This is neat. This is a very awesome video of a 20mm antitank rifle firing at 16 steel plates to see the type of penetration it can do. As you can see by the slow-mo, it penetrated six of the plated with some pretty hefty holes. For 80-year-old ammo to do that much damage is pretty impressive.
image/text credit: FullMag
The Lahti L-39 is a Finnish 20 mm anti-tank rifle used during the Second World War. It had excellent accuracy, penetration and range, but its size made transportation difficult. It was nicknamed “Norsupyssy” (“Elephant Gun”), and as tanks developed armour too thick for the Lahti to penetrate its uses switched to long range sniping, tank harassment and with the L-39/44 fully automatic variant, employment as an improvised anti-aircraft weapon.
Aimo Lahti had doubts about the original idea of a 13 mm anti-tank machine gun and started working on a 20 mm design. Officers who wanted smaller calibre anti-tank weapons believed that the muzzle velocity of 20 mm shells was insufficient to penetrate armour and a weapon with a higher rate of fire and in a smaller calibre would prove useful.
As a result, Lahti designed two competing anti-tank weapons: a 13.2 mm machine gun and a 20 mm rifle. After test firing both weapons in 1939, they found that the 20 mm rifle displayed better penetration.The rifle is a semi-automatic, gas operated weapon with the piston located beneath the barrel and ammunition feed from detachable top-mounted magazine with bottom ejection for the spent cartridges.