Finland's "Elephant Gun"

Many nations searched for effective anti-tank weapons in the interbellum years. One of the most popular countermeasures was the anti-tank rifle. These rifles ranging in caliber from 7.92 to 20 mm were issued to infantry units. Finland also followed this path as it nervously observed the development of armoured vehicles by its eastern neighbour, the Soviet Union.

Initially the Finns chose the 13.2 mm caliber, but doubts about its effectiveness crept in during development. The army decided to play it safe and develop a 20 mm anti-tank rifle, then make the final decision after comparative trials. In early 1939 the task of developing a 20 mm anti-tank rifle was given to the most famous Finnish arms designer, Aimo Johannes Lahti. By that time he had already designed the L-35 pistol and quite successful 20 mm aircraft autocannon. Lahti used his experience with the latter in designing a new anti-tank rifle.

Design

The anti-tank rifle used the 20x138B Solothurn cartridge used not only in anti-tank rifles made by that company, but in German Flak 30 and Flak 38 AA guns as well as the Italian Breda M/35.

The L-39 heavy anti-tank rifle was a semiautomatic gas operated rifle. The barrel was tapped for gas about two thirds of the way out, right behind the perforated barrel shroud. The gas tube is located under the barrel. It's equipped with a four-position valve to allow the mechanism to function in various atmospheric conditions and levels of barrel fouling. The barrel is equipped with a box type muzzle brake with five openings on each side. A tin casing is installed over the muzzle brake during travel. A perforated wooden shroud is installed over the barrel to make it easier to transport.

The receiver is rectangular in shape. A stock with a rubber pad is located on the rear. A wooden cheek rest is screwed in from the left. A pistol grip with a trigger is located underneath. The bolt handle is located on the right side of the receiver and the safety lever is on the left.

The anti-tank rifle is equipped with a folding bipod attached to the front of the receiver. There is also a mount with two wide and short skis. Iron sights are adjustable from 100 to 1400 meters. They are located to the left of the barrel axis, as a removable double-stack magazine fitting 10 rounds of ammunition is located in the center.

The ski mount is a distinctive feature of the Finnish anti-tank rifle.

The anti-tank rifle was crewed by two men. In winter the rifle was transporter either on a sled or on two long skis with slots for two ammunition boxes.

Trials

Comparative trials of the 13.2 mm and 20 mm anti-tank rifles took place in the summer of 1939. The resulted were mixed. The 20 mm gun was much heavier, but the penetration was not considerably greater than that of its lighter competitor. The fact that it had a much more noticeable beyond armour effect was more important. Its shell gave twice as many fragments after penetration, which gave a higher chance of disabling the tank's equipment or crew. As a result, the decision to stop working on the 13.2 mm anti-tank rifle and continue work on the 20 mm rifle was made on August 11th.

General Axel Erik Heinrichs, the man in charge of Finnish armament, signed an order to immediately accept this weapon into service as the 20 panssarintorjuntakkivääri L-39 (or 20 pst.kiv. L-39 for short) on September 6th, 1939, soon after the start of WWII. Production was set up at the Valtion Kivääritehdas factory in Jyväskylä. Here it gained yet another name: VKT-L (acronym of the factory name and the name of its creator).

L-39 anti-tank rifle in firing position.

Service and combat history

Not a single anti-tank rifle was built before the Winter War. Deliveries began only after the fighting started. The need for anti-tank weapons was so great that Finland had to turn abroad. 200 British 13.97 mm Boys rifles were purchased, but only half of the order arrived before the ceasefire. The Finns didn't like the Boys very much. Many of them were given to the Swedish Volunteer Brigade. Additionally, 85 8 mm anti-tank rifles arrived from Hungary. It is unclear where they came from, as Hungary did not produce this type of anti-tank rifle or use it in their armed forces. It's likely that these were Polish rifles that ended up in Hungary in September of 1939 along with interned Polish soldiers. Finland also attempted to purchase the heavy Solothurn S-18/1000 in Switzerland.

Let us return to the L-39. The dramatic situation during the first days of the Winter War forced the mobilization of both prototypes of this gun. They were both sent to the anti-tank platoon of the 28th Rifle Regiment, a part of the Metsäpirtti group, which was in turn a part of "Group R" (Rautu). This regiment fought a delaying action in Karelia near Lake Ladoga before retreating towards the main line of defense. Anti-tank rifles showed their effectiveness, penetrating the relatively thin-skinned Soviet tanks at ranges of up to 400 meters.

The amount of Lahti anti-tank rifles on the front lines gradually increased, but never reached authorized levels. 277 L-39 anti-tank rifles (this figure possibly included the aforementioned Solothurn) were available on March 13th, 1940.

L-39 anti-tank rifle crew in fighting near Viipuri (Vyborg). August 1941.

