The following is excerpted from an article entitled, "1944 Fighter Conference", taken from Flight Journal magazine's special issue, "WW2 Fighters-The Inside Information on Aerial Legends", Winter 2000. The author is test pilot Corky Meyer, who personally attended the fighter conference in October of 1944. These "conferences" were an opportunity for test pilots to test fly a variety of current ally and captured axis planes, to determine vulnerabilities, and develop new designs, features, etc. The following information is excerpted from the 323-page report on all the subjects presented during the 35 hours of discussion at the conference.
"AIRCRAFT ORDNANCE
This subject was naturally of vital personal importance to all attendees. Cdr. Jack monroe, Chief of the Ordnance Branch of the Navy Bureau of Aeronautics, presented a detailed, candid and forthright rundown of the current situation.
I hadn't realized that as late as October 1944, the .50-caliber machine gun was still prone to jamming in firing bursts that exceeded five to 10 seconds. This problem was becoming more serious as Army Air Corps and Navy fighters were turning from defensive air-to-air to offensive air-to-ground strafing. He discussed two methods of increasing the firing rate but stated emphatically that there was no imminent solution to its inadequate reliability. He also predicted that further increases in rate of fire would only compound the problem.
20MM CANNON VERSUS .50-CALIBER GUNS
In Monroe's discussions, it became apparent that the British and the U.S. Navy were in the process of making a switch from .50-caliber guns to 20mm cannon. The principal reason was that although the 20mm cannon had a slower rate of fire, it put out more weight of metal than the .50-caliber gun in a given time, and it did not jam during a 20-second, full-load burst. The U.S. Army was the principal aircraft-gun developer here. The Army Air Corps personnel who attended the conference adamantly held to the position that to get more lethal density from that configuration, .50-caliber guns must remain the wing-mounted armament. The 20mm would be tolerated only for the centerline gun installations such as those in the P-38 Lightning and F7F tigercat. As the discussions progressed, we were to see many more adamant, opinionated service decisions."
Seems there were many, varying opinions, but at least with the .50, gun jams were a definite reality, and modeling to match this would definitely help decrease some of the spray and pray, at least in planes carrying the .50.