.50cals on early war British fighters?
During the late 1930s, the RAF determined that a large number of rifle-calibre machine guns was adequate for arming their fighters, specifically early variants of the Spitfire and Hurricane. However, it's common knowledge that combat experience during the Battle of Britain proved that this wasn't the case, and both planes were hastily armed with cannons as a result. While the Hispano would eventually become a reliable and effective weapon and would be the main British fighter gun for the rest of the war, it initially had trouble, especially when mounted in the Spitfire. I must wonder, would it have been more practical during the desperate days of the fall of 1940 to simply shoehorn American .50 M2s on to fighters as an interim fix? While it may have been tricky on the Spit, the thick wing of the Hurricane could have probably fit the standard six M2s without trouble, and it likely would have been more effective against tougher targets like He111s. In addition, the Royal Navy was starting to receive M2 armed F4F-3s (Martlets) at this time, and they were fairly easy to obtain via lend-lease. While late-war Spitfire variants would use them in tandem with Hispanos, they weren't widely used by the British other than on lend-lease aircraft.