View Full Version : Question about MGFF, Hispano and MG151

07-17-2005, 06:34 AM
I read somewhere that the Hispano was almost a direct copy of the MGFF, a gun which was phased out by the LW, known as unreliable and slow firing.

They replaced it with the MG151, which I am presuming was more reliable and a better all round gun...

So why did the allies use a copy of an older 20mm design throughout the war??

Is the statement that the Hispano is a copy of the MGFF just plain wrong?

07-17-2005, 07:25 AM
For French fighters such as the Dewoitine D.501 and Morane-Saulnier MS.405, Hispano-Suiza had manufactured a licence-built version of the Oerlikon cannon, as the HS.7 and HS.9. Engine designer Mark Birkigt decided to develop a new 20 mm cannon, the HS.404, with a higher performance. The HS.404 had a different action, a higher rate of fire, and a much higher muzzle velocity. The British were impressed, and by 1939 the Hispano was in production in Britain. Originally it was fed from a 60-round drum, but in the autumn of 1941 a satisfactory belt-feed mechanism was produced. The Hispano was slim, but long (2.36 m long, compared to 1.76 m for the ShVAK) and heavy. Rate of fire of the Mk.II version was lower than that of other 20 mm cannon, but the muzzle velocity was high. Initially, solid AP ammunition was preferred, but later in the war a mixture of HE/I and SAP/I was introduced. The Mk.V was a lighter and faster-firing version, without in-flight cocking mechanism and with a shorter barrel.


You might want to look at that link as it has all sorts of information on guns, combination of weapons, hitting power, etc.

It seems most of the 20mm cannons of the war were somehow inspired by the Oerlikon design but thats where they diverge. The Hispano was essentially a French design with a very high muzzle velocity, long barrel, and large shell.

The early Hispano had a series of problems that were separately solved by the USN and the RAF (as both of these services started using 20mm cannons). Dust, being prone to jamming, and all sorts of nasty things were worked out. The British called the upgraded (and continually tweaked) version the Mark II and later followed by the Mark V. The USN called it the M2 20mm cannon which you can see on the F4U-1C Corsair and with the USAAF (also known as M2) in the P-38 and P-400.

07-17-2005, 07:47 AM
The MG-FF used an advanced-primer-ignition blowback mechanism; the Hispano a gas-unlocked blowback mechanism incorporating a pivoting locking piece; and the MG151/20 a rotating-bolt short-recoil set-up. Other than their nominal calibres, these guns are essentially unrelated.

07-17-2005, 07:56 PM
Thanks Ice and HS http://forums.ubi.com/groupee_common/emoticons/icon_smile.gif

PS - Icefire, Great playing with ya on UKD 1 !