As many projects development of Finnish antitank-rifles and antitank-machineguns started with a discussion and an argument. Some officers of Finnish Army wanted 12.7-mm weapon, some wanted 13.2 mm weapon and some (including Lahti) wanted 20 mm weapon. The discussion and argument about the matter divided large part of Finnish officer corps into two camps. Problem with accepting 20-mm weapon early on seems have been mainly the low muzzle velocity that existing 20-mm ammunition allowed at that time. While also 12.7-mm caliber had some support, it remains questionable if any prototypes in this caliber were actually made. The situation with 13.2-mm caliber ammunition is quite different with plenty of testing starting from year 1934. Lahti didn't like neither calibre, as he thought them both to have too little armour-penetration and was also unhappy with that fact that ammunition with tracer was not available for either of these calibers.

As this would not have been enough Lahti got into argument with Colonel Raatikainen of Weapons Design Committee about weapons mount of the new at-rifle. Raatikainen wanted the mount to be similar as the one that the Germans had. The German mount had been planned to be suitable both to antiaircraft- and antitank-use, but Lahti considered it to be unsuitable for antitank-use. Another disagreement surfaced when Raatikainen and Saario (member of Weapons Design Committee) wanted Swiss Oerlikon gun to be approved (according Lahti suspicions about them representing Oerlikon and having personal financial interests in this matter seems to have existed) for this use. Aimo Lahti was very much against this, as Oerlikon gun had low muzzle velocity and because of that poor armour-penetration capability.

Artillery Generals Nenonen and Svanström joined the argument demanding 20-mm AA-rifle capable for penetrating 30-mm of armour. Live fire tests of summer 1939 finally proved that 20-mm ammunition had superior armour penetration when compared to 13.2-mm ammunition. These tests resulted to a decision of choosing 20 mm as calibre of Finnish antitank rifles. But before this lot of time had been lost and time proved to be exactly the commodity, which Finland was about to run out.

Lahti's 13.2-mm machinegun prototypes manufactured included:

• L-34: Could be used both in armoured vehicles and as AT-weapon, first prototype, one prototype made.
• L-35/36: 2 weapons made for Landsverk 182 armoured car. Ultimately the 2nd weapon used for Sisu armoured car.
• L-37: One prototype made with 15-round strips and another with 32-round magazines.
• L-38: One prototype made with 20-round magazine.
• L-39: Two prototypes made for different altenative magazines - 15-round box magazine and 60-round drum magazine. One of these two was prototype of anti-aircraft machinegun with two weapons side by side on the same mount.

All these versions were manufactured in VKT. 13.2 mm L-38 AT-rifle was made 1938 - 1939 and probably also one prototype of L-39 at-rifle was made in 13.2-mm x 118 B calibre. Lahti designed this 13.2-mm prototype of gas-action semiautomatic antitank rifled weight about 25-kg, fired from closed bolt and was equipped with a bipod and alternative 8 and 15 round magazines. Weapons Design Committee had tested already previous year improvised full-auto version build by stripping all non-essensial parts from one of the machinegun-prototypes, but the test results had showed that its accuracy was unacceptably poor, due to being open-bolt firing design.

(*) Ammunition with VKT-made AP bullets. B = belted. Ammunition used was Finnish design, other ammunition of same calibre class used at that time (such as 13.2 mm x 99 Hotchkiss, 12.7 mm x 99 and 12.7 mm x 108) didn't reach muzzle velocities this high. 13,2 mm x 120 B cartridge cases (which had longermounth when compared to 13,2 mm x 118 B) were first tested with experimental bullets. Later Lahti designed 13,2 mm x 120 B cartridge cases apparenty because 13.2 mm x 118 B failed to produce the 1,000 m/sec muzzle velocity, which was had been calculated as high enough for achieving of the required armour peneration. 13.2 mm x 120 B cartridge cases may have been manufactured by D.W.M. in Germany in 1939.

Bullets used in Finnish 13,2 mm x 118 B (and 13,2 mm x 120 B) ammunition:

Some earlier sources mention also Hungarian AP-incendiary bullets, but this information might be incorrect.

The 13.2-mm ammunition was manufactured by VKT (= Valtion Kivääritehdas = State Rifle Factory). Majority of ammunition was loaded with VKT-made made bullets. VKT's armour piercing bullet had steel core and jacket made from tombac (zinc-copper mix). Some ammunition were also loaded with French Hotchkiss bullets delivered by Manufacture de Machines du Haut-Rhin. Domestic 13,2 mm x 118 B cartridge cases (made from brass) were manufactured by Oy Tikkakoski Ab and Oy Sytytin.

