The L-39 weighed 109 pounds
by MATTHEW MOSS
The mammoth Lahti L-39 anti-tank rifle, designed by Aimo Lahti — Finland’s greatest gun-designer — served Finland well during the 1940s. The 20-millimeter, semi-automatic anti-tank rifle’s barrel alone was 51.2 inches long, and the overall weapon weighed a staggering 109 pounds.
Through the 1930s, the Finnish military had debated the optimum caliber of weapon for use against armor. Officials suggested 12.7 millimeter, 13.2 millimeter and 20 millimeter — and planned to use the same caliber round in both anti-armor and anti-aircraft roles.
In 1935, the Finnish state weapons manufacturer Valtion Kivääritehdas, or VKT, prepared a prototype — the L-35/6, chambering the 13.2-millimeter round. The
Lahti himself preferred the 20-millimeter round, believing it had superior armor-penetrating capabilities. VKT produced two 20-millimeter L-39 prototypes in 1939 and the Finnish army deployed them alongside some of the 13.2-millimeter weapons during the Winter War against Soviet Russia.
One report on the effectiveness of the 13.2-millimeter L-35 guns claimed that they were “useless as antitank-weapons. They are usually malfunctioning and get easily frozen.” Combat experience proved that the L-39’s 20-millimeter ammunition was more effective than the 13.2-millimeter round was.
The Finns launched full production of Lahti’s L-39. The Finnish military changed the L-39’s caliber from 20-by-113 millimeters to 20-by-138 millimeters — the same caliber as the L-34 automatic cannon.
Weapons began entering service in late 1940 after the end of the Winter War. The L-39 saw its most extensive use during the Continuation War from 1941 to ’44. The Finns pressed the L-39 into a number of roles besides tank-killing. It served as an anti-aircraft gun. Some were mounted on patrol boats.
The colossal weight and 90-inch overall length of the L-39 made it difficult to transport, even when fitted with its bipod skis — which were replaced with spiked legs once in a firing position. The Finns mostly deployed the L-39 from fixed positions against the Soviets’ own defensive positions and vehicles.
VKT produced some 1,850 L-39 rifles between the end of the Winter War and the beginning of the Continuation War. Even with the introduction of new Soviet tanks with thicker armor, the L-39 still continued to be effective in the hands of a skilled gunner — to a point.
With their effectiveness as anti-tank weapons waning by 1944, the Finns modified around 240 of the rifles into strictly anti-aircraft weapons, converting them into open-bolt, fully automatic guns with a fixed firing pin.
The Finns also developed a 15-round magazine for use in the anti-aircraft role, replacing the previous 10-round magazine.
This ultimate L-39/44 proved to be too fragile for sustained fire. In 1956 the Finnish military converted the guns back to semi-automatic.
Originally published at www.historicalfirearms.info.