PICTURE: 20-mm Oerlikon M/23 antiaircraft-gun on its fixed mount. This was one of the early versions of 20-mm Oerlikon, which unlike late versions was apparently manufactured only in quite limited numbers. (Photo taken in Ilmatorjuntamuseo). CLICK THUMBNAIL TO SEE LARGER PIC (176 KB).

The surviving gun is 20 mm x 100 RB caliber, but some of the guns were chambered in older 20 mm x 72 RB caliber.

German Reinhold Becker had patented 20-mm automatic cannon already in year 1913. During World War 1 Germans tried introducing it as zeppelin weapon, but as it proved too unreliable it was re-issued as antiaircraft-gun in 1917. However, unreliability of Becker cannon continued also in antiaircraft-gun role making less than successful. After the war Becker sold his patents to Swiss company SEMAG (Seebach Maschnenfabric AG). SEMAG further developed the design and managed sell first of the improved the guns, but failed to reach commercial success. Hence it did not succeed to enjoy fruits of its development work before going bankrupt in year 1921. The SEMAG company was sold and changed name in to Oerlikon AG year 1925. Oerlikon continued developing and manufacturing the gun and started gaining success. The Swiss themselves were first to adopt Semag-Becker of Semag-Oerlikon,as the gun was known, to use of their military in year 1923 (hence the year-number in Finnish name). Later versions of 20-mm Oerlikon guns became one of the most widely used 20-mm antiaircraft-guns before and during World War 2. This was due to later versions being exported to large number of countries and the same time license produced in USA and Great Britain in huge numbers. 20-mm Oerlikon gun was large-scale commercial success before and during World War 2. Nowadays the company (now known as Oerlikon-Contraves) is one of the most well known developers and manufacturers of antiaircraft-guns.

PICTURE: 20-mm Oerlikon M/23 prepared for direct fire use with Finnish soldiers sometime in pre-war era - likely from 1920's. (Original photo part of Jaeger Platoon Website photo collection - unlicensed use of photograph prohibited). CLICK THUMBNAIL TO SEE LARGER PIC (155 KB).

Finland was among the first customers of these guns when it bought four guns from SEMAG in October of 1924. The guns were delivered to Finland in summer of 1925. While they were the version referred as Oerlikon L, some of these guns may have been chambered for older 20 mm x 72 RB ammunition. Early on the Finnish military found the guns problematic, but once the proper methods were developed their reliability proved satisfactory. However, so little ammunition had been bought with the guns that almost all ammunition was spent already in test firing event, which must have been a limiting factor when it came to training gun crews or how useful the guns were in general. What is known also raises questions concerning if Finnish Army even originally intended the guns to be used anti-aircraft weapons. Period photos show that at least one of the guns saw use with gun mount best described as ground support or anti-tank gun mount and what is known the fixed column/cone gun mounts for anti-aircraft use and anti-aircraft sights were presumably acquired in early 1930's.What is known the gun mounts column/cone mounts were Finnish-manufactured, while anti-aircraft sights were bought from Oerlikon. While early on used by Finnish Army, they were at some point transferred to Civil Guard (Suojeluskunta). At that time Finnish Army had no automatic cannons, so it was unusual for such a modern guns to be transferred to Civil Guard, but this may have been explained by lacking equipment and shortage of ammunition. No real actions seem to have been made in the matter before year 1933, at which point acquisition of new gun mounts and sights was set in motion. Archive documents indicate that the than the fixed column/cone mounts were delivered to Kiviniemi Civil Guard in January of 1935. Due to additional purchases of ammunition made in 1933 and 1936, when Winter War started in November of 1939, there were 3,145 rounds for these guns and they could be issued for the war. During Winter War 20 ItK23 guns were issued to light antiaircraft-gun battery, which in December and most of January was used to defend one town after another in Carelian Isthmus . The light anti-aircraft battery was credited for downing four and damaging 13 enemy aircraft. Late January of 1940 the guns was transferred to Finnish Air Force. They served as antiaircraft weaponry in several military airfields until end of Winter War. No information about their later fate exist. One of the guns have survived as in collections of Finnish Anti-Aircraft Museum.

PICTURE: Another view to 20 ItK/23. (Photo taken in Ilmatorjuntamuseo). CLICK THUMBNAIL TO SEE LARGER PIC (56 KB).

PICTURE: 20-mm Madsen M/39 anti-aircraft on universal gun mouunt seen from the front. Finnish Army know this version as 20 ItK/42 M, while Navy called it 20/60 M42 M. The three rods which are also towing beam parts are opened to form a tripod from which the gun shoots. (Photo taken in Jalkaväkimuseo). CLICK THUMBNAIL TO SEE LARGER PIC (166 KB).

(*) Rate of fire varies considerably from one source to another. Ammunition used in was probably a large factor in this. Most sources seem to indicate maximum cyclic rate-of-fire being around 400 shots/minute, but some suggest 350 - 400 or 500 shots/minute. Anyway, due to overheating-problem the gun was rarely used with maximum rate-of-fire for any duration.

Armour penetration: For information about armour penetration capability of this gun see 20 PstK/40, which was antitank/ground support version of this automatic cannon. The actual gun was similar and so were the ballistics - including armour penetration of their ammunition.

PICTURE: Closer look to 20 ItK/39M on universal mount. Photographed on Klimetskoi Island near city Äänislinna / Petroskoi / Petrozavodsk in July of 1942. Photograph taken by E. Nurmi. (SA-kuva photo archive, photo number 98307). CLICK THUMBNAIL TO SEE LARGER PIC (89 KB).

