Sir John Valentine Carden survives.

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The other thing about the M1931 derived weapon is that it is going to be a little bit lighter and therefore more mobile than the 17pdr. Also, the ammo haulers are going to be able to carry more ammunition per load, so it's going to be easier to support logistically as well.

I get the feeling that the 17pdr 76.2mm L55 gun tube might get necked out to 83.5mm with an L50 gun tube during its development while retaining the 583mm cartridge case and corresponding breech mechanism in an attempt to match the German 88mm guns in the Tiger.
 
thats why im suggesting 20 pounder since vickers gun is basicly a 17 pounder but abit inferior wich isnt a disaster to be honest and will probably have better HE capability . The royal artillery should try to do that and skip the straight 3inch range to 20 pounder wich was 84mm in the centurion i think is my suggestion . Its also a nice option for a late mark victor or even the centurion equilevant tank wich would be rather helpful actually aswell .
 
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With regards to India, ITTL, it will still become independent (the groundwork for that is not affected by the PoD, IMO), but it will be different--it depends on how well the Burmese front does in World War II--I could easily see it becoming its own theater (PM @Fearless Leader for more information--he did this in his excellent Wake Island TL)...
 
Yeah singapore is probably going to fall but doing better in that campaign is very possible especially if some tanks can be sent . Maybe a matilda brigade ? But the bigger chance and wich might matter abit more is burma campaign . The americans were actually interested in supporting burma compared to other british colonies since it held the only connection to china .
 
I took that upgrade in a different way - I read it as RA saying 3" M1931 isn't good enough and we need a TTL 17 pdr equivalent. That may be a case of Not invented Here but the probability of the M1931 based guns being available late 1941 compared to 1943 at the earliest for 17 pdr suggests that a good enough now (M1931) is better than waiting for the best (17 pdr).

I'd be interested to know what tank is going to be standing up to the 6pdr before 43 that the British are going to see in numbers?

20pdr is going to be way to big and heavy to actually be useful as a towed antitank gun, plus it's a wee bit overkill considering that the majority of tanks that the British will fight against will be panzer 4s with the odd smattering of Panthers and Tigers.

if you want the best use of resources for towed AT guns, bin off anything apart from the 6pdr and develop the Sabot round earlier. if you find anything that the 6pdr cant handle then you give Division a tinkle and get the 25pdrs to take care of it.
 
I took that upgrade in a different way - I read it as RA saying 3" M1931 isn't good enough and we need a TTL 17 pdr equivalent. That may be a case of Not invented Here but the probability of the M1931 based guns being available late 1941 compared to 1943 at the earliest for 17 pdr suggests that a good enough now (M1931) is better than waiting for the best (17 pdr).
That was the way I meant it. The Director of Artillery is thinking more of towed anti-tank guns for the Royal Artillery anti-tank gun Regiments, whose sole job is punching holes in tanks. Vickers are thinking about a tank gun with dual AP/HE. It is my reading of the material that a half-decent HE capability isn't easily compatible with the best AP capability. So the desire for what will become the 17-pdr is pure anti-tank. Vickers have been listening to the tankies who found the lack of a decent HE round problematical. The 3-inch gun based on the Model 1931 75mm AA gun is a compromise too far for Clarke, who needs to think about the towed AT gun after the 6-pdr.
I guess what I'm trying to avoid here is the OTL mess: 2-pdrs kept on too long. American tank 75mm with HE are a revelation. 6-pdr replaces 2-pdr, but needs to also be made into the QF 75mm, but then you need 17-pdr Fireflies plus the 77mm HV for the Comet. So British tank formations had a variety of tanks late war, with American Shermans 75mm, British QF 75mm, Shermans with 17-pdrs and Comets with 77mm HV. Not forgetting the 95mm CS howitzer.
If the Valiant I is 2-pdr, the Valiant II is 6-pdr; then the Victor I is Vickers 3-inch with decent HE/AP which should do until the tank after the Victor comes along with ????
The issue will be the Germans having faced the 2-pdr in France have up-armoured and gunned their Pz III and IV. If they experience a Valiant 6-pdr in 1941 and a T34/KV2 then their own development cycle is going to step up. The Vickers 3-inch/17-pdr will be needed, as will the guns after that.
 
