USAAF 0.60-caliber Machine Gun????

A36Apache

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Quick question: Wasn't there a P-38 that was trialled (or at least mocked-up) with 0.60cal guns?
Hi,
there was a prototype tested with three .60 inch guns, the barrels extended quite a way foward of the nose. It did not work very well, I think they had problems with the feed systems.
Really? I would've thought Chinn would have mentioned that considered he mentioned the tests of the design on the XP-83.
 

iverson

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The P-38 tests were done in 1947, according to the Schiffer book (whose title I don't recall just now). There were multiple gun failures.

All of the 0.60-cal guns had reliability problems, and none were ever fully developed. I've always wondered what possessed the USAAC and Ordnance Department to pursue a line of development that everyone else abandoned in favor of 20-mm shell-firing cannon. This seems especially odd since the 0.60-cal guns were developed from the 20-mm Hispano and MG151/20, the latter a more effective, 20-mm conversion of a 15-mm (~0.60-in) machine gun.
 

Tony Williams

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In a way, two of the .60 cal guns were fully developed: what became the M39 revolver cannon and the M61 rotary were initially developed in .60 cal, but then modified before adoption by necking out the cartridge to 20mm - just as Germany did with the MG 151/20. The resulting 20 x 102 round is still very much in service.
 

Colonial-Marine

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Isn't the smaller of two popular post-war Soviet 23mm calibers itself a necked up version of the 14.5mm cartridge used in the KPV (and earlier WWII AT rifles)? Seems like a pretty common practice.
 

Tony Williams

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Isn't the smaller of two popular post-war Soviet 23mm calibers itself a necked up version of the 14.5mm cartridge used in the KPV (and earlier WWII AT rifles)? Seems like a pretty common practice.
Yes, the 23x115mm is just a necked up 14.5mm.
It may be worth pointing out that while most necked-up cartridges retain the same overall length (thereby requiring only a barrel swap to change the ammo) the 23 x 115 has a long projectile which means that the guns for it need a longer action and body compared with the 14.5mm. The Russians have been toying with a suitably lengthened KPV to take the longer 23mm ammo, known (last I heard) as the KPVB.
 

HoHun

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Hi iverson,

The P-38 tests were done in 1947, according to the Schiffer book (whose title I don't recall just now). There were multiple gun failures.

Additionally, in "Fighter Pilot's Heaven" by Donald S. Lopez, tests of the 0.60" machine gun in a P-38 during WW2 is mentioned (p. 15f). Lopez did the functional firing tests under steady accelerations up to 6 G, during which the gun worked reliably, but he noticed considerably barrel vibration during firing. It turned out that the original design of the gun mounts was not suitable for the guns, and as far as Lopez states that basically killed the hopes of getting the 0.60" gun into service during the war.

Lopez also did night firing trials, and found that the muzzle flame was massive, blinding him seriously (though he was advised to keep one eye closed when pulling the trigger, which turned out to be quite vital), and he reports circling for 15 minutes after firing off the ammunition while waiting for his night vision to return so he could return to base and land.

Regards,

Henning (HoHun)
 

Tony Williams

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Hi iverson,

The P-38 tests were done in 1947, according to the Schiffer book (whose title I don't recall just now). There were multiple gun failures.

Additionally, in "Fighter Pilot's Heaven" by Donald S. Lopez, tests of the 0.60" machine gun in a P-38 during WW2 is mentioned (p. 15f). Lopez did the functional firing tests under steady accelerations up to 6 G, during which the gun worked reliably, but he noticed considerably barrel vibration during firing. It turned out that the original design of the gun mounts was not suitable for the guns, and as far as Lopez states that basically killed the hopes of getting the 0.60" gun into service during the war.

Lopez also did night firing trials, and found that the muzzle flame was massive, blinding him seriously (though he was advised to keep one eye closed when pulling the trigger, which turned out to be quite vital), and he reports circling for 15 minutes after firing off the ammunition while waiting for his night vision to return so he could return to base and land.

Regards,

Henning (HoHun)
Hi Henning,

Do these reports say anything about which .60 cal MG was involved? Modified versions of both the MG 151 and the Hispano were made for this ammo in the US.

The size of the muzzle flash is connected to the barrel length. If the barrel is too short for the cartridge, then you will get a large muzzle flash as the propellant continues burning after leaving the muzzle.
 

HoHun

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Hi Tony,

Do these reports say anything about which .60 cal MG was involved? Modified versions of both the MG 151 and the Hispano were made for this ammo in the US.

The size of the muzzle flash is connected to the barrel length. If the barrel is too short for the cartridge, then you will get a large muzzle flash as the propellant continues burning after leaving the muzzle.

Unfortunately, he doesn't state the gun type. He mentions that he was quite impressed by the barrel length though, as the barrels stuck out 3 feet from the nose of the P-38 (two 0.60" guns were installed), though.

I thought he stated that the rest of the nose was used to install camera and other recording equipment, but re-reading the pages, it looks like I confused that with comments he made later in the book about testing the Davies Draper sight.

The project officer in charge of the tests was Colonel Moon of Wright field, just in case it helps you to place the weapon from the context.

Regards,

Henning (HoHun)
 

A36Apache

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Quick question: Wasn't there a P-38 that was trialled (or at least mocked-up) with 0.60cal guns?
Hi,
there was a prototype tested with three .60 inch guns, the barrels extended quite a way foward of the nose. It did not work very well, I think they had problems with the feed systems.
I'm not sure if this helps, but the P-38 in this picture appears to be BUNO 44-23801, not sure if the book the image it is from states that but this seems to be the best match I could find...
 
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