When Winter War started Finland had only two prototypes of 20 mm AT-rifle and six 13.2 mm weapons (made 1934 - 1939) to use. Both 20 mm prototypes and three out of six 13 machineguns were used in that war, from these both 20 mm rifles and one 13.2 mm AT-machinegun were used in Metsäpirtti and Taipale area. In those battles 20-mm AT-rifles were found to be very good while 13.2 mm was found to be non-effective. The other two 13.2 mm machineguns served in different uses: One as main weapon of single Finnish Landsverk armoured car and another as anti-aircraft machinegun.

Some quates from reports, which basically resulted burying of 13.2 mm as possible antitank calibre for Finnish use for good (source: Marskin panssarintuhoojat):

• "Shots fired to all points of (Soviet) Light (T-26) tank from distance of (only) 30 metres without any results".
• "13-mm machineguns are as useless as antitank-weapons. They are usually malfunctioning and are easily frozen.".

These experiences made 20-mm calibre only surviving option for Finnish antitank rifle and verified the decision of 20-mm antitank rifle L-39 going to production.

PICTURE: 20 mm at-rifle L-39. (Photo taken in Sotamuseo). CLICK THUMBNAIL TO SEE LARGER PIC (49 KB).

(*) Two prototypes of this at-rifle were manufactured in 20 mm x 113 Lahti calibre. They were used in Battle during Winter War and managed to destroy four Soviet tanks.

Armour penetration:

"Marskin panssarintuhoojat" (AP, 800 m/s):

Theoretical estimate:

distance	hitting angle	penetration
300 m	60 degrees	20 mm
500 m	60 degrees	16 mm
1000 m	60 degrees	12 mm

Test results from live fire tests (made in year 1943):

distance	hitting angle	penetration
300 m	60 degrees	20 mm
500 m	60 degrees	15 mm
1000 m	60 degrees	9 mm

"Military manual, Panssarintorjuntakiväärit":

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

"Military manual, 20 mm:n panssarintorjuntakivääri L/39":

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

Finnish live fire testing year 1943 (AP-T round, 830 m/sec):

distance	hitting angle	penetration
100 m	70 degrees	28 mm
200 m	70 degrees	25 mm
300 m	70 degrees	23 mm
400 m	70 degrees	21 mm
500 m	70 degrees	18 mm
600 m	70 degrees	17 mm
800 m	70 degrees	13 mm
1000 m	70 degrees	10 mm
1500 m	70 degrees	6 mm

Several 20 mm ammunition types were estimated for new 20 mm antitank rifle, among those considered were Madsen and Bofors rounds, but finally 20 mm x 113 ammunition of Lahti's own designed was chosen in 5^th of May 1939. Lahti designed the weapon in three weeks, soon two prototypes were made and tested. Prototypes of 20-mm antitank rifle easily won 13-mm prototypes in tests of summer 1939. 6^th of September 1939 new 20 mm antitank-rifle was accepted to Finnish Army weaponry with name L-39. First order of 410 AT-rifles was made already during that same month. At this point order of German 20 mm antiaircraft guns, which the Finns had made complicated things. The Finns decided to manufacture all further 20 mm antitank rifles in 20 mm x 138 B (Rheinmetall-Borsig / Solothurn long) calibre (to allow same ammunition being used in both AA-guns and AT-rifle) in 2^nd of October 1939. This made ammunition supply obviously much more easier, since ammunition in this calibre was manufactured for example in Germany and Italy, while 20 mm x 113 would have been unique to Finland. However according recent book 20 mm Suomessa... by Pitkänen and Simpanen this was not the only reason. According it the propellant charge, which VKT wanted to use to reach requested muzzle velocity, could not be contained in 20 mm x 113 cartridge case, while 20 mm x 138B cartridge case was large enough for it. Then came Winter War and changed the situation totally - the whole production got delayed as production capacity of its intended manufacturer VKT (Valtion Kivääritehdas = State Rifle Factory) was more urgently needed for other weapons.