I don't understand why the 2500 fps figure keeps being brought up, as IIRC it was 2650 fps for the 75 HV, resulting in 87mm @30° @1000 yards/m penetration so slightly better than the 3" 20cwt on the Churchill GC. Using the 75mm caliber made sense since the 17pdr was just entering production while the Brits could get a supply of 75mm projectile through the US, with the 3" 20cwt 12.5 pound shell likely being rare.

What I never got is why the British didn't fit that in a Sherman concurrently with the Cromwell, or even if the latter failed to take the gun? Surely it would have been a better fit than a 17pdr and still an improvement in performance, indeed similar to the US 76. Did they not want to waste the M3 guns that were delivered in Shermans (but then why not sell the idea to the Americans or ask for gunless Shermans once it's known the 75 HV gun will be fitted?)?
The 2650ft/s muzzle velocity is for the 77mm HV, not the 75mm HV. I have seen a few sources cite 2500ft/s for the 75mm HV including Fletcher so I am pretty sure that is correct. That too me has always been part of the mystery of that gun, why was the MV so low for the 75mm version considering the shells were over 2 pounds lighter than the 77mm. My working theory is that the US 75mm ammo could not be safely fired faster than 2500ft/s so that was the MV they went with, then, when the switch to 17 pounder ammo happened they went all out because they could. No proof on that though.

The idea of using US ammo because it is available is an OK one but it seems incomplete to me. Britain never made 75mm ammo as far as I can tell in any significant quantities. What it did make and was making a lot of at the time is 3" ammo so if Britain was going to supply it's gun with ammo 3" would be a far easier calibre to choose. Besides ammo will have to be produced for the gun in some form, whether it be by taking US 75mm projectiles and putting them in a 420mmR case or by building new 3" ammo. Either way that has to be accounted for and making a few more 17 pounder shells was obviously no big issue to Britain because that is the version that actually saw combat.

Fitting the 75mmHV into a Sherman was I suspect the plan from the start, though in every Sherman, not just the odd one like the firefly. That too me makes the most sense as to why the US 75mm ammo was chosen, design the gun, put it in a tank and show it working, get the Americans to start building the gun and put it in Sherman's. The problem was that as soon as the 75mm would not fit into the Cromwell that realistically died. Then putting it into the odd Sherman is just adding another calibre to the ever growing list of calibres needing to be supplied. With the Firefly you not only have a better AT gun but also only 1 type of ammo needed. I also think that there might have been a growing realisation in Britain that America was moving away from British influence on tanks etc by 43 so the chances of that happening were slim to non. Thats why the Comet got a gun using British standards.
 
My 'Darling' for an early war or even pre-war 3" British DP gun system is a then modern version of the 3" 9CWT (457 kgs) - that's just the gun bits (for comparison A 2 pounder gun - Not including carriage - is 109 kgs and the 6 pounder is 345 kgs)- an adaptation of the WW1 '13 pounder' AAA gun.

A combination of 13 pounder Barrel and 18 pounder cartridge firing a 5.7kg/12.5 ib shell at about 2000 FPS (that in 1916) and was used for HE throwing and so had a legacy HE shell.