The L-39 (nicknamed "Norsupyssy" - "elephant gun") was widely used during the Continuation War, but it only performed its intended function during the early stages. It turned out that the Lahti was powerless against T-34 and KV-1 tanks. The L-39 had other uses. The long effective range and impressive fragmentation of the shell made them useful for suppression of machine gun nests, field fortifications, and other such targets. The weapon was also effective at counter-sniper fire and somewhat of a predecessor of modern high caliber anti-materiel rifles.

L-39 anti-tank rifle on an improved anti-aircraft mount. Ontojoki river, June 1944.

Modifications

The decreasing effectiveness of the L-39 as an anti-tank weapon and shortages of light anti-aircraft weapons in the Finnish army resulted in the transformation of the L-39 into an ersatz AA gun in early 1944. The gun received a new spring and trigger mechanism, allowing it to fire in bursts at a rate of 80-100 RPM. The rifle was somewhat lightened from 49.5 to 48 kg and an AA gun sight and AA mount weighing 9 kg were added to the set. This was less of a real gun mount and more of an adapter for attaching the rifle to the top of a log embedded into the ground. A new 15 round magazine was developed to increase the practical rate of fire. The new variant was named 20 pst.kiv. L-39/44. These rifles were used towards the end of combat against the USSR, including for fighting the Il-2 Sturmovik.

L-39/44 light AA rifle, vicinity of Kouvola, October 1944.

Finland made an attempt at modernizing the L-39/44 in the mid-1950s, altering the gas system to increase the rate of fire. The experimental 20 ltkiv/39–54L and 20 ltkiv/39–55/ST went through trials in 1956, but unsuccessfully. On one hand, the theoretical rate of fire indeed increased to 500 RPM, on the other hand the increased pressure limited the rifle's lifespan to about 250 shots. The ersatz AA guns also weighed 10 kg more than the initial gun. This was the end of development of 20 mm light AA guns in Finland.

The 20 pst.kiv. L-39/44 was not the first Finnish AA gun based on the L-39. Aimo Lahti developed an autocannon with a theoretical rate of fire of 700 RPM and a practical rate of fire of 250 RPM back in 1940. These guns were installed in pairs on a mount similar to the German Flak 30 and Flak 38. The weapon was accepted into service as the 20 ltk/40 VKT (also known as L-40 Vekontin). Finland used these weapons for training until the 1970s and maintained them as a part of a mobilization reserve into the 1980s.

The L-39 was only used to arm armoured vehicles once. One was installed into a Landsverk L-182 armoured car instead of a 13.2 mm L-35/36 machine gun.

2076 L-39 and L-39/44 anti-tank rifles were built in total. The first contract for 410 L-39 rifles was finished by June of 1941. 496 more were ordered in March and delivered by December. A new order for 1000 rifles was given in November of 1941. 946 of those were delivered by May of 1944. The last 54 of the batch were delivered as L-39/44 variants. Finally, another order for 170 rifles was made in July of 1944, all in the AA configuration. The Finnish army ended up with about 100 more L-39/44 rifles than produced new. An order was given in November of 1944 to convert 606 L-39 rifles into the AA variant, but only a small portion of the order had been completed by the time it was cancelled. These rifles remained in use until the 1960s, after which about 1000 rifles and 200,000 rounds of ammunition were sold to collectors, chiefly in the United States.

The Lahti L-39 (similar to other 20 mm anti-tank rifles, including the Swiss Solothurn and Japanese Type 97) was the result of wanting a "hand cannon" with high ballistics. The result was not as impressive as intended, as the 20 mm shell was no longer sufficient by 1940 to combat armoured vehicles and the rifle was way too heavy. It weighed 2.5-3 times as much as analogous weapons (the British Boys and Soviet PTRD/PTRS). However, since Finland had a shortage of anti-tank artillery, the L-39 was in demand throughout the entire war. The rifle's high precision allowed it to be used against small targets like vision slits and gun ports. It is also important to remember the conditions in which fighting took place on the Soviet-Finnish front. The 20 mm anti-tank rifle could be used effectively in the forests, but would not have been as effective in the open, where the gunner's position would be spotted long before his enemies entered effective range.

Tactical-technical data of the 20 mm 20 pst.kiv. L-39 anti-tank rifle.

Caliber	20 mm
Mass (with bipod, no magazine)	49.5 kg
Mass of a loaded magazine	3.4 kg
Combat mass (with magazine, bipod, and skis)	57.7 kg
Shell mass
Armour piercing	148 g
AP-tracer	152 g
Cartridge mass	337 g
Barrel length	1300 mm
Muzzle velocity	800 m/s
Rate of fire
Theoretical	30
Practical	15
Maximum range	1400 m
Penetration at 30 degrees from normal (theoretical/practical based on 1943 trials)
300 m	20/20
500 m	16/15
1000 m	12/9

Original article by Andrey Haruk.