So, the manufacturing of L-39 could be started only after Winter War. First pre-production series of 10 L-39 was finished in 10^th of April 1940. Total production was about 1,850. The only manufacturer of L-39 antitank rifle was VKT (Valtion Kivääritehdas = State Rifle Factory) in town of Jyväskylä. During early part of Continuation War L-39 replaced Boys AT-rifle also used in that time little by little. However, in the same time L-39 was getting outdated, as new Soviet T-34 and KV tanks had armour thick enough for them to be practically immune to antitank rifles. But this didn't end the use of L-39, it still was a real threat to lighter Soviet tanks and well-placed shots of good shooter could still damage even heaviest of Soviet tanks. Another reason for keeping L-39 antitank-rifle in use were new uses invented for it: With its AP and HE ammunition it was effective against targets such as bunker portholes and landing crafts up to 500 - 600 meter distance. And when placed on improvised anti-aircraft mount it presented a threat that Soviet ground-attack aircraft pilots had to take under consideration. Finnish troops nicknamed the weapon "norsupyssy" (= "elephant gun") and the weapon got a good reputation for its accuracy.

As mentioned L-39 was gas-action semiautomatic, but it wasn't purely semiautomatic in common sense meaning of the term. When a shot was fired and the bolt retreated back it didn't return forward for next shot until being released with a switch located front part of the weapon's pistol grip. Usually releasing the bolt was done just immediately firing the shot as it reduced the feel of recoil. Mechanism of L-39 was loaded from the crank-like handle located in right side of the weapon. The weapon fired from the closed bolt. Presumably the bolt not returning forward had been added design to improve cooling of the weapon. As usual this antitank-rifle had both bipod and muzzle brake. Amount of gas getting to gas-action mechanism was adjustable (four settings: 1.5, 1.8, 2.2 and 2.5 indicate diameter of hole to gas-action mechanism). Magazines of the weapon were not exactly light either - empty magazine weight 3.37-kg and fully loaded one some 6.7-kg. Experienced shooter could achieve rate of fire as high as 15 shots/minute. The protective arch in front of the trigger guard was there for a good reason - the weapon extracts its used (heavy and hot) cartridge cases below the weapon just in front of it. Sights were fully adjustable with rear sight settings from 200 to 1400 meters. Because of the magazine located on top the weapon the sights were located to left side of the weapon. Typical equipment included four magazine pouches or boxes each containing two magazines - in other words typically L-39 was issued with 8 magazines. Once the anti-aircraft use of these weapons became common during Continuation War simple anti-aircraft mount (allowing the weapon to be attached on head of a pole pointing upwards) were manufactured and delivered for them. Before this happened some of the Finnish troops build improvised mounts suitable for this kind of use.

PICTURE: More detailed look to L-39 antitank rifle. The crank on side of the weapon is cocking lever. (Photo taken in Sotamuseo). CLICK THUMBNAIL TO SEE LARGER PIC (55 KB).

Ammunition types used included AP, AP-T, APHE-T, HE-T and phosphorous shells. AP was most plentiful of ammunition types but not very suitable to some of the later uses for L-39. While Soviet medium and heavy tanks soon became just too heavily armour to be destroyed with this antitank rifle the well-aimed hits of shots could still immobilise tank, damage turning system of turret or do damage to other important tank parts. At the same time AP-T and APHE-T projectiles fired by these weapons were dangerous to even well-armoured Stormovik ground attack aircraft. Well placed shots of HE and phosphorous shells hitting bunker vision slots were used to keep Soviet infantry "entertained" during the long trench war period, phosphorous shells were also favoured for setting forest fires behind Soviet lines during summer-time. However availability of HE, APHE-tracer and phosphorous shells was typically more limited as these ammunition types were mostly used with antiaircraft-guns.

At its largest use of L-39 was just before Soviet attack of June 1944. At that time Finnish troops had 1,789 antitank-rifles L-39. Losses of this weapon were quite large in summer of 1944 as it was too large and heavy for one man to carry it alone long distances. However Finnish military was able to replace the lost weapons quite fast, so when the war ended Finnish troops still had some 1,650 weapons of this type. After the most worn weapons had been scrapped in year 1951 still 1,333 antitank-rifles L-39 remained. Between 1960 - 1961 about 1.000 of the remaining L-39 were sold to United States, where they become popular among collectors. In 1960's Finnish Army got re-interested about AA-rifle as possible anti-helicopter weapon, this lead to remaining L-39 antitank rifles being warehoused until year 1986. That same year most of the remaining 645 weapons were scrapped and some sold to collectors and museums.

Losses of 20-mm antitank-rifles during period 9^th of June - 7^th of July 1944:

(*) While all other 20-mm rifles listed here are quite certainly L-39, this particular number may include some 20 mm pst kiv 18-S at-rifles.