I know its too perfect but its my go to DP tank gun for the UK
 
That was the way I meant it. The Director of Artillery is thinking more of towed anti-tank guns for the Royal Artillery anti-tank gun Regiments, whose sole job is punching holes in tanks. Vickers are thinking about a tank gun with dual AP/HE. It is my reading of the material that a half-decent HE capability isn't easily compatible with the best AP capability. So the desire for what will become the 17-pdr is pure anti-tank. Vickers have been listening to the tankies who found the lack of a decent HE round problematical. The 3-inch gun based on the Model 1931 75mm AA gun is a compromise too far for Clarke, who needs to think about the towed AT gun after the 6-pdr.
I guess what I'm trying to avoid here is the OTL mess: 2-pdrs kept on too long. American tank 75mm with HE are a revelation. 6-pdr replaces 2-pdr, but needs to also be made into the QF 75mm, but then you need 17-pdr Fireflies plus the 77mm HV for the Comet. So British tank formations had a variety of tanks late war, with American Shermans 75mm, British QF 75mm, Shermans with 17-pdrs and Comets with 77mm HV. Not forgetting the 95mm CS howitzer.
If the Valiant I is 2-pdr, the Valiant II is 6-pdr; then the Victor I is Vickers 3-inch with decent HE/AP which should do until the tank after the Victor comes along with ????
The issue will be the Germans having faced the 2-pdr in France have up-armoured and gunned their Pz III and IV. If they experience a Valiant 6-pdr in 1941 and a T34/KV2 then their own development cycle is going to step up. The Vickers 3-inch/17-pdr will be needed, as will the guns after that.
I will die on the hill of the Vickers 3" being underpowered for what it is. I think it has gotten to the point it's my thing now on this timeline.
Anyway a slight modification of your British WW2 tank gun Timeline
  • 2pdr is it and all is good. Does well as both AT and Tank gun if you ned to put holes into something.
  • Realise something bigger is needed so start on the 6pdr
  • 6pdr is delayed by Dunkirk so 2pdr soldiers on
  • 6pdr arrives, but wont fit in any of the tanks. Oops.
  • US tanks arrive with 75mm guns, hey good HE is pretty handy
  • 6pdr is made to fit into tanks, we still really like good AP performance too you know
  • What gun should arm our next tank?
    • Hang on maybe we should stop building tanks and just use american tanks?
    • Actually no lets keep building tanks
  • We have made this 6pdr able to take the US 75mm ammo, it's got really good HE you know.
  • OK, we will keep that under advisement what we really want is that new gun from Vickers, Its got Good HE and Good AP so that's out new gun and all is well
  • Bugger, it wont fit. Again. You really think we would learn wouldn't you.
  • Can we fit a 17pdr in a tank? What do you mean no? are you sure. We've done it again haven't we? can we make it fit?
  • OK guess we will use the ROQF 75mm then
  • Lets make a new tank to take the Vickers gun but lets also make the gun more powerful because we're British and really good AP is what we do.
  • We like this new tank, lets cal lit the Comet. We really like it's new gun as well. It's going to be brilliant.
  • Oh the wars over.
  • Oh by the way, here's Centurion, it has the 17pdr and it actually fits. We call it a Main battle tank.
And to think, things started so well with the 2pdr and if the 6pdr had been even a couple of month's earlier then most of this could have been avoided. Also not I avoided all the CS howitzer stuff because that is its own thing as well. I do agree that the Germans are, in all likelihood going to step things up. Again to slowly and painfully die on this hill, the 3" should be more powerful than the Kwk 40, like 77mm powerful, if it is to be a true British gun of the WW2 era.
 

marathag

Banned
20pdr is going to be way to big and heavy to actually be useful as a towed antitank gun, plus it's a wee bit overkill considering that the majority of tanks that the British will fight against will be panzer 4s with the odd smattering of Panthers and Tigers.
20 pounder tube and breech would be with a few pounds of the 17 pdr. The real problem of powerful AT guns, is the ever increasing weight of the carriage.

The recoil energy of the 20 pdr is 4.54K Joules, that's more than two PaK 40s or a thrid more than a 17 pdr going off at the same time, and just a bit less than a Soviet 152mm howitzer.
1613843279946.jpeg

That's of energy on an 8 ton vehicle, with a 90mm with just a bit more ME than the 20 pdr
 
I will die on the hill of the Vickers 3" being underpowered for what it is. I think it has gotten to the point it's my thing now on this timeline.
Anyway a slight modification of your British WW2 tank gun Timeline
  • 2pdr is it and all is good. Does well as both AT and Tank gun if you ned to put holes into something.
  • Realise something bigger is needed so start on the 6pdr
  • 6pdr is delayed by Dunkirk so 2pdr soldiers on
  • 6pdr arrives, but wont fit in any of the tanks. Oops.
  • US tanks arrive with 75mm guns, hey good HE is pretty handy
  • 6pdr is made to fit into tanks, we still really like good AP performance too you know
  • What gun should arm our next tank?
    • Hang on maybe we should stop building tanks and just use american tanks?
    • Actually no lets keep building tanks
  • We have made this 6pdr able to take the US 75mm ammo, it's got really good HE you know.
  • OK, we will keep that under advisement what we really want is that new gun from Vickers, Its got Good HE and Good AP so that's out new gun and all is well
  • Bugger, it wont fit. Again. You really think we would learn wouldn't you.
  • Can we fit a 17pdr in a tank? What do you mean no? are you sure. We've done it again haven't we? can we make it fit?
  • OK guess we will use the ROQF 75mm then
  • Lets make a new tank to take the Vickers gun but lets also make the gun more powerful because we're British and really good AP is what we do.
  • We like this new tank, lets cal lit the Comet. We really like it's new gun as well. It's going to be brilliant.
  • Oh the wars over.
  • Oh by the way, here's Centurion, it has the 17pdr and it actually fits. We call it a Main battle tank.
And to think, things started so well with the 2pdr and if the 6pdr had been even a couple of month's earlier then most of this could have been avoided. Also not I avoided all the CS howitzer stuff because that is its own thing as well. I do agree that the Germans are, in all likelihood going to step things up. Again to slowly and painfully die on this hill, the 3" should be more powerful than the Kwk 40, like 77mm powerful, if it is to be a true British gun of the WW2 era.
The Vickers 3" can be in tanks in late 41/ early 42. It is more than enough for anything the Germans have until the Panther is deployed. The Tiger will never be common enough to be of particular concern. By the time the 3" is getting too old there will be another gun available, either the 17 pdr or something heavier.
 
