British 6pdr/57mm automatic AA guns

[JFC Fuller]

Thanks Chris!

Based on just some very rough eyeballing and your figures (if I have understood them correctly) that turret is very approximately 3.9m from the deck to the top of the gunners cabin, 4m from turret front to turret rear (6.4m from the muzzle to the turret rear) and 4.5m between the turret sides.

Can you clarify which measurement is 14ft 2in (4.32m)?

 

[CJGibson]

Oops! It's 7ft 9in from deck to trunion centres, 14ft 2 in from deck to cupola top and 14ft 6in from muzzle to turret centre of rotation.

Previous post modified.

Chris

 

[Abraham Gubler]

I've looked at the original drawings and I have a spot of good news on the scale front.

They are very interesting dimensions Chris because it indicates that the weapon inside the mounting is quite different to the Bofors 57mm. I had assumed a scale based on the gun being about the same size as the Bofors gun but with these dimensions it is about 20% bigger. The barrel for starters is a 70 calibre bore whereas the original Bofors 57mm only had a 60 calibre bore, moving to 70 calibres in the late 1960s. It also indicates that the bottle cartridge is 58cm overall length, 11cm maximum diameter and 40cm cartridge length.

What this means is if this Vickers 57mm was loaded with the same sized 57mm HE projectile (5.4 calibre projectile) as the Bofors guns the cartridge would have twice the internal volume for propellant as the Bofors 57x438mm rimmed cartridge. This is quite a substantial increase in potential propellant and therefore muzzle velocity. The Bofors 57mm firing through the same length barrel as the Vickers gun had a muzzle velocity of 1,025 mps (3,360 fps). If this gun was loaded with propellant to fill that large bottle cartridge it would likely had a muzzle velocity of 1,200 mps or more which is quite an improvement compared to the Bofors 57mm/60 gun that only fired at 880-890 mps (2,887-2,920 fps).

So this gun and mounting is more than just a British competitor to the Bofors 57mm it is something in a different league. Firing at a far higher velocity and even doing so with potentially much larger rounds if they were going to use some of the technology looked at for the British 5” MCDP weapon. Which included studies of shells of up to 8 calibres in length and corresponding high sectional densities for retaining velocity in flight and larger shell weight for enhanced lethality.

 

[CJGibson]

If only I could please others with a couple of inches...

Chris

 

[Abraham Gubler]

If only I could please others with a couple of inches...

Its not the size of the DACR that counts but how you use it.

 

[Tony Williams]

It also indicates that the bottle cartridge is 58cm overall length, 11cm maximum diameter and 40cm cartridge length.

I'd like to see that drawing! For comparison, the 57mm Bofors round which is currently sitting in my lap being measured is 65cm in overall length, just under 44cm in case length, and has a rim diameter of 9.3cm.

 

[Petrus]

Here you've got photos of the 6pdr Twin mock-up.

 

[Pioneer]

I don't know, considering the irrefutable combat success and simplicity of the Soviet 57 mm AZP S-60, not did Britain just miss out on an opportunity, and it over complicated it!!

Regards
Pioneer

 

[marauder2048]

I can't recall where I read it but I swear that BuOrd had, before the end of WWII, miniaturized and test fired VT fuzes for 57mm AA. Was it for this gun?

 

[Tony Williams]

I can't recall where I read it but I swear that BuOrd had, before the end of WWII, miniaturized and test fired VT fuzes for 57mm AA. Was it for this gun?

There were no 57mm AA guns in WW2 - only AT guns. The closest to an AA gun was the British manually-loaded 6pdr 10cwt in a modified, 80 degree elevation, mounting. Postwar, the USN went straight from 40mm to 76mm for the AA role, the US Army went to 75mm (Skysweeper).

 

[marauder2048]

I can't recall where I read it but I swear that BuOrd had, before the end of WWII, miniaturized and test fired VT fuzes for 57mm AA. Was it for this gun?

There were no 57mm AA guns in WW2 - only AT guns. The closest to an AA gun was the British manually-loaded 6pdr 10cwt in a modified, 80 degree elevation, mounting. Postwar, the USN went straight from 40mm to 76mm for the AA role, the US Army went to 75mm (Skysweeper).

Doesn't imply that 57mm AA was used in WW2 just under development or planned.

 

[Tony Williams]

Doesn't imply that 57mm AA was used in WW2 just under development or planned.

If you know of any, I'd be grateful for any info. I'm trying to compile information about planned/experimental auto cannon up to 57mm calibre.

 

[JFC Fuller]

Is there any information about the 3-pounder Hogg mentions as being under development for the Navy at the time? I recall Friedman referencing a proposed 1.5-pounder but this is the first I have heard about a 3-pounder.

