P-39's Firepower, a fighter or an attacker?

according to the video Introduction of P-39 from youtube, the gun mounted on wing side was 20mm or I heard wrong? However the image presented in video truly is close to .5 caliber rather than 20mm cannon.

The video in question [link here] clearly states one 20mm or 37mm along the fuselage centreline, plus two ‘synchronized 50 caliber guns’ [i.e. 0.5in] above the nose and ‘two 30 caliber in each wing’ – at 4 min 15 sec. That matches the standard P-39 armament as published extensively in numerous different sources.

(PS – just a minor correction to nuuumannn’s post, I’d expect US Airacobras would’ve had 0.3in, RAF, and Commonwealth used examples 0.303in.)

Regards,

according to the video Introduction of P-39 from youtube, the gun mounted on wing side was 20mm or I heard wrong? However the image presented in video truly is close to .5 caliber rather than 20mm cannon.

According to accepted info, the P-39’s standard armament was 1 x 37 mm cannon, 2x nose mounted .50s and four .303s, or six .303s. In the RAF versions the 37 mm was replaced with a 20 mm. the P-39Q had 2 x .50s in under wing pods.

The Soviets used the P-39 as a ground attack aircraft against soft targets, but the Americans didn’t supply armour (or ‘armor’) piercing rounds, so they were not usually used as tank busters. As we all know, the Russkies loved the Airacobra; most of the top scoring Soviet aces got many of their victories in them.

Tank busting Hurricanes carried 2x40mm guns in the western desert.

Many aircraft carried 60lb rockets, Typhoon had a set of eight plus their 4x20mm cannon. It was said it was equivalent of a broadside from a Destroyer.

The Airacobra did not have 4x20mm cannon.

Can you be more precise just what you do mean, for I’d have thought that the 4x20mm cannon of the Hurricane outweighed the P-39’s slow-firing cannon.