This 20-mm gun was development based to earlier Madsen machineguns developed by Madsen factory (Dansk Industri Syndikat, Compagnie Madsen) in Denmark, introduced year 1926 and become commercial success in 1930's. Besides being manufactured in Denmark, it was also manufactured under license in Belgium and France before World War 2. It was select-fire recoil action automatic gun capable both to semiautomatic and full automatic fire. The weapon had several mount options, including both several fixed models fixed (model 1940 for the Army, model 1936 and model 1939 for the Navy) and mobile (model 1937 and model 1942) versions for antiaircraft- and ground support purposes. Madsen gun was popular in many roles, from these the antiaircraft-gun use was the most common, but guns were also used in antitank-guns, beach defence and ground support roles. In these roles they were also used in aircraft and armoured vehicles. Among countries using 20-mm Madsen guns before or during World War 2 were Denmark, Sweden, Finland, Norway, Estonia, China, Czechoslovakia, Poland, Belgium, France and Germany. During World War 2 they were commonly used by German Kriegsmarine.

The Finns had been aware and interested of 20-mm Madsen already early on. February of 1929 Aimo Lahti and Major A.K. Söderberg had participated to its test shooting in Denmark. They discovered that the weapon was otherwise good, but was somewhat picky when it came to ammunition - ammunition used in tests was not as precisely manufactured as it should have been and this with rimmed cartridge case design used at that time caused malfunctions, making the gun unreliable. The ammunition used in those tests at that time was apparently rimmed version of the cartridge manufactured by Patronenfabrik Solothurn AG in Switzerland. When Lahti and Major Söderberg made their second visit to the Madsen factory just some weeks later the ammunition had been replaced with non-rimmed version manufactured by Kynoch Ltd and the gun now passed the tests without any major issues.

PICTURE: 20 ItK/39M on universal mount with its tripod opened. Photo taken in Hanko during Continuation War. Photograph taken by (TK-mies?) Öhrnberg. (SA-kuva photo archive, photo number 78999). CLICK THUMBNAIL TO SEE LARGER PIC (125 KB).

Finnish Navy had bought six of these guns already around 1930 - 1931. These first six 20-mm Madsen guns were actually originally called "20 ItK/30 M" (20 mm anti-aircraft gun model 1930) and were placed on column gun mounts. The first two of the guns ordered in year 1930 were acquired for new kind of light and fast patrol boats (vartiomoottorivene - VMV) VMV-1 and VMV-2 and ordered in spring of that year. The other three guns were ordered in July for Finnish Vetehinen-class (~Water Sprite class) submarines (one gun per submarine). However the early guns proved very unreliable, so during Continuation War they were replaced with newer 20-mm Madsen guns. Anyway, that was the early situation with the Navy, but it reflected what was to come. The Army did not get its first 20-mm Madsen guns until during Winter War and even then it had to compete with Navy for getting them. Getting more guns during Winter War proved difficult in general. As Winter War was 105 days long total, much of the equipment ordered during it was only delivered after the war had already ended, but it seems that when it came to Madsen guns this may not have been the only reason why the deliveries were slow. It seems that at that time Denmark was trying to remain neutral in such extent, that it was less than willing to sell military equipment directly to Finland. Hence when Denmark approved to sell 28 Madsen guns to Finland in January of 1940, it was only possible on condition that the guns would be officially sold to Swedish military and delivered to Finland by using Ab Svenska Castra (dummy company established by Finland to Sweden as front of clandestine weapons acquisitions during Winter War) as go-between. From those 28 guns 19 were delivered to Finland in March of 1940 and went to Finnish Navy. Another order 10 guns was also in January of 1940 via K.G. Wåhlstedt. Hence the total number or 20-mm Madsen guns ordered during Winter War was 38 guns. During the war Finnish industry and some communities part in financing acquisitions of anti-aircraft guns - these acquisitions included those of 20-mm Madsen.

PICTURE: 20 ItK/30M on unusual fixed naval mount in pre World War 2 era photograph. Presumably photographed in Muurila live fire training area (and test range). The first two 20 mm Madsen guns acquired for Finnish Navy in year 1930 for its patrol boats VMV-1 and VMV-2 had their guns mounted on this type of fixed gun mount design. (Original photograph part of Jaeger Platoon Website photo collection, unlicensed use of photograph prohibited). CLICK THUMBNAIL TO SEE LARGER PIC (72 KB).

The real large-scale deliveries of 20-mm Madsen to Finland did not happen until after Winter War with August of 1940 being especially busy month. The remaining 9 guns from the purchase of 28 guns made during Winter War arrived month and so did the first batch of 50 guns belonging to order made by Finnish Ministry of Defence in February of 1940. This order was for 100 guns and included option for additional 50 guns. The reason behind pile-up of deliveries to August of 1940 was Germany occupying Denmark 9^th of April 1940. Once the Germans occupied Denmark they immediately stopped the deliveries, which did not resume until August of 1940. Guns delivered after Winter War (11/1939 - 3/1940) but before Continuation War (6/1941 - 9/1944) included also 15 guns bought by Committee of Danish Volunteers (Komitéen for danska Frivillige i Finland) during Winter War. In addition Finnish military received unknown number of 20-mm automatic cannons equipped with fixed naval gun mounts, which had been financed with donations gathered in Denmark during Winter War, these particular guns were equipped with plaques informing about the matter. By mid June 1941 Finnish military had received over 200 Madsen automatic cannons. According inventory listing made August of 1941 at that time Finnish military had 240 of these guns, from these Navy had 139 guns, field army had 76 guns, anti-aircraft districts had 10 guns, railway troops had 9 guns and home front troops 6 guns. November of 1942 Finnish Navy made additional order of 121 guns, which were delivered in 1942 - 1943. The total number of 20-mm Madsen guns used by Finnish Armed Forces (Army, Navy etc.) had climbed to about 330 guns in March of 1943, from these 211 gun served with Finnish Navy. The variety of gun mounts that these guns were issued with was quite crazy - 20-mm Madsen guns used by Finnish military got issued with about about dozen gun mount designs. During Continuation War guns in addtion of Navy ships also saw use with coastal troops, coastal artillery, fortification artillery units, anti-aircraft troops, railway troops and home front troops. Finnish Navy hardly hardly had a class of boats or ships without 20-mm Madsen being used on them at one point or another. Boats and ships of all sizes from small VMV patrol boats to gunboats, submarines and large coastal defence ships had them among their weapons. Four of the guns saw use in Finnish railway antiaircraft-batteries (in other words: Finnish armoured trains of that time) around 1943 - 1944 with much larger number of guns being installed to normal box cars to provide trains near frontline some anti-aircraft defence capability. Few anti-aircraft guns installed on improvised sledge gun mounts saw use as antitank-guns during last weeks of Winter War and Finnish military also used about 20 guns equipped with light field guns as antitank guns called 20 PstK/40 during Continuation War.

