (20 Suomi submachine guns delivered in 1933), but the success had to wait until World War 2. According what is known small numbers of Suomi submachine guns found their way to Chaco War (Bolivia vs. Paraguay 1932 - 1935) and to Spanish Civil War (1936 - 1939). Year 1940 French military had about 300 Suomi M/31 submachine guns, grand majority of these belonged to weapons confiscated from remains of Spanish Republican Army units, which had headed to France in end of Spanish Civil War.

Exports of Suomi M/31 submachine guns during World War 2:

During Interim Peace and Continuation War Tikkakoski also exported Suomi submachine guns abroad. Many of largest deals were made to insure getting vital machinery or raw materials in exchange. Export permits given in that time included:

Export Permits during Interim Peace and Continuation War.
14th of August 1940	220	to Sweden
14th of August 1940	5000	to Bulgaria, almost certainly no actual deal
31st of October 1940	50	to Sweden
16th of January 1941	26	to Denmark
18th of December 1941	5	to Bulgaria
20th of January 1942	40	to Sweden
12th of March 1942	1742	to Germany
20th of April 1942	10	to Sweden
26th of June 1942	1100	to Germany
26th of June 1942	500	to Bulgaria, probably no actual deal
26th of June 1942	100	to Sweden
22nd of October 1942	500	to Croatia
26th of November 1942	100	to Switzerland
29th of April 1943	7	to Denmark
20th of May 1943	5000	to Switzerland, all not delivered?
1st of July 1943	750	to Croatia, almost certainly no actual deal made
5th of August 1943	200	to Germany*
Total	15350

* Ordered by Privatkanzlei des Führers, Hitlers private chancellery. The weapons of this deal probably went to Waffen-SS.

(Source of this chart: Sotilaskäsiaseet Suomessa 1918 - 1988, part 2, page 267.)

In addition Romania wanted to buy 5,000 Suomi M/31 submachine guns in year 1942, but the deal did not happen as orders of Finnish military were a priority and there was not enough production capacity for both. For the same reason many of the planned export deals listed above could not be filled. In addition July of 1942 Finland donated 120 new Suomi M/31 submachine guns to German AOK Norwegen located in Finnish Lapland. Large number of the submachine guns sold to Germany seems to have ended up to SS and Waffen-SS, as they were typically issued more mixed weaponry than Wehrmacht (German Army). Depending order either 50-round box magazines and/or 70-round drum magazines seems to have been exported with the guns.

While during World War 2 Suomi m/31 saw use in addition of Finland mostly with neutral (Sweden, Switzerland) and Axis countries, also the western allies expressed considerable interest towards it. France had ordered one weapon for testing in January of 1940. 10th of June 1940 it ordered 150 submachine guns and expressed interest for buying manufacturing license, if the delivered weapons would pass testing. Due to Germany and France being at war and French surrender less than two weeks later, this delivery was never made. Great Britain expressed interest for buying manufacturing licenses of Suomi M/31 and Lahti-Saloranta M/26 light machinegun in August of 1940. Finnish foreign ministry replied this request by noting that Finland can not sell manufacturing licenses of military weapons to belligerent countries. From February of 1940 to early 1941 there were also plans and negotiations about exporting and starting licensed production of Suomi m/31 in United States - while the gun was tested on Aberdeen test ground in July of 1940, these negotiations did not lead to any actual deal.

License production and Finnish made Suomi M/31 submachine guns in other countries:

Swedish versions:

M/37: Version manufactured by Husqvarna factory under license. Chambered to same 9 mm x 20 Browning Long cartridge as Swedish Army standard sidearms FN M/03 and Husqvarna M/07 of that time. 56-round box magazine was used with this weapon. Only small number manufactured before Swedes decided to favour 9 m x 19 cartridge.

M/37-39: Version manufactured by Husqvarna under license. Chambered to 9 mm x 19 Parabellum/Luger cartridge. Replacing earlier M/37 in production it was manufactured from 1939 to mid 1940's. The Swedes also exported this version to Norway, Denmark, Indonesia and Egypt. When compared to Finnish Suomi M/31 the Husqvarna M/37-39 has very different kind of stock with low-gradient pistol grip-part, shorter (23.1-cm) barrel, shorter barrel jacket and simplified sights. Length of the whole weapon was 77 cm and it weight some 3.9 kg empty (or 4.9-kg with fully loaded magazine). The Swedes used these with the same 50-round box magazines that also the Finns manufactured during World War 2.

M/37-39F: Original Suomi M/31 submachine gun manufactured by Tikkakoski imported from Finland. All of these were identical to early version of Suomi M/31 used by Finnish military, in other words: they did not have the muzzle brake. Swedish military used these first with 50-round and later also with 36-round box magazines (similar to the ones used in Finland and in case of 36-round magazine also in Swedish Carl Gustav M/45 submachine gun).