PICTURE: Antiaircraft-rifle L-39/44, antiaircraft-sight is visible in side of the weapon and so is the installation to a wood pole. (Photo taken in Ilmatorjuntamuseo). CLICK THUMBNAIL TO SEE LARGER PIC (90 KB).

"Military manual, 20 It.kiv./39-44 kalusto-ohje":

distance	hitting angle	penetration
300 m	60 degrees	20 mm
500 m	60 degrees	16 mm
300 m	90 degrees	25 mm
500 m	90 degrees	20 mm

Troops using L-39 as improvised anti-aircraft weapon gave the idea of designing a special antiaircraft-rifle capable to full-automatic fire (L-39 was semiautomatic and its low rate-of-fire severely decreased the changes of hitting aircraft). This new version would naturally also be equipped with antiaircraft-mount and sights designed specially for this kind use (two items that Finnish Army started equipping L-39 only as additional equipment during Continuation War). Prototype was made in January - February of 1944. The mount was simply system designed for installing the weapon in upper end of suitable pole (at least 8 inch in diameter). This weight of this mounting system was 9.4 kg.

PICTURE: AA-rifle L-39/44 (Photo taken in Ilmatorjuntamuseo). CLICK THUMBNAIL TO SEE LARGER PIC (43 KB).

Total production of L-39/44 numbered 325 weapons made (this number doesn't include 170 already manufactured L-39 antitank-rifles modified as L-39/44). As with L-39 antitank-rifle, to which L-39/44 anti-aircraft rifle was based, the sole manufacturer of this weapon was VKT (Valtion Kivääritehdas = State Rifle Factory). Structure of L-39/44 proved to be too fragile for large amount of full-automatic fire. L-39/44 was gas-action full-automatic firing from open bolt. The bolt stopped in its rear position only when the trigger was released. The sights used in the weapon were useful only for giving a summary aiming point. Once the firing started the shooter adjusted his aim according tracers. As mentioned this weapon had durability issues - the weapon's receiver proved too weak for stress of automatic fire. Year 1951 the number of remaining L-39/44 anti-aircraft rifles was 322. In mid 1950's Finnish military tried improving L-39/44. This development work resulted to two prototypes: 20 Itkiv/39-54L and 20 Itkiv/39-55/ST. In addition of increasing durability the development project wanted to increase rate of fire. Increasing the rate of fire succeeded - the prototypes reached about 500 shots/minute rate of fire. The reinforcements introduced to prototypes added weight of the weapon about 10 kg, but durability of the prototypes still proved very weak. Tests done at 1956 revealed that cracks started appearing to bolt recuperator after only 250 shots. When the prototypes were compared against new 20-mm antiaircraft-guns (which were also tested around that time) the shortcomings of antiaircraft-rifles became even more apparent. Decision was made in 1956: Developing of AA-rifles was stopped, existing L-39/44 were reserved for temporary training use and they were modified back to L-39 semiautomatic configuration.

PICTURE: AA-rifle L-39/44 readied for antitank use. The rifle still has attachment system for antiaircraft mount installed, so the bipod with skis has been attached in front of it. In front of the weapon is a magazine box contained loading magazine. (Photo taken in Jalkaväkimuseo). CLICK THUMBNAIL TO SEE LARGER PIC (59 KB).

SOURCES:

Markku Palokangas: Sotilaskäsiaseet Suomessa 1918 - 1988 osat 1 + 2.

Timo Hyytinen: Arma Fennica 2, sotilasaseet.

Guns vs Armour by D.M. Honner

Markku Palokangas and Maire Vaajakallio: Aimo Lahti, asesuunnittelun suuri suomalainen.

Erkki Käkelä: Marskin Panssarintuhoojat.

Mika Pitkänen and Timo Simpanen: Suomalaiset sotilaspatruunat 1918-1945 / The Finnish military cartridges 1918-1945.

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

Article: Suomessa käytetyt keveiden panssarintorjuntaaseiden patruunat by Esa Paananen in Ase-lehti magazine vol. 6/2003.

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

Military manual: Panssarintorjuntakiväärit by Päämaja. (1941)

Military manual: 20 mm:n panssarintorjuntakivääri L/39 by Päämajan Taisteluvälineosasto. (1942)

Military manual: 20 It.kiv./39-44 kalusto-ohje. (1947)

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

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