From http://www.quarry.nildram.co.uk/CannonMGs.htmORIGINAL: Chickenboy
ORIGINAL: JeffK
The US decision to keep to the 50cal was only acceptable in combat against japanese aircraft or German fighters.
Or German bombers. Or German transport aircraft. Or Italian fighters. Or Italian bombers. Or Italian transport aircraft. Or Chinese fighters. Or North Korean aircraft. Or Russian fighters. Or all manner of ground targets. Or all manner of naval targets.
I read the chart. Interesting, but the numbers suggest that one of the most successful aircraft of the war-the Bf109-was underarmed by comparison to many of the US 0.50-armed aircraft. Also, if it was all about muzzle velocity and throw weight, wouldn't the Bristol Beaufighter have been a superlative fighter instead of an also-ran?
The 20mm HS404 was a far superior weapon and 4 x 20mm much better than 6 x 50cal.
However it took a long time for the US to produce a combat worthy 20mm.
Having an excellent 20mm cannon system would have been nice. However, the 0.50 round was an excellent intermediate-sized round for many purposes.
I think the question could be asked as to why it took so many others such a long time to come up with a similar 0.50 / 12.7mm cartridge and MG that surpassed the Browning M2 0.50. Why on Earth were Axis (and other Allied) airplane armaments still using rifle-caliber cartridges late in the war? Maybe because they didn't have good options for a reliable intermediate-sized caliber weapon?
Also-have you read any autobiographies of pilots that used some of the cannon systems? They went "Winchester" very quickly due to limited ammunition-moreso than the smaller ballistics.
Anyways, I'm not convinced that a P-47D2 could be considered dangerously undergunned or only suitable for use against Japanese aircraft or German fighters. It was a very good multi-role aircraft and very well armed for its intended purpose.
A bit silly saying the Beaufighter should be the best because it had more guns isnt it. You have to get the guns pointing at the enemy and the Beau wasnt quite the most manouverable.
To return to the original question, were the Americans right to rely so heavily on the .50 M2 when all other combatant nations had a clear preference for cannon of at least 20 mm calibre? The answer has to be yes. It was adequate for its purpose, and was the only satisfactory aircraft gun in production in the USA. It was very reliable (except where the installations created problems), was made in huge quantities, and the simplification of supply by comparison with the diversity of weapons used by the Axis powers gave a major logistical advantage. However, the Americans could get away with using a weapon so deficient in destructive power not only because of the nature of their opposition, but also because the size and engine power of their fighters enabled them to carry a battery of at least six guns, thus making up in quantity what they lacked in destructive quality.
The advantages of the 20 mm Hispano M2 were not entirely ignored. It was carried by Lockheed P-38s, together with four .50 Brownings. It was also installed in nightfighters, which needed maximum firepower to convert a short firing opportunity into a kill. Four were installed in Northrop's P-61 Black Widow, and two could be mounted in a Grumman F6F-5N. The cannon's extra firepower was also appreciated for ground strafing.
After the war the US Navy quickly changed over to the 20 mm cannon in its improved, faster-firing and more reliable M3 form, but the USAF stayed with the .50 M3 until the fighting in Korea demonstrated once and for all that the HMG had had its day. From the mid-1950s the USAF at last replaced the old Browning with 20 mm cannon, initially the M39 revolver and then the M61 rotary - just as most of the rest of the world was moving up to 30 mm!
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