Experimental PTR RES anti tank gun from 1942. 20 mm bullet was based on 45 mm casing, that gave it velocity of around 1300 m/s with roughly 60 mm of penetration at
Kurchevsky recoilless anti-tank rifle (USSR) - Modern Firearms
Best Gorenko Anti-Tank Rifle loadout in Warzone Pacific | Rock Paper Shotgun
world war two - What damage did anti-tank rifles hope to inflict on tanks in WW2? - History Stack Exchange
The Anti-Tank Rifles of World War II | SOFREP
Anti-tank rifles - just how do you do anything with them? : r/redorchestra