Historic Spitfire Mk1/1a loadout

[winny]

Originally Posted by Tavingon

Why only have a couple of guns with armor peircing ammo, was it too expensive?

Partly to do with supply, but it was basically deemed too ineffective. AP is only effective if it hits 'straight on'. They found that the bullets would tumble as they passed through the superstructure drastically losing speed and just bounce off any armour plate (this applies mainy to bombers). Ball ammo didn't suffer from this effect (tumble) and was mainly there because it was in plentiful supply and it was pretty good at killing the crew.

Interestingly, the Germans realised this way before the Brits and they phased AP out except for specialised roles - ie. Ground attack. They knew the best way to bring down an aircraft was to use HE rounds, hence the early adoption of cannons.

EDIT: Another point about the RAF guns during the BoB was that they tended to load all the guns with the same type of ammo, they didn't mix it. This was because they found that the different recoil characteristics of the rounds meant the guns were more likley to jam if mixed ammo was used. There were exceptions of course, but this was the standard for RAF armourers. If you watch any RAF BoB gun camera footage you can notice this.