PICTURE: 20 ItK/39M anti-aircraft gun installed in box car. The gun mount used in this case seems to be the type used with 20 ItK/30M guns in submarines. During Continuation War Finnish Army used railway carriages equipped with anti-aircraft machine gun or 20mm anti-aircraft gun in this manner to provide some air-defence capacity for trains. Photographed by Private Niilo Helander. (SA-kuva photo archive, photo number 82648). CLICK THUMBNAIL TO SEE LARGER PIC (124 KB).

20-mm Madsen automatic cannons acquired to Finnish military:

Source: 20 mm Suomessa by Simpanen and Pitkänen page 162.

PICTURE: 20 ItK/39M on fixed (column) m/36B naval mount. (Photo taken in Sotamuseo). CLICK THUMBNAIL TO SEE LARGER PIC (165 KB).

With Army and Navy using different naming system, the designations Finnish military used with Madsen guns are quite numerous and confusing. Finnish Army knew two versions of this anti-aircraft gun: Old version (M/39 M) and new version (M/40 M). At the same time Finnish Navy had designations for four versions: Oldest version (20 ItK/30 M - nothing to do with German made 20 ItK/30 BSW of the Army), old version (20/60 M36), new version (20/60 M39) and last version (20/60 M43LT). Both Army and Navy used the version equipped with universal gun mount, which was mobile gun mount suited for both anti-aircraft use and shooting surface targets. Army called this version with universal mount M/42 (or 20 ItK/42 M), while Navy called it 20/60 42 M. When it comes to the guns used by the Army the old version used mostly 40-round drum magazines, but could also use later introduced 60-round drum magazines. However the new version (of Army) could use only 60-round drum magazines (which had been introduced with it). For practical purposes (to avoid getting mixed with 20 ItK/40 VKT antiaircraft-gun) the both versions are listed as 20 ItK/39 M in this webpage. Ammunition of Madsen automatic guns was its own kind (20 mm x 120) and had lower armour penetration than 20 mm x 138 B ammunition used in other 20-mm anti-aircraft guns (with exception of Oerlikon guns) used by Finnish military. However, that was not the worst problem of these guns. The real problems of Madsen gun were reliability issues and over-heating issue which could result accidental discharge or high explosive shells cooking off and exploding while inside breech. This very serious and dangerous problem caused by the gun firing from a closed breech was relatively common especially with older versions. All oldest guns up to 20 ItK/39 left live round to chamber if shooting was paused. About 120 - 150 shots of constant automatic fire was enough to make the weapon dangerously hot and as the gun left live round to chamber when shooting was paused, the resulting danger was fairly obvious. High explosive ammunition cooking off in cartridge chamber caused large number of accidents during the war and after it. Various methods were tested to solve the problem, but no real solution was found until modifications introduced for these guns. These modifications introduced at that time added the guns a safety feature which left the breech open if firing was paused. At the same also gun also gun carriages of these guns were modified to be similar as in the newer guns. The modified guns were re-named accordingly - 20 ItK/36-44 M (Army) / 20/60 M36-44 LT (Navy) and 20 ItK/39 M (Army) / 20/60 M39-44 LT (Navy). While the guns acquired during Winter War were already much better reliability-wise than the ones bougth in early 1930's, the reliability issues still also appeared now and then with them.

PICTURE: 20 ItK/39M on fixed (column) m/43 naval mount. (Photo taken in Forum Marinum). CLICK THUMBNAIL TO SEE LARGER PIC (170 KB).

20-mm Madsen automatic cannons that arrived during Winter War were mostly delivered with ammunition manufactured by British manufacturer Kynoch Ltd (part of ICI, Imperial Chemical Industries). But the amount of delivered ammunition with the gun seems to have been limited and acquiring more ammunition from Kynoch proved problematic. Finland has ordered 500,000 rounds of this 20 mm x 120 Madsen ammunition from Kynoch during Winter War, but the delivery of this order had not yet happened when Winter War ended and Kynoch did not accept Finnish orders after it. Hence Finnish military was starting to run low on 20 mm x 120 ammo in late 1941. Starting year 1942 Finnish industry started manufacturing this ammunition with Tikkakoski becoming its main manufacturer and Oy Ammus manufacturing it in smaller scale. Tikkakoski manufactured HE/HE-T and AP-T ammunition in this caliber while Oy Ammus manufactured HE-T and APC-T ammunition. Finnish military used also some AP-T and AP-T ammunition made by Dansk Industri Syndikat. In addition HE-T ammunition manufactured by Oerlikon and German-made AP-T ammmunition were bought from Germany during Continuation War.

