[Radoye]

from http://www.quarry.nildram.co.uk/37-40mm.htm

The RAF's 40mm Anti-Tank Gun

The importance of being able to destroy tanks from the air became obvious. Bombs were not sufficiently accurate, so thoughts turned to large-calibre guns. The naval 2 PR No.1 cartridge had already been selected as the basis for an airborne bomber defence gun which had actually been fitted to a much-modified Wellington bomber. The RAF therefore decided to adapt the gun for anti-tank purposes. The reason that the naval cartridge was chosen rather than the army's 2 PR No.2 was that the lower power reduced recoil and led to a smaller and much lighter gun. The lower velocity was considered acceptable as the aircraft would be firing at very short range. Special loadings were developed for the case, the standard AP shot weighing 1.13 kg and capable of defeating armour plate about 50mm thick at 360m (although the normal attack range was considerably less than this). A 1.36 kg shot was introduced in 1942, improving penetration by 9%.

Vickers S:


Naval 2pdr "pom-pom":


Army 2pdr ATG: