[Fraxinus]

Failure to equip a new aircraft with an appropriate weapon system has always been a uniquely American blind-spot.

While I think the author has a point I think he protests too much with this line. It is good to have weapons development and air frame development to be done by completely separate teams, and for a new weapon to be dependent and a new air frame. At the same time the British waited untill well into WWII to up gun their planes from .30 to .50 machineguns. The US was arming all new aircraft with Ma Deuce from ~1936 untill well after it was shown to be inadequate ~1950. The Brits were using 20MM machine guns in some Spitfires before the end of WWII

[pfflier]

The British Germans and Japanese all used armament involving rifle caliber (~.30 cal) ammunition. The Germans and Japanese supplemented that with 20mm cannon but in relatively small numbers (one or two per plane) using them for close range shots. As you said, the British up gunned to the 20mm late in the war.

Without a doubt, the Germans were best at using their cannon caliber weapons to devastate 8th AF bombers and the Russians through 1943 and into 1944.

The .50 cal had better ballistics and higher rates of fire than the 20mm used in WWII. For the US it also meant all airplanes used the same ammunition, easier to deal with logistically.

Even post WWII the 20mm was a marginal performer because of operational problems causing jamming at altitude and under G loads. The first really effective US 20mm was the M-61 (Vulcan) multi barreled cannon fielded on the F-104 to present. The navy used single barrel cannon through the F-8 and only used the M-61 starting with the F-14.