It is more than enough for anything the Germans have until the Panther is deployed.
I understand late-war Panthers were unusually susceptible to HE rounds because of improper face hardening, a gun in the general 3" or bigger range should still be sufficient, even with a lower muzzle velocity.

I fear a search for an 'optimal' tank gun will lead to unfortunate results, @allanpcameron has so far been very reasonable with his design choices, having sufficiently future-proofed British tank production so far and for the foreseeable future. I trust he has already made a decision on a weapon 'good enough' for wartime service, one he has already been laying the foundations with the 1931 gun (ultimate incarnation of which TBD).

So fear not! The Valiant is already the king of the early war armoured services, early glimpses at the Victor have hinted at a machine able to close out the war. It's going to be interesting what other vehicles get developed thanks to Britain's solid foundations in development!
 

perfectgeneral

Donor
Monthly Donor
Perhaps inspired by recent armoured points of departure from history sonofpegasus has posted an update about defending Malta that raises some interesting ideas about field adaptations. Link to post

I wonder if a spade/shovel attached to the front of universal carriers or APCs might prove useful?
 
The Vickers 3" can be in tanks in late 41/ early 42. It is more than enough for anything the Germans have until the Panther is deployed. The Tiger will never be common enough to be of particular concern. By the time the 3" is getting too old there will be another gun available, either the 17 pdr or something heavier.
It's not really a question of performance, if it's even a bit better than the KwK 40 then it's good enough. It's more that throughout the war and before Britain made it's AT/tank guns as good at punching holes as possible. In my head at least for Vickers to try and get the Army interested they would focus on hole punching and then do as much as possible to make the HE as good as possible. Thats even more true given that the gun was started pre war before the HE issue had started to become an issue for the army.
 
There has been mentions of guns referring to the shell weight and of him types as 17 Pounder etc. It may be worthwhile to remember that the British 'Pounder' method refers to the weight of a lead sphere of the same diameter as the bore. It has nothing to do with the weight of any shell used. Also the reason 75mm was chosen for the QF75mm was so that all Wallied tanks in Overlord used the same (US) ammunition to ease logistics.
 
There has been mentions of guns referring to the shell weight and of him types as 17 Pounder etc. It may be worthwhile to remember that the British 'Pounder' method refers to the weight of a lead sphere of the same diameter as the bore. It has nothing to do with the weight of any shell used.
And yet the 2 pounder, 6 pounder and 17 pounder all had their main ammunition at that stated weight. I am unsure if this was simply a happy coincidence or not but my understanding was that it remained British practice to name smaller guns by the weight of the actual shell they fired, rather than it being a throwback to Roundshot.
 
And yet the 2 pounder, 6 pounder and 17 pounder all had their main ammunition at that stated weight. I am unsure if this was simply a happy coincidence or not but my understanding was that it remained British practice to name smaller guns by the weight of the actual shell they fired, rather than it being a throwback to Roundshot.
It definitely was not, originally in the days smoothbore muzzle loader, guns were rated by the solid lead sphere method but afterwards it was the weight of its normal ammunition projectile. An example of this is the famous 68 pounder cannon , arguably the best smoothbore every built. As a smoothbore it was rated at 68 pounds but when later some were relined to become RML ( rifled muzzle loader ) despite the reduced bore ( due to the added lining ) , they became 80 pounders as that was the weight of the new shells.
 