 

[Tony Williams]

Campbell describes a 31/2 pdr Vickers naval automatic AA gun around the end of WW2. The ammo was rather Bofors-like, fitting in between the 40mm and 57mm Bofors.

 

[Hood]

Would the 3.5pdr be connected to the 34mm DACR?

 

[Tony Williams]

No - the 31/2 pdr is 47mm calibre.

I have had replicas made up of both the 34mm Vickers Class T and the 31/2 pdr, from official drawings. The 34mm is already up on my Ammo Photo Gallery, I'll add the 31/2 pdr when I have the time.

See the last group but one on this page: http://quarryhs.co.uk/tankammo1.html

 

[Petrus]

Here you've got two photos of a Canadian high-velovity 6 pounder anti-aircraft/anti-tank gun. It was developed in 1943 from a high-velocity (and 64 calibre long barrel) version of the 6pdr 7cwt that was mounted on an AA carriage. The gun as may be seen remained hand-loaded but there were several attempts to make it automatic. The Canadians thougth of a Molins autoloader or a recoil operated autoloader with 5-round clips. The project was terminated before any of those ideas were implemented.

Piotr

 

[Tony Williams]

Excellent - I didn't know about that one!

Did it use the same ammo as the 7cwt?

 

[Petrus]

Did it use the same ammo as the 7cwt?

Robert V. Lucy in "Secret Weapons of the Canadian Army" (it is a source of the photos) says that 'the chamber was the same a the standard 6-pounder', so I think the ammo should be the same as well. Perhaps the Canadians tried different loadings, their goal were to achieve muzzle velocity around 1000 mps. They firstly built the 'Canuck' high-velocity anti-gun and then mounted it on a dual-purpose carriage.

Piotr

 

[Tony Williams]

Thank you.

 

[Tony Williams]

I have had replicas made up of both the 34mm Vickers Class T and the 31/2 pdr, from official drawings. The 34mm is already up on my Ammo Photo Gallery, I'll add the 31/2 pdr when I have the time.

I have now added the replica Vickers 3½ pdr to my photo gallery. See the last group shown here, which also includes the experimental 6pdr 6cwt round: http://quarryhs.co.uk/tankammo1.html

Also on the same page, the fourth pic up from the bottom shows the 45-57mm rounds which have seen service in automatic cannon.

 

[Petrus]

I've just had a look at photos of the gun and its mock-up. Apparently the real thing had two boxes in the front of the shield, but the mock-up lacks the boxes.
I wonder what was these boxes' function. My feeling is there are two options: (i) the boxes contained feeding mechanisms (perhaps ammunition magazines), or (ii) in the boxes there were engines for training the gun.

What do you think?

Piotr

 

[Tony Williams]

Collecting fired cases?

 

[GUNDAM123dx]

Here you've got two photos of a Canadian high-velovity 6 pounder anti-aircraft/anti-tank gun. It was developed in 1943 from a high-velocity (and 64 calibre long barrel) version of the 6pdr 7cwt that was mounted on an AA carriage. The gun as may be seen remained hand-loaded but there were several attempts to make it automatic. The Canadians thougth of a Molins autoloader or a recoil operated autoloader with 5-round clips. The project was terminated before any of those ideas were implemented.

Piotr

May I ask where does the information come from?

 

[DWG]

Here you've got two photos of a Canadian high-velovity 6 pounder anti-aircraft/anti-tank gun. It was developed in 1943 from a high-velocity (and 64 calibre long barrel) version of the 6pdr 7cwt that was mounted on an AA carriage. The gun as may be seen remained hand-loaded but there were several attempts to make it automatic. The Canadians thougth of a Molins autoloader or a recoil operated autoloader with 5-round clips. The project was terminated before any of those ideas were implemented.

Piotr

May I ask where does the information come from?

See the message by Petrus that followed the one you quoted.

 

[JohnR]

To swerve it back to the naval aspect of the gun (sorry), but if we had adopted the 57mm, particularly if a single variant had been developed, it could have provided the Type 14 a more credible armament.

 

[Yellow Palace]

To swerve it back to the naval aspect of the gun (sorry), but if we had adopted the 57mm, particularly if a single variant had been developed, it could have provided the Type 14 a more credible armament.

Unlikely, I would suggest. The Type 14 had all the armament it needed for its designed role in twin Limbo mortars and ASW torpedo tubes. Adding a bigger gun would have added cost without materially adding to capability.

If you were to propose replacing the Bofors fit with Sea Cat you might have got listened to, but I doubt whether a 57mm would have any appeal.