Danish versions:

M/41: Small number of Finnish Suomi M/31 submachine guns had been exported to Denmark already before World War 2. During World War 2 Madsen and Hovea started manufacturing their copy of Suomi submachine gun called M/41. The Danish production went (at least originally) to Danish Army, which the Germans did not disband and disarm until October of 1943. By that time at least 1,400 submachine guns M/41 had been manufactured. After disarming of Danish Army the weapons seem to have went to German use and they may have issued some to their local collaborators. The main differences of original Finnish M/31 and its Danish made copy are in neck area of the weapons stock and in its front sight (M/41 had protective blades in sides of the front sight).

PICTURE: Swiss Mp.43-44 submachine gun with 50-round box magazine. This was the de facto standard magazine type, which Tikkakoski delivered with the Suomi M/31 submachine guns, that it exported during World War 2. Notice differences in front part of the barrel jacket, if compared to Finnish M/31. (Photo provided by 'Gerd Haflinger'). CLICK THUMBNAIL TO SEE LARGER PIC (107 KB).

Swiss versions:

Mp.43: November of 1942 the Swiss signed contract purchasing 5,000 Mp.43 submachine guns, as they called Suomi M/31, made by Tikkakoski and imported to Switzerland from Finland. It seems that The Swiss did not get quite all of these, because quite naturally deliveries to Finnish military were priority for Tikkakoski. All of these were similar to early model of Suomi M/31 used by Finnish military, in other words - the version without the muzzle brake.

Mp.43-44: However the contract signed in November 1942 included also a manufacturing license, which the Swiss put to good use. Hispano-Suiza factory utilised it by manufacturing estimated 22,500 submachine guns Mp.43-44 (as this version is known in Switzerland). When compared to Mp.43 the Swiss Mp.43-44 had a simplified rear sight, which had L-shaped head. This L-shaped head in rear sight could be switched to two positions - one set for 100 meters and another for 200 meters. The barrel length of M/43-44 was about the same as in Finnish M/41 and also other dimensions of this version seem very similar to non muzzle brake equipped version of Finnish M/31.

Soviet versions:

KF-42: During Continuation War a small number Suomi submachine gun M/31 copies in 7.62 mm x 25 calibre were manufactured in Leningrad. The Soviets called this unlicensed copy KF-42 (Karelo-Finskij 42).

PICTURE: According popular phrase imitation is the most sincere form of flattery. This rare Soviet KF-42 submachine gun was a cheaper and easier to manufacture unlicensed version of Finnish Suomi M/31 submachinegun. (Photo taken in Sotamuseo). CLICK THUMBNAIL TO SEE LARGER PIC (49 KB).

Unlike some sources have claimed Finland never acquired any of the license-made Suomi submachine gun versions and none of them saw any use with Finnish military. Only possible exception to this rule might be (likely very small number) of Husqvarna M/37-39 Swedish volunteer unit (SFK) might have brought among its weaponry to Finland during Winter War. As SFK left its weaponry to Finnish military after that war few M/37-39 might have seen Finnish use during Continuation War. At least some of the weapons delivered to Croatia (and possibly Bulgaria) seem to have ended to German hands during the war.

Writer's personal experiences concerning shooting Suomi M/31 submachine gun: As to be expected, the first impression tends to be how surprisingly heavy this weapon is - due to the extremely robust structure with milled steel parts. Especially the version with muzzle brake is also quite muzzle-heavy. Due to these reasons recoil is minimal. The muzzle climb still exists while shooting on full-auto mode, but considering the high rate of fire it is yet easily manageable and therefore the weapon is easy to control. Accuracy is remarkable to submachine gun firing 9 mm x 19 cartridge - in semiauto mode hitting man size target with each shot from distance of 150 meters is normal. From 50 meters keeping torso-size four falling-plate type targets down simultaniously until running out ammunition proved easy. Hitting all four targets with one long burst proved not too difficult either. Sight are simple but effective and aiming fast & simple. Triggers feel seem to be relatively heavy, but it is two-stage and the 'step' is quite obvious. Old magazines are weakest part of the design - while 70-round drum magazines tend to be extremely reliable, they are difficult to fill with ammunition. 50-round box magazines are impossible to fill with ammunition without a proper tool anywhere near to full capacity, but once proper tool and technique are used, are rather easy to use. Obviously 36-round box magazine is both easy to fill and use. Typically just about any individual magazine will work in any individual weapon without a hitch - but there are exceptions to this rule. Reliability seems to be on par with the reputation. Shortly said - this is one of the few World War 2 era small arms, which I would not mind possibly using as a combat weapon even today.