Ammunition that Finnish military used with 20-mm Madsen automatic cannons included:

Madsen guns Finnish military used as antiaircraft-guns had simple linear ring-sight, which was just used in approximate aiming before firing the gun. Once the gunner actually started shooting he corrected his aiming according tracers. Typically Finnish military used 3 - 4 man crews with Madsen guns: Gunner, gunners assistant (who changed magazines) and one or two ammunition men who took care of reloading the magazines.

PICTURE: This 20-mm Madsen twin mount gun was one of a kind for Finnish military - As far known this was the only example of such twin gun design in Finnish use. The gun was used on afterdeck of auxiliary gunboat Aunus, which operated in Lake Laatokka / Ladoga during Continuation War. The was apparently captured ship whose Latvian ship crew had called it Ilka and was used to transport soldiers, equipment and supplies mainly to coastal artillery units of Lake Laatokka / Ladoga. Photographed by Lieutenant Pekka Kyytinen. (SA-kuva photo archive, photo number 113265). CLICK THUMBNAIL TO SEE LARGER PIC (113 KB).

20-mm Madsen remained in use of Finnish Navy for a long time after the war. In 1960's Finnish Navy experimented raising their rate-of-fire, but this failed, as it also increased their unreliability considerably. When at the same time the old wartime stocks of 20 mm x 120 ammunition also started giving signs being of way beyond best before date, Finnish Navy decided to replace them with new guns. Finnish Army declared Madsen obsolete in 1970's, but Finnish Navy still kept large number of 20-mm Madsen until 1980's. According inventory list made year 1982 at that time Finnish Navy inventory still included 217 of 20-mm Madsen automatic cannons. In late 1980's also the Navy declared 20-mm Madsen obsolete and got rid of them.

PICTURE: 20 ItK/30. Probably staged photo, since usually these guns were usually dug in better for protection. Photo taken near Viipuri in August of 1941. Photographed by 2^nd Lieutenant Pentti Nikulainen. (SA-kuva.fi photo archive, photo number 40580). CLICK THUMBNAIL TO SEE LARGER PIC (221 KB).

PICTURE: 20 ItK/38 anti-aircraft gun. Photograph taken by Military Official Eero Troberg in Karvala September of 1941. (SA-kuva.fi photo archive, photo number 53274). CLICK THUMBNAIL TO SEE LARGER PIC (194 KB).

distance	hitting angle	penetration
100 m	70 degrees	28 mm
200 m	70 degrees	25 mm
300 m	70 degrees	22 mm
400 m	70 degrees	20 mm
500 m	70 degrees	18 mm
600 m	70 degrees	16 mm
800 m	70 degrees	13 mm
1000 m	70 degrees	10 mm
1500 m	70 degrees	6 mm

PICTURE: 20 ItK/38 with fixed cone-like naval mount. According original photo caption this gun served as low-altitude defense weapon for 78^th Heavy Anti-Aircraft Artillery Battery. Photo taken by Captain Leo Vepsäinen in Kotka October of 1944. (SA-kuva.fi photo archive, photo number 167376). CLICK THUMBNAIL TO SEE LARGER PIC (158 KB).

Versailles treaty had first forbidden antiaircraft-guns from Germany and later only allowed it very limited amount of antiaircraft-guns, but the Germans had bought and developed them in secrecy anyway. But still, the antiaicraft-guns that they had were not substantially numerous or suitable for the large air-defence that their fast growing military forces needed. In 1932 limitations of Versailles treaty were set aside and German military started pouring money into developing new weaponry. One of the weapons they needed was new 20-mm antiaircraft gun. Rheinmetall company developed their Flak 30 gun from earlier Solothurn design and design work was ready already in 1933. Year 1934 arming of German antiaircraft-artillery units with them started. Germans battle-tested Flak 30 in Spanish Civil War and the gun proved also suitable against ground targets in there.

PICTURE: 20 ItK/30 with Finnish post-war pendilum-sight. (Photo taken in Ilmatorjuntamuseo). CLICK THUMBNAIL TO SEE LARGER PIC (147 KB).

In late 1930's Germans started doubting if Flak 30 was effective enough with new aircraft becoming ever faster. So, they decided that new 20-mm gun with faster rate-of-fire and improved aiming was needed. That new gun was Flak 38 developed by Mauser from earlier Flak 30. Flak 38 had not only considerably larger rate-of-fire, but also more precise aiming system in which gears allowed several aiming speed settings for aiming wheels (while aiming wheels of Flak 30 had only one speed). At the same time Mauser managed to drop 30-kg off from weight of the weapon. The somewhat ironic part is that German troops often preferred older Flak 30 as it was more stable, its simpler aiming system left less chances for error and lower rate-of-fire gave more time for correcting fire before reloading. Flak 38 was introduced to use of German Armed Forces in 1939. Both 20 mm Flak 30 and Flak 38 proved quite successful in German hands during World War 2 and lead to further designs, from which specially the four-barrel Flakvierling-versions were produced in considerable numbers. The Germans manufactured over 18,000 Flak 30 and Flak 38 by end of 2^nd World War. Mobile versions of both AA-guns were transported by attaching them to special trailer called "special trailer 51", guns installed to trailer could be used to engage ground targets but no air targets (traverse could not be used while the gun was attached to trailer).

