3in 20cwt - A trick missed?

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Paul_G_Baker
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3in 20cwt - A trick missed?

#1

Post by Paul_G_Baker » 19 Apr 2012, 23:58

This Anti-Aircraft gun was in process of being retired and replaced by the 3.7in weapon by 1941/42. It had been the preferred anti-aircraft weapon of the field army due to its rapid traverse and lower weight.

In September 1941, there was a proposal to fit 100 into limited-traverse mountings on Churchill hulls (Churchill 3in Gun Carriers) so as to be able to deal with the heaviest German tanks (of the time) - so an AP round was either already available or was purpose-designed.

When the Churchill project fell through; first having been reduced to 24 conversions because of the desire to fit all Churchill production with the new 6pdr gun, and then being cancelled entirely (most converted hulls were further modified to carry 'Snake' equipment); 50 guns were mounted in 17pdr anti-tank carriages. There are claimed to be reports that 25 of these were sent to the Middle East (although Ian Hogg says that there is no record of their employment), with the rest being retained for Home Defence.

As its performance figures feature a horizontal range of over 10,000 yards, an armour penetration of 84mm at 1000 yards with its AP Shot (better than the 6pdr and the 75mm) and it had the ability to fire HE; could it not have been employed in the same way that the Germans used their 88s?
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Re: 3in 20cwt - A trick missed?

#2

Post by Gooner1 » 20 Apr 2012, 00:06

They had them en portee in Summer 1940 already

Image

actually a naval 12-pdr but same calibre


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Re: 3in 20cwt - A trick missed?

#3

Post by Paul_G_Baker » 20 Apr 2012, 00:39

Gooner1 wrote:They had them en portee in Summer 1940 already
actually a naval 12-pdr but same calibre
Agreed on calibre, but the 3in A/A was in-theatre on land mountings (4-wheeled platforms) already and had a faster rate of fire - fixed-rounds rather than sepatate-loading.

Do you have any penetration figures for the 12pdr? Ian Hogg lists a DA (presumably Direct Action) shell, a base-fused shell (filled with gunpowder!!! :roll: ) and a solid-steel practice shot.
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Re: 3in 20cwt - A trick missed?

#4

Post by phylo_roadking » 20 Apr 2012, 01:29

Paul - Hogg says the Gun Carriage project was reduced to 25 items??? I've a recent article on them by David Fletcher laying about somewhere, I'll have to find it. IIRC he doesn't mention a reduction in the order!
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Re: 3in 20cwt - A trick missed?

#5

Post by Paul_G_Baker » 20 Apr 2012, 03:25

phylo_roadking wrote:Paul - Hogg says the Gun Carriage project was reduced to 25 items??? I've a recent article on them by David Fletcher laying about somewhere, I'll have to find it. IIRC he doesn't mention a reduction in the order!
Sorry, using two sources and didn't give the other figure! Hogg says 50 conversions and 50 on 17pdr carriages - it was C&E that claimed 100 originally ordered but only 24 completed on Churchills.

According to Hogg's performance figures, the 3in 20cwt was also way superior to the AP round fired by the 25pdrs (that one was 70mm at 400 yards at 0°, with Supercharge + Increment) - and IIRC they had to be deployed in the A/T role at one point.

Hogg's 6pdr penetration figure is 74mm at 1000 yards at 30°.

C&E cites the 6pdr as 81/83mm at 500 yards at 30° (depending on Mark) and the British 75mm as 68mm at 500 yards at 30°. C&E also cites the 77mm preformance as 109mm at 500 yards at 30°.

For the 17pdr, Hogg quotes 109mm at 1000 yards at 30°, C&E 120mm at 500 yards at 30°.

All of the above are for plain shot.

Hope we can reconcile all these numbers!
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Re: 3in 20cwt - A trick missed?

#6

Post by Gooner1 » 20 Apr 2012, 17:09

Paul_G_Baker wrote: Agreed on calibre, but the 3in A/A was in-theatre on land mountings (4-wheeled platforms) already and had a faster rate of fire - fixed-rounds rather than sepatate-loading.
The 3-inch AA was in Mid-East, with wheeled platforms? Bloody hell, why didn't they use them!
All I can think of is that there was no suitable tow? Which was a reason the Bofors 37mm A/Tk gun was preferred for a while over the 2-pdr, because the 37mm could be towed by a 15cwt truck whilst the 2-pdr needed something bigger.

The 3-inch AA gun was looked upon pre-war as a back-up anti-tank gun.

(the 12-pdr naval fired fixed rounds too)

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Re: 3in 20cwt - A trick missed?

