On Oerlikon gun designations


I have a copy of Oerlikon booklet no. 2345, about 20 mm ammunition for the 5TG, 204GK and 251/20 guns. This booklet is undated but must be from the early 1960s.

I know the 5TG gun and percussion-primed ammo well because it was used by the Spanish army. The 204GK gun is a revolver gun and the cartridges are electrically primed. But I don’t know nothing about the 251/20 gun.

At what time the Oerlikon designations were changed, from i. e. 5TG to KAB? I guess the K stands for Kanone, the second letter designates the caliber (20, 25, 30 or 35 mm) and the last letter means the gun model.

What was the KAA Oerlikon gun? Perhaps the “S” type"?

Is there a list of the Oerlikon gun designations available anywhere?

Also, I have seen references of a 20/85 Oerlikon naval gun* which uses 20 x 128 ammo. This means a 85-caliber barrel length. The 5TG gun is a 20/120, meaning a 120-caliber tube. Doesn’t the short 85-caliber length negate the superiority of the 20 x 128 cartridge?

  • And pictures of Santa Bárbara ammo for it. Some lots have been made for the Spanish navy, mainly HEI, HEI-T and TP.