PICTURE: 20 ItK/38 in special trailer 51. Anti-aircraft sight is missing and the trailer has reflectors added post-war because of Finnish traffic legislation. I just wish that the museum would have enough buildings to keep this sort of jewels indoors. (Photo taken in Ilmatorjuntamuseo). CLICK THUMBNAIL TO SEE LARGER PIC (227 KB).

Finnish military named Flak 30 as 20 ItK/30. Finland had managed to order 134 of these guns in October of 1939 (just few weeks before Winter War). The first shipment of 30 guns also arrived just days before starting of Winter War. The treaties Germany had made with Soviet Union forbid it selling war-materials to enemies of the Soviets or assisting them otherwise - and at that time Hitler's German followed this treaty. So, when Winter War started the Germans ended the shipments of these guns after that first delivery. To the Finns the situation was terrible: They had large number of antiaircraft-artillery units without weapons and when European armies were arming themselves getting modern weapons from elsewhere was almost impossible. Since the official channels of delivery were closed decision was made to try getting the undelivered guns by using more covert methods: Dummy company "Ab Svenska Castra" with friendly Swedes seated to its leadership was swiftly established to Stockholm (Sweden). Negotiations were also started covertly with the Germans. During first days of December 1939 Finns secretly negotiated with the Germans in Berlin. These negotiations lead to result - the Germans accepted to deliver more guns if Sweden would be portrayed as customer country buying them and if the Finns would pay the weapons with wood and copper, which German war-industry needed. This covert deal wasn't long lasting because the information about the deliveries of Italian Fiat G.50 fighter aircraft through German territory soon leaked to Swedish press, as the matter got to Swedish newspapers, soon also the Soviets got alarmed that the Germans were not strictly following German - Soviet treaty. 9^th of December Germany received note of protest from Soviet Union and this ended the whole Finnish-German covert arrangement. While the Germans replied the note of protest by denying its allegations, they also were unwilling to risk matters further and again stopped the deliveries - this time for good. Equipment that the Finns had succeeded convincing the Germans to send forward during those few days of early December included the second shipment of 20 guns 20 ItK/30. This was the last delivery of German anti-aircraft guns to Finland during Winter War and rest of the 20 ItK/30 anti-aircraft guns were never delivered.

After Winter War Germany changed its policy towards Finland. It was again willing to sell weaponry to the Finns. In this situation Finland ordered Flak 38 guns, which Finnish military named 20 ItK/38. The exact number of 20 ItK/38 anti-aircraft guns delivered to Finland remains uncertain at this time. Existing sources indicate that their number may have been in between 93 and 113 guns. The uncertainty seems to concern number of guns delivered in 1944 and does not fit to shipping manifestos existing in archives. According shipping manifestos year 1944 Finnish military received 56 of these anti-aircraft guns - 16 mobile (towed) guns and 40 guns fixed mounts. According them last ships to deliver them were 10 mobile guns + 25 fixed guns with "Greta Thorden" (19th of August 1944) and 15 fixed guns with "Capella" (25th of August 1944). Mobile (towed) guns went mostly to Field Army, while fixed guns were were acquired for Navy and Coastal Defence, but some seem to have also been issued from anti-aircraft units of home front. Fixed guns delivered in 1944 were apparently equipped with socken lafette LC 30 fixed gun mounts. The Finns often called German 20-mm guns BSW-guns or Gustloff-guns after their manufacturers Berliner Suhl Werke (BSW) and Gustloff-Werke (Gustloff).

German 20-mm AA-guns delivered to Finland according various sources:

Older Finnish publications:

20 mm Suomessa / 20 mm in Finland:

PICTURE: 20 ItK/30 anti-aircraft in Kollaa during Winter War. Notice snow camo on gun and soldiers. Photographer unknown. (SA-kuva.fi photo archive, photo number 5206). CLICK THUMBNAIL TO SEE LARGER PIC (128 KB).

20 ItK/30 was the main light antiaircraft-gun in Finnish use during Winter War. In that war it proved excellent weapon: Finnish 20-mm antiaircraft-guns shot down 104 Soviet aircraft during Winter War and spent only average 474 shots/shot down plane. In Continuation War the average amount of shots needed for shooting down aircraft climbed as aircraft speed increased, but 20-mm German-made guns still served Finnish military well. Finnish antiaircraft-gun crews typically considered German 20-mm cannons to have excellent quality, accuracy and reliability (Only exceptionally cold winter of 1939 - 1940 combined with lack of suitable lubrication caused some reliability problems for them, but that winter was ever more difficult to other antiaircraft-guns in Finnish use). All the 142 guns survived World War 2 and after the war they remained first in active use (probably until early 1960's) and were then warehoused for reserves until 1990's. Due to jet propulsion the maximum practical speed for aircraftchanged considerably after World War 2. The new jet planes were too fast to the sights that Germans had originally equipped these guns with, so Finnish military equipped them with new pendulum annular sights in post-war era.

PICTURE: 20-mm Breda M/35 anti-aircraft gun. Notice the loading strips. Photo taken by Captain E.J. Paavilainen in Rukajärvi September of 1941. (SA-kuva.fi photo archive, photo number 47556). CLICK THUMBNAIL TO SEE LARGER PIC (149 KB).