#7

Post by Paul_G_Baker » 20 Apr 2012, 18:08

Gooner1 wrote:
Paul_G_Baker wrote: Agreed on calibre, but the 3in A/A was in-theatre on land mountings (4-wheeled platforms) already and had a faster rate of fire - fixed-rounds rather than sepatate-loading.
The 3-inch AA was in Mid-East, with wheeled platforms? Bloody hell, why didn't they use them!
All I can think of is that there was no suitable tow? Which was a reason the Bofors 37mm A/Tk gun was preferred for a while over the 2-pdr, because the 37mm could be towed by a 15cwt truck whilst the 2-pdr needed something bigger.

The 3-inch AA gun was looked upon pre-war as a back-up anti-tank gun.

(the 12-pdr naval fired fixed rounds too)
Need to do more looking to actually confirm, but it seems a safe bet that where there were mobile 3.7in later there would have been mobile 3in 20cwt earlier.

A few webpages:
http://en.wikipedia.org/wiki/File:QF_3_ ... 4.003.jpeg

http://nigelef.tripod.com/anti-tank.htm

http://commons.wikimedia.org/wiki/Categ ... nch_20_cwt

As for transport, they weighed about 3 tons - there is a very famous (1938) picture of one on Westminster Bridge which is mounted on a Peerless lorry (Ian Hogg cites it as a standard mounting).
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Re: 3in 20cwt - A trick missed?

#8

Post by Saxon Cross » 20 Apr 2012, 22:24

Regarding the penetrative ability of the 3in 20cwt, I have two sources:

"British & American Artillery of World War 2", Ian V. Hogg, A&AP, 1978, using AP Mk T2 ammo, at 30deg (assumed homogenous arour).
1000yds:
84mm

And more convincingly a War Office report WO 185/178 from 1943
Homogenous plate, AP ammo, at 30deg:
500yds: 88.5mm
1000yds: 76.5mm
1500yds: 65.5mm
2000yds: 55mm


Was this the gun used at Tobruk against tanks, or was that the 3.7in AA?


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Re: 3in 20cwt - A trick missed?

#9

Post by Paul_G_Baker » 21 Apr 2012, 03:23

Saxon Cross wrote:Regarding the penetrative ability of the 3in 20cwt, I have two sources:

"British & American Artillery of World War 2", Ian V. Hogg, A&AP, 1978, using AP Mk T2 ammo, at 30deg (assumed homogenous arour).
1000yds:
84mm

And more convincingly a War Office report WO 185/178 from 1943
Homogenous plate, AP ammo, at 30deg:
500yds: 88.5mm
1000yds: 76.5mm
1500yds: 65.5mm
2000yds: 55mm


Was this the gun used at Tobruk against tanks, or was that the 3.7in AA?


Saxon

Thanks for sharing the detailed War Office info - all I've got available is Hogg!

Found a discussion on WW2talk which points to the 3.7in being used in the A/T role in Tobruk and elsewhere; link is

http://www.ww2talk.com/forum/weapons-te ... d-gun.html

Page 2 and after. General Brooke (an Artillerist himself) was apparently taking a keen interest in using both the 3.7in and 3in 20cwt in the A/T role, but nothing I've managed to find so far confirms the earlier equipment as having actually been used in combat.
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Re: 3in 20cwt - A trick missed?

#10

Post by phylo_roadking » 22 Apr 2012, 03:42

When the Churchill project fell through; first having been reduced to 24 conversions because of the desire to fit all Churchill production with the new 6pdr gun, and then being cancelled entirely (most converted hulls were further modified to carry 'Snake' equipment); 50 guns were mounted in 17pdr anti-tank carriages. There are claimed to be reports that 25 of these were sent to the Middle East (although Ian Hogg says that there is no record of their employment), with the rest being retained for Home Defence.
Sorry, using two sources and didn't give the other figure! Hogg says 50 conversions and 50 on 17pdr carriages - it was C&E that claimed 100 originally ordered but only 24 completed on Churchills.
Paul, I at last found David Fletcher's brief article on the Churchill Gun Carriage (a shared article with the Bishop)...and it throws up some oddities with both Hogg's and C&E's accounts ;)

First - when the Bovvie team were called to a cleared gunnery range outside Folkestone just after the turn of the century, they found three Gun Carriages, with their guns dismounted...

...but all three guns were laying beside them! Fletcher notes that apart from the two factlets above, there are very VERY few concrete details still available on the Churchill...but the re-use of guns elsewhere is questionable given the "three out of three" hit rate for finding Gun carriages still acompanied by their weapons! He also goes with the 50 items constructed total...Bovington has a contract card for 49 having been assembled by Beyer Peacock locomotive builders of renown. It looks like Vauxhall built the prototype on their order for 50, then contracted the remaining 49 out to Beyer Peacock.

Also, he does specifically note that there's only a paper trail for one(1) conversion of a Gun Carriage to carry "snake" explosive piping...a prototype conversion known as the Wurlitzer! :lol: Again he notes that while some sources say some or all the de-gunned Churchills were converted this way...finding three NOT converted in one place...AND their guns!...argues against the "whole-type" conversion theory, while the paper trail only confirms the existence of one.

