20mm for P-28: any issues?

[tomo pauk]

Fellas, I'd like to know how good/bad/reliable was the 20mm cannon of P-38s. Thanks in advance

 

[Jabberwocky]

Fellas, I'd like to know how good/bad/reliable was the 20mm cannon of P-38s. Thanks in advance

In comparison with other US 20mm mountings, the 20mm in the P-38 was quite reliable. The nose position was a rigid mounting that was kept properly heated, which suited the cannon well.

In comparison with the .50 Browning, the US versions of the Hispano were not very reliable at all

In the P-38, the 20 mm averaged 1 stoppage every 505 rounds. This is in combat.

This is compared to 1 stoppage for every 3920 rounds for the .50s in the P-38. This is an outstanding reliability record though.

In the P-51B/C, the Brownings averaged 1 stoppage every 954 rounds. In the improved mounting in the P-51D, this increased to an average of 1 stoppage every 1447 rounds.

In the P-47, the Brownings averaged 1 stoppage every 1802 rounds.

All stoppage rates improved as the war progressed – incrementally for the .50 and notably for the Hispano around April 1944 and again in July 1944

On average, the US 20 mm in the P-38 was between ½ and 1/8th as reliable as the US .50 cal, depending on the mounting

In RAF ground testing, early UK made Hispanos averaged about 1 stoppage every 268 rounds. At the same time though, US made Hispanos averaged about 1 stoppage every 43 rounds.

I don't have any comparable RAF reliability figures for 20 mm use.

The RAF did have problems with US manufactured 20 mm ammo as well. There are RAF reports from Malta that US ammo tended to jam more than US ammo, due to misfires