Italian 20-mm Breda M/35 cannon was basically enlarged version from earlier Breda machinegun. The gun was designed as dual-use weapon from the start: It was intended both as antitank- and antiaircraft-weapon. Italian military introduced the gun to their use in 1935. The mount, which was basically a compromise because of needs for it to fit to both roles proved not so good for antiaircraft-role. It was not one of the most stable or rigid and its low height meant that the gun could not be dug deep to ground (low dug fire position did not give cover to guns crew). From technical point of view the weapon was gas-action automatic with gas-piston and capable only to automatic fire. However its rate of fire was adjustable. Technically the weapon in principle was capable firing even 500 shots/minute, but in reality the rate of fire was adjusted much less. The gun had two sights: Reflector sight with predictor for air targets and ground-sight for surface-targets. The reflector sight had range-disk with setting 0 - 3000 and its predictor had settings for target speeds in between 0 - 550 km/h. The ground sight had setting ranging between 0 - 3000 meters for every 100 meters. The loading system used in 20-mm Breda was the same mechanically overly complicated one as in Breda-machinegun, meaning that it loaded spent cartridge cases back to loading strips. However, loading system also allowed feeding in ammunition strips strip after strip, so stopping firing for reloading was not necessary if low rate of fire was used. For transporting the gun a two-wheeled trailer was used. 20-mm Breda was not exported in any real numbers before World War 2, but they did saw use in Spanish Civil War. During World War 2 captured guns were used by at least Australians, Greeks, British and Germans.

PICTURE: 20 ItK/35. Legs of the tripod-mount are removable. When the gun was readied for transport the legs were removed and tires attached. (Photo taken in Ilmatorjuntamuseo). CLICK THUMBNAIL TO SEE LARGER PIC (66 KB).

During Winter War the Finns had terrible shortage of antiaircraft-guns and the Italians were willing to sell those. So the Finns bought first 28 guns from Italy in December 1939 and another 20 bit later, but the Germans managed to delay delivery of those 48 guns until February of 1940. The 48 guns ordered during Winter War cost 468,000 USD total. After their arrival the guns were issued to Finnish antiaircraft-artillery units in February - March of 1940 and some had not yet been issued when Winter War ended in 13^th of March 1939. During Interim peace Finns bought additional 40 guns, which were delivered before starting of Continuation War- bringing the total number of 20 ItK35 Br in Finnish use for start of Continuation War as 88 guns. Also four Italian MAS motor torpedo boats, which Finland bought in summer of 1942 and renamed Jymy-class, each had one fixed 20 mm Breda M/35 antiaircraft-gun. During Continuation War VKT (Valtion Kivääritehdas = State Rifle Factory) manufactured spare parts and spare barrels for these guns.

PICTURE: 20-mm Breda M/35 anti-aircraft gun being manhandled by its crew into immediate frontline. Because 20 ItK/35 was so much lighter than other mobile 20-mm anti-aircraft guns, from these guns it was most commonly used for direct-fire fire support in the frontline. Photo taken by Captain E.J. Paavilainen near Pismajoki River in September of 1941. (SA-kuva.fi photo archive, photo number 47564). CLICK THUMBNAIL TO SEE LARGER PIC (134 KB).

During Continuation War Finnish military lost 5 of these guns in battle. They proved fairly good in Finnish use: The problems mentioned earlier were evident and specially the reliability was not as good as with other 20-mm antiaircraft-guns, but the guns were still very usable. Ammunition compatibility with German antiaircraft-guns and Lahti antitank-rifles was also a clear plus. Wartime photos indicate that the Finns tested also armour penetration capabilities of these guns and sometimes also used them against ground targets. Even if the gun had two-wheeled trailer Finnish soldiers often transported 20-mm Breda on truck instead of towing it. Reason for this was in the guns structural weakness - it could not be safely towed faster than 20 km/h and even then towing the gun behind a truck was recommended only for short distances. Besides motorised towing the gun could also be towed with horse or even pulled by its crew (for short distances only). The gun magazine holster coming with the gun contained four magazines. Using 20-mm Breda gun against air-targets was fairly complicated and so Finnish Army used six-man crews with them. One man was commanding the whole gun, one took care of aiming, one set the range-setting, one set the flight-direction, one took care of reloading the gun and the last man took care of carrying more ammunition to the gun. After World War 2 the some of the remaining guns were used as training weapons for AA-gun crews for antiaircraft-gun units of infantry and the rest warehoused for possible wartime use they were until replaced with more modern weaponry. Year 1960 still 79 of the mobile guns and all the 4 fixed guns remained. Finnish military declared 20-mm Breda guns obsolete in mid 1980's

PICTURE: 20 ItK/40 VKT antiaircraft-gun. Photo taken by Military Official Göte Vainio in Uuksu, July of 1944. (SA-kuva.fi photo archive, photo number 157800). CLICK THUMBNAIL TO SEE LARGER PIC (163 KB).

Armour penetration:

"Military manual, 20 ItK/40 VKT2 kalusto-ohje" (AP or AP-T round):

distance	hitting angle	penetration
300 m	60 degrees	20 mm
500 m	60 degrees	16 mm

This antiaircraft-gun designed by Aimo Lahti was based to 20-mm L-39 antitank-rifle, which Lahti had designed earlier. It was manufactured by VKT (= Valtion Kivääritehdas = State Rifle Factory) factory owned by Finnish state. It also proved to be best of 20-mm AA-guns in Finnish use during World War 2. Mount of the gun had two full-automatic gas-action cannons with 20-round magazines of their own installed side-by-side on relatively light gun mount. Adjustable rate of fire with two barrels gave it much better firepower than other antiaircraft-guns commonly in use of Finnish Army at that time. The 20-round magazine weight some 5.6 kg empty and loaded to full capacity about 11 - 12 kg (depending ammunition used). These magazines came with the gun in boxes each containing four magazines. Gun-sight designed by Engineer Osmo Niskanen and manufactured by Strömberg Company was more complicated to use than sights of German light antiaircraft-guns developed around the same time, but worked well with properly trained gun-crew. Two-wheeled trailer was used for transporting the weapon. It had been designed for motorised towing, but only on road as the trailer offered only 20-cm ground clearance. Maximum towing speed was around 30 - 40 km/h. However this towing speed proved somewhat unrealistic due to the structural weakness of towing and trailer, which made it rather frail. Also gun barrels were more difficult to replace with new ones than in other antiaircraft-guns of this calibre used by Finnish Army. Unlike L-39/44 antiaircraft-rifle this weapon had been designed as full automatic from the start and the strengthened structure had durability needed for of full-automatic fire.