There's ANOTHER fact he says points against them being de-gunned ;) Look at the few available pics on them...notice anything??? :wink:

The Churchill Gun Carriages are pictured first with "T"-prefix "tank" numbers...and later they are shown with S-prefix SP gun numbers 8O Which is more indicative of them serving first with tank units....and then being given COMPLETE as assault guns to the Royal Artillery!

Given this - Fletcher produces another interesting piece of Gun Carriage history :wink: Bovington has an uncaptioned album pf photos of an exercise in Poole Harbour featuring both the only know pic of a Bishop doing anything in the UK...and several pics of Gun Carriages in various landing craft. These still have their T-numbers....and the exercise has for various reasons been dated so far to very late January or February 1943...for the pics also feature Mounbatten, and he left for the Far East in the summer of 1943.

So as late as February 1943..ish :lol: the Churchill Gun Carriages in the UK were still on paper at least with their tank A/T support role...AND their guns!...they hadn't yet been officially transferred to the RA.
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Re: 3in 20cwt - A trick missed?

#11

Post by Paul_G_Baker » 22 Apr 2012, 04:58

This thread isn't about the Gun Carrier but about mobile 3in 20cwt A/A equipments mounted on wheeled platforms; just like the 88. There were certainly 3.7in Mobile A/A deployed out there, and I feel that it's probable that a like-for-like replacement was made (certainly the army needed mobile A/A before the 3.7's arrived, but I have only been able to trace one of the batteries, they were probably a Corps or Army asset). Replacement should have left some 3in Mobile Guns available. With such a long list of Marks, the output was probably quite substantial.
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Re: 3in 20cwt - A trick missed?

#12

Post by phylo_roadking » 22 Apr 2012, 12:56

My point being - that wherever the 3in guns on carriages entries in the Middle East etc. come from, it's increasingly unlikely they came from the Churchill project as Hogg and Chamberlain&Ellis would hint broadly at.
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Re: 3in 20cwt - A trick missed?

#13

Post by Paul_G_Baker » 22 Apr 2012, 14:29

phylo_roadking wrote:My point being - that wherever the 3in guns on carriages entries in the Middle East etc. come from, it's increasingly unlikely they came from the Churchill project as Hogg and Chamberlain&Ellis would hint broadly at.
Of course not!!! Why bring back obsolescent (in its designed role) equipment from Egypt when there were already plenty of examples (which do not have had to be mobile) in UK storage/gun parks!!! :roll:

The 50 allegedly mounted on 17pdr carriages would also (logically) have been sourced from the UK stockpile, for the exact same reason!!

What's needed is a very detailed OrBat for Middle East Command, at (or just prior to) the time the Italians got frisky!!
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Re: 3in 20cwt - A trick missed?

#14

Post by phylo_roadking » 22 Apr 2012, 14:42

Not "brought back from"...
When the Churchill project fell through; first having been reduced to 24 conversions because of the desire to fit all Churchill production with the new 6pdr gun, and then being cancelled entirely (most converted hulls were further modified to carry 'Snake' equipment); 50 guns were mounted in 17pdr anti-tank carriages. There are claimed to be reports that 25 of these were sent to the Middle East
:wink:
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Re: 3in 20cwt - A trick missed?

#15

Post by Clive Mortimore » 22 Apr 2012, 17:43

Hi All

In 1940 the British did miss the chance to have a anti tank gun that would have destroyed all known German tanks at a reasonable range. I am sure it was considered being as later some barrels were mounted on the Churchill Gun Carrier.

How long would it have taken to develop a suitable carriage?
Would there have been the production capacity for a new carriage?
Could the 18 pdr or 25 pdr carraiges been used?
Would the 18 pdr MkVP carriage been the most suitable?
Were there enough spare 3 inch gun in 1940 to convert to anti-tank guns , when one considers that Britain needed as many AA guns it could get its hands on? The 3 inch did continue in service up to 1945 in some parts of the Empire.

An alterative would have been to use the gun as it stood. Now would they have been released from their AA duties by the senior officers at Corps and Army level. They did not release the 3.7 inch guns as their primary role of providing AA cover was deemed more important.

By the time the invasion panic was over the 6 pdr was in service and the 17 pdr well under development so any thoughts of a stop gap using old 3 inch guns would/should have been shelved. This now brings me to a moot point I have about the 3 inch gun on 17 pdr carriages. It was a hell of a lot of carriage for something that gave about the same bang as a 25 pdr. Another thing is has anyone seen a photo of one of these 50 guns? Like the similar over carriaged 60 7.5 cm Pak 97/40s as far as I know there is no photo.

Over to you lot

Clive
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