Development of Finnish AT-rifles and antitank-machineguns started with argument. Some officers wanted 12,7 mm weapon, some wanted 13.2 mm weapon and some (including Lahti) wanted 20 mm weapon. Problem with accepting 20-mm weapon early on seems have been small muzzle velocity that existing 20-mm ammunition allowed at that time. It is questionable if any prototypes in 12,7 mm were actually made, but plenty of 13.2 mm ones were tested 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 neither calibre had ammunition available with tracer core.

As this would not have been enough Lahti got into argument with Colonel Raatikainen of Weapons Design Committee about mount of the new at-rifle. Raatikainen wanted mount to be similar as the one that Germans had, German mount had been planned to be suitable both to AA- and AT-shooting, but Lahti considered it to be unsuitable to AT-use. Another argument surfaced as Raatikainen and Saario wanted Swiss Oerlikon gun to be accepted (suspicions about Raatikainen and Saario representing Oerlikon and having own financial interests in this matter exist), Lahti was very much against this as Oerlikon gun had poor armour-penetration capability.

Artillery Generals Nenonen and Svanström joined the argument demanding 20 mm AA-rifle capable to penetrate 30 mm of armour. Live fire tests of summer 1939 finally proved that 20 mm was much more effective then 13.2 mm and decision about choosing 20 mm as calibre of AT-rifle was made. But before this lot of time had been lost and time was the commodity Finland was about to run out.

13-mm machinegun versions manufactured included:

• L-34: Could be used both in armoured vehicles and as AT-weapon, one prototype made.
• L-35/36: 2 weapons made for Landsverk armoured car.
• L-37: One prototype made with 15-round clips and another with 32-round magazines.
• L-38: One prototype made with 20-round magazine.
• L-39: One prototype with 30-round magazine and one with 30-round clips.

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.

(*) 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 used with experimental bullets. 13,2 mm x 120 B cartridge cases may have been made 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 AP-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 estimates, which buried 13.2 mm as possible antitank calibre for Finnish use for good (source: "Marskin panssarintuhoojat"):

• "(Soviet) Light (T-26) tank shot to all points even from distance of (only) 30 metres without any results".
• "13-mm machineguns are as useless in antitank-use. Usually they are malfunctioning and are easily frozen.".

These experiences made 20-mm calibre only surviving option for Finnish antitank rifle and resulted 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 antotank 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 manufacturer VKT (Valtion Kivääritehdas = State Rifle Factory) was more urgently needed for other weapons.

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 until being released with a switch located front part of the the weapons 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. The weapon used slightly arched 10-round magazine, which weight 3.4 kg fully loaded. Typical equipment included four magazine pouches each containing two magazines.

PICTURE: More detailed look to L-39 antitank rifle. (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 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 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 1944 when Finnish troops had 1,789 L-39, losses of L-39 were quite large in summer of 1944 as the weapon was too heavy for one man to carry it alone long distances. Losses could be replaced quite fast and when war ended Finnish troops still had some 1,650 weapons of this type, even in 1951 still 1,333 remained. Between 1960 - 1961 about 1.000 remaining L-39 were sold to United States, where they become very 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 1986. That was when the remaining 645 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, 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 use (two other things that L-39 was lacking). Prototype was made in January - February of 1944. The mount was simply system designed for installing the weapon in upper end of suitable stake. This installing system weight 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 (number doesn't include L-39 modified to 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. Unfortunately the weapon's receiver proved too weak for stress of automatic fire. Year 1951 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.