PICTURE: 20 ItK/40 VKT anti-aircraft gun seen from another side. Photo taken by Military Official E. Nurmi in Loimola, August of 1944. Notice wartime sights.(SA-kuva.fi photo archive, photo number 159692). CLICK THUMBNAIL TO SEE LARGER PIC (155 KB).

First prototype of this anti-aircraft gun was heavily based to L-39 antitank-rifle, for developing of which Aimo Lahti had worked since year 1934. That prototype had been ordered from VKT already in 3rd of May 1939 and had been test-fired first already before Winter War in October of 1939. Finnish Air Force had also placed the first order for 50 guns known at that time as anti-aircraft gun L-39 already in January of 1940, but the guns that were ultimately delivered several years later were considerably different from this early prototype. One might wonder why the delivery got delayed with several years. It was not only that VKT had rather limited production capacity and Weapons Design Committee getting mixed in matter with its "supervision and guidance" plus heated argument that Aimo Lahti had with Colonel Raatikainen (Head of Weapons Design Committee and head of Ordnance Department in Ministory of Defence / Finnish Armed Forces GHQ) about new higher gun mount may have caused additional delays, but also acquiring of the Zeiss Ned 4 A gun counter / predictor sight chosen as its gun sight in year 1939 proved impossible. Apparently first prototypes used 20 mm x 113 ammunition and only later prototype versions manufactured in 1939 - 1940 were made in 20 mm x 138B caliber. This change of caliber happened due to order of 20 ItK/30 anti-aircraft guns made to Germany in year 1939 and was introduced to allow use of same ammunition in both gun types. Even if none of the guns still known as anti-aircraft gun L-39 had been yet delivered to Finnish military, in spring of 1940 Finnish Air Force placed additional order of 120 guns. At that time VKT was so swamped with its already existing duties as major military small arms repair facility and small arms manufacturer, that it ordered manufacturing of certain parts needed for these guns from other Finnish factories. Even then the first "mass-produced" guns now renamed as 20 ItK/40 VKT were not completed until year 1943. These parts that VKT ordered from other manufacturers included gun mounts, from which Mikro Oy manufactured 50 and Rosenlew works in Pori 120. From the 170 guns ordered by Finnish Air Force 155 guns were delivered in year 1943 and the remaining 19 guns in 1944. Small number of guns were also manufactured after World War 2, with the total production of 20 ItK/40 VKT being about 200 guns. Due to German Zeiss Ned 4 A predictor sights not being available, gun sights were ordered from Finnish company Oy Strömberg Ab, which delivered its own gun sight design for all wartime 170 guns. After World War 2 Strömberg sights were replaced with simpler pendulum-sights, that were better suited to be used against with new faster jet-propulsion aircraft. Once the completed guns had been finished and test-fired, they got delivered in small batches. Finnish soldiers soon nicknamed the gun as "VeKoTin" (Gadget) by twisting the abbreviation of manufacturer (VKT). The price per gun for 20 ItK/40 VKT was 244,420 Finnish marks.

PICTURE: 20 ItK/40 VKT anti-aircraft gun with post-war pendulum-sight. (Photo taken in Ilmatorjuntamuseo). CLICK THUMBNAIL TO SEE LARGER PIC (203 KB).

When Finnish Armed Forces re-estimated the antiaircraft-weapons left from the war, 20 ItK/40 proved to be only 20-mm anti-aircraft gun, which was still found satisfactory. The guns remained in training use until 1970's and after that were stored for possible wartime use until 1980's.

20 mm Flakvierling: German naval unit operated Siebel artillery ferries in Lake Ladoga starting from 1942. In summer - autumn of 1944 Finns briefly got few artillery ferries of that type to their use. Among weaponry used in those ferries were some 20-mm Flakvierling guns. When Continuation War ended Soviets got the ferries and that was the end for these guns in Finnish use.

20 mm L-34 (version II): Design of Aimo Lahti manufactured by VKT (State Rifle Factory) using 20 mm x 113 ammunition. Series of 12 automatic guns with (column-type) naval mounts were made to Finnish Coastal Guard by VKT (gun barrels were made by Tampella) in 1930's and installed to some of the VMV patrol boats (VMV-boats 8 - 17) of Finnish Navy. When Winter War started the guns were still in use, but because shortage of ammunition suitable for antiaircraft-use (HE-tracer rounds) they could not be really used (20 mm x 113 was Finnish ammunition type not used in any other country) antiaircraft weaponry. This made the guns quite useless in that situation, until more HE-T was manufactured by Tikkakoski starting year 1940 by using Italian-made 150-gram HE-T projectiles. The gun was spring-recoil action automatic cannon with 15-round arch-shaped box magazines. Rate-of-fire was about 350 rounds per minute and muzzle velocity around 830 m/sec. Naval mount allowed 360 degree traverse and almost 90 degree elevation. These guns had only open sights, which were poorly suited for anti-aircraft use. Armour penetration with AP-T round from 300 meters in 60 degree angle was about 17 - 22 mm. Only other weapons using were chambered to the same 20 mm x 113 ammunition were two prototypes of L-39 antitank-rifle. After Winter War Finnish military had again possibility of getting other suitable 20-mm automatic cannons (Danish 20 ItK/39 Madsen for the Navy and German 20 ItK/38 for the Army). In this situation manufacturing 20 mm x 113 ammunition only for these twelve guns would have made little sense, so Finnish Navy started replacing its L-34 guns with 20 ItK/39 Madsen. Before starting of Continuation War 20-mm Madsen guns had already replaced them as main weapon of most VMV-patrol boats, after which they saw use in some other boats and apparently also later on also with coastal artillery.

