Why was the Gast gun never used in aircraft during WWII?

ShVAK said:

Nothing inherent in the Gast design itself, but what about longer barrels? The Mk 108 was deficient in muzzle velocity because its high ROF mandated a short barrel to prevent misfires. Since a Gast is basically two guns just linked together, wouldn't two guns at 400 RPM each be able to obtain a higher rate of fire than one Mk 108?

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It wasn't misfires they were trying to stop, it was the cartridge case rupturing and letting high pressure gas back into the action of the gun. The short barrel allowed the shell to clear the muzzle sooner and drop the internal pressure as the bolt and case moved to the rear. A longer barrel would still have had the shell inside as the rear cartridge came out of the chamber and the higher pressure could have blown out the side of the case. Yes you could use a stronger spring, heavier breechblock(bolt) to slow down the bolt movement (rate of fire) to get better velocity.
But again, the Gast is almost two complete guns, A Gast firing 30 X 82RB ammunition is going to weigh almost double what a single MK 108 did ( if built of the same materials and to the same standards)

ShVAK said:

What if there was a way to unlock the link in the instance of a malfunction allowing each gun to operate independently

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For that to happen you need a main spring to drive the bolt forward. I don't believe the Gast used mainsprings. You also just cut the weight/mass of the bolt assembly in half meaning the bolt will accelerate much more quickly leading to early opening and the case ruptures mentioned above.

Gas operated and recoil (moving barrel guns) used the gas/recoil system to operate a lock that delayed the opening of the bolt. Because they were not depending on the weight of the bolt and the strength of the main spring for this delay their bolts could be lighter and move faster once they had unlocked.

An accurate two second burst from a Spitfire or Hurricane could deliver about 250 rounds on target.

There are always instances of heavily damaged aircraft returning home,just as one lucky shot could bring one down.

The RAF had considered other armament at the same time as the eight .303 option. The then new 20mm Hispano-Suiza cannon was considered "supersensitive" to rigidity of mounting and difficult to mount in aeroplane wings. The RAF would only consider the cannon if 60 rounds per gun,in drums,could be fitted.

In 1938 Dowding wrote to Sholto-Douglas,clearly unimpressed with the cannon.

"There has been a lot of talk about the efficiency of the 20mm cannon and I have seen no proof that this gun will give decisive results.We ought to have carried out the most careful experiments to prove its value before we adopt it.If this was not done I shall wake up in a year's time and be told I am committed to having 15 squadrons of something with a 20mm cannon whereas I can tell you now I do not want any and so perhaps save a large sum of money."

It was not until early 1940 that Dowding was convinced by the 20mm cannon. No.19 Squadron was informed on 1st July 1940 that it was to be equipped with cannon armed Spitfires. They were a disaster,the cannon jamming for a variety of reasons. On 15th July Dowding wrote undiplomatically to the Air Ministry "Two cannon Spitfire unreliable."

The stop gap solution was the 2 cannon and 4 MG armed Spitfire.

There were other problems too,maybe for another thread. As an example the first Spitfire IB to see action with 19 Squadron in October 1940 had to be flown at full power just to keep up with its machine gun armed counterparts.

It's another example of things not being as simple as they appear. "Just" mounting cannon in the wings of the Spitfire eventually led to a modification of the wing spar.

Fighters armed with eight .303 machine guns shot down hundreds of aircraft in the summer of 1940 and that armament cannot therefore be described as "inneffective"

Cheers

Steve

Resurrecting an old thread here but the Gast Gun was used in WW2 aircraft. It was redesigned to fire .63 caliber cartridges. The ammo was loaded at Twin Cities Arsenal. They used a necked up 50 BMG cartridge case. The gun and ammo were designed for naval strafing and were supposed to penetrate the decks of enemy ships.
The only application I could find was that they were put into B17s but only in the one South Pacific Squadron. The gun pod was fitted to the right side just aft of the cockpit. Images of the B17s from that squadron show only a blank cupola on the right side. The pictures may have been taken right before or right after the removal of the Gast Guns.
The only combat usage I could find was in the battle of the Coral Sea. As most of you know this battle was a mess. The Japanese fleet fired on one of its own ships when the convoy was steaming in a half circle. American aircraft then strafed their own American ships causing some casualties.
The guns were removed and scrapped after one battle. The only official reason was that there were no personnel trained to maintain the system. All examples were scrapped. I hope that someone here has a sample cartridge. It will near the twin cities code on the base with a stab crimp primer pocket exactly like the base of the 50 BMG.