Some problem about the hispano cannon

[noob2331]

The hispano MK2 cannon used by Britain during World War II was developed from the French hispano-suiza 404 cannon. I noticed that compared with the original version of France, the fire rate of the MK2 used by the British was slower. I want to know what improvements did the British make to the French design?

 

[Greyman]

The main changes were:

• ribs were added to the top and bottom of the body to enable the gun to be mounted in a cradle for turret use and to provide datum faces for production
• the attachment of the back block to the body was re-designed and strengthened so that the breech block would not be blown out of the gun if the gun fired with the breech unlocked
• the extractor was redesigned to improve the control of the case and increase the life of the extractor spring
• as the redesigned extractor was increased in stiffness, a buffered ejector was required and this involved redesign of the ejector, magazine catch and the magazine carrier
• the unlocking plates were redesigned to incorporate an inertia block for reducing 'bounce'
• consequent on the new extractor and unlocking plates, considerable modifications were made to the breech block
• the piston of the cocking cylinder was redesigned to facilitate production
• a new return spring assembly was designed incorporating the triple wire spring
• the sear assembly was redesigned to improve its performance

It was found during testing that reliability and life of the gun was greatly improved if the rate of fire was dropped about 100 rnds/min -- so this was done.

The French agreed with most of these changes and were going to incorporate them into their guns in order to standardize.

 

[noob2331]

Thank you for your answer! appreciate!

 

[elbmc1969]

The hispano MK2 cannon used by Britain during World War II was developed from the French hispano-suiza 404 cannon. I noticed that compared with the original version of France, the fire rate of the MK2 used by the British was slower. I want to know what improvements did the British make to the French design?

The 404 suffered from wildly inconsistent firing rates in production models. They almost all fell short of the specifications. The British improved consistency of firing rates throughout the development of the weapon.

The cause of the variation in rate of fire of the 404 is not clear. It could be workmanship, materials (spring quality), or design flaws (such as loose tolerances).