20 ItK/39T: This was Tampella-manufactured 20-mm automatic guns based to Aimo Lahti's designs. The basic idea seems to have been that Tampella intended to manufacture Lahti's 20-mm automatic cannon L-34 for export and acquired production license for that purpose. These two guns were production prototypes, which Tampella manufactured before Winter War. But since no export deals were ever acquired, the two prototype guns were the only automatic cannons of this type that Tampella ever manufactured. During Winter War Tampella factory in city of Tampere did not have any antiaircraft-weapons for defending it against air raids. So the prototype guns were adapted as antiaircraft-guns for its production facility. Some Suojeluskunta (Civil Guard) members that belonged to its factory workers were selected and trained as their gun crews. Basically the guns were heavily based to L-34 automatic cannon, but had different Tampella designed firing mechanism and annular-sights. Due to requirements set in contract made by Tampella with VKT about production license, some parts used in the guns had been made by VKT. The guns used arched 15-round box-magazines and were chambered to unique 20 mm x 113B ammunition (belted version of Finnish 20 mm x 113 ammunition). The guns served in this use both during Winter War, before being removed from use and stored during Continuation War.

SOURCES:

Raimo Vehviläinen, Ahti Lappi and Markku Palokangas: Itsenäisen Suomen Ilmatorjuntatykit 1917 - 2000 / The Anti-aircraft Guns of Independent Finland 1917 - 2000.

Pekka Kiiskinen and Pasi Wahlman: Itsenäisen Suomen laivaston laivatykit 1918 - 2004.

Alex Buchner: Deutche and allieerte heereswaffen 1939 - 1945.

Terry Gander and Peter Chamberlain: Small Arms, Artillery and Special Weapons of the third reich.

Ian Hogg: Twentieth-Century Artillery.

Chris Chant: Artillery of World War II.

Raimo Vehviläinen: Ilmatorjuntamuseo-opas.

Pekka Kiiskinen and Pasi Wahlman: Itsenäisen Suomen laivaston laivatykit 1918 - 2004.

Pentti Palmu: Yön yli päivään, Suomen Ilmatorjunnan vaiheita 1925 - 1990.

Ilmatorjuntajoukot 1925 - 1960 by E. Peura, Niilo A. A. Simojoki, J. Lapinleimu, O. Ranta, V. Rantalainen and L. Pamppunen.

Ahti Lappi: Ilmatorjunta ilmasodassa 1794 - 1945.

Talvisodan historia series, parts 1 and 4.

Jatkosodan historia series, parts 1 and 6.

Markku Palokangas: Sotilaskäsiaseet Suomessa 1918 - 1988.

Werner Müller: German medium flak in combat - 20mm-88mm FLAK.

Werner Müller: Die leichte und mittlere Flak 1906 - 1945, eingesetzt bei den Waffengattungen an allen Fronten.

Alex Buchner: Deutche und alliierte heereswaffen 1939 - 1945.

Pentti Toivonen: Salpauselän ilmatorjuntapatteristo 1928 - 1988.

Vesa Toivonen: Tampellasta Patriaan (From Tampella to Patria).

Mika Pitkänen and Timo Simpanen: 20 mm Suomessa, aseet ja ampumatarvikkeet ennen vuotta 1945.

Article: Ilmatorjuntatykistömme 1925 - 45 by Jalmari Lapinleimu in Kansa Taisteli magazine vol. 11/1976.

Risto Erjola: Aseiden valmistus Suomessa vuosina 1939 - 1945

Military manual: Ilmatorjuntatykistön Ampumatarvikkeet by Ilmavoimien Esikunta, Ilmatorjunta Osasto.

Military manual: Ilmatorjuntamies 1950.

Military manual: It-joukkojen erikoisohjeita (30th of December 1939) by Ilmapuolustuksen Esikunta.

Military manual: Jalkaväen Ampumatarvikkeet I by Puolustusvoimien Pääesikunta Taisteluvälineosasto (printed 1941, updated until September 1944).

Military manual: 20 ItK/40 VKT2, Kalusto-ohje (1947).

Military manual: 20 mm:n Madsen-konetykin ja lavetin selostus (1941).

Military manual: 20 mm. Ilmatorjuntakanuuna malli Madsen. Kalusto.

Military manual: 20 mm:n konetykki Madsen by Puolustusministeriö (1940)

Military manual: 20 m/m:n Kev.it. tykki M/Breda, Lyhyt kalustoselostus ja harjoitusohje.

Military manual: Ampumatarvikenimikkeistö by Puolustusvoimien Pääesikunta Taisteluvälineosasto (printed 1941).

Brochure: Canon Mitralleur De 20 m/m Tampella Modele Lahti / Canon Mitrailleur 20 m/m Modele L/34.

Finnish military archives, archive reference T19043/20.

Finnish National Archives folder Sk-2513/396 (contains transfer documents for equipment transferred from Finnish Army to Civil Guard).

Special thanks to Ilmatorjuntamuseo (Finnish Antiaircraft Museum), Tuusula.

Special thanks to Sotamuseo (Finnish Military Museum), Helsinki.