22 November 1940. Sidi Haneish, Egypt
22 November 1940. Sidi Haneish, Egypt

Major-General Creagh and his senior staff had spent the last few days getting to know the men and machines of the 2nd Royal Gloucestershire Hussars (RGH) and 3rd Sharpshooters, (County of London Yeomanry). The men were no longer quite so fresh out of England, their sunburn not quite so painful. While their tanks had gone through the process of preparing them for the harsh environment of North Africa, the men had been exercising in body and mind. A long sea voyage had wasted away some of their fitness and part of their acclimatisation to Egypt had been marches and runs at all times of the day and night. The men of the Regiments weren’t that keen on all the physical aspects, other than sports, but they were well disciplined and began to feel that ‘they’d caught their breath’ in their new surroundings.

The mental exercises had been much more challenging and enjoyable. A detachment of 7th Armoured Division’s men, especially some of the old hands, had been teaching, as far as practicable, some of the skills and abilities that would be needed in desert warfare: first and foremost, the importance of learning navigation skills without much in the way of landmarks on maps. The tank commanders were particularly focussed on this, but drivers, gunners and loaders were all taken through the skills to figuring out where they were and how to get where they should be. Their teachers had spent years in ‘the blue’ and knew that navigating in the desert could seem as much an art as a science.

There were lots of tricks that soldiers had learned to make life bearable in an inhospitable climate: How to make the most of the water ration; looking after yourself and your equipment; what to look out for; what to do in sand storms; all these survival techniques could be taught and shared, but only experience would drive the lessons home.

Now that the men and the tanks had had a month to prepare themselves Creagh was getting them ready for the first full Divisional training exercise that was due to take place in a couple of days. The two Yeomanry Regiments had a good working relationship as part of 22nd Armoured Brigade. Creagh had had to give a lot of thought, along with his Brigadiers John Caunter (4th Armd Bde) and Hugh Russell of (7th Armd Bde), to how best integrate them into the Division. Brigadier John Scott-Cockburn, whose 22nd Brigade HQ was now awaiting the arrival of the rest of 2nd Armoured Division, had suggested keeping the two regiments together in one Brigade, since they were used to working alongside one another. Creagh, however, on inspecting the tanks and the men, thought it would be better to have one regiment of these tanks in each Brigade.

4th Armoured Brigade would therefore consist of 6th Battalion RTR, 7th Hussars and 2nd RGH. 7th Armoured Brigade would comprise 1st Bn RTR, 8th Hussars and 3rd Sharpshooters. The mixture of light and cruiser tanks in the original four regiments had stabilised with the majority of being made up of A9 and A10s, but there was still up to a squadron of Light Tanks in each Regiment. This was in some part deliberate, going back to Hobart’s time in command of the Mobile Force (Egypt). In the days when there were few tanks capable of taking on other tanks, mixing some 2-pdr Cruisers in with the majority of Light Tanks made sense.

Creagh wanted some experienced desert men in with the new Regiments, just in case. The 2nd RGH and 3rd Sharpshooters HQs swapped out a couple of their Valiant I* for Light Tanks with experienced officers. Having the 22nd Brigade HQ tanks available was also really helpful. Their ten Valiant I*, along with those from the two Regimental HQs, gave each of the original four Regiments a troop of the new tanks.

The 7th Armoured Division's workshops nearer Marsa Matruh had been just as busy as those back at the Delta. The new air-filters had been fitted all the A9 and A10s, in addition, all the A10s had been fitted with the new extra external fuel tank. The A9s were due to get theirs once more became available. Every tank had been serviced as much as possible and as far as the leadership of 7th Armoured Division could see it was the strongest it had ever been. As always, the Workshops had a few non-runners to deal with, and the Depots had some spare tanks for replacements, but otherwise the Division was ready to go to war.

NB Text in italic differs from OTL. I can't find anything that actually talks about the merger of OTL 2 RTR (cruisers) and 8 Hussars (lights) into the two armoured Brigades, but obviously it happened, something like this (I hope). The mixing of cruisers and lights happened more then than it does this time. OTL 6 December 1940 4th Armoured Brigade looked like: 7 Hussars 4 cruisers/34 lights; 2 RTR 36/16; 6 RTR 16/17. 7th Armd Bde: 3 Hussars 16/36; 8 Hussars 4/34; 1 RTR 16/22, with 47 cruisers and 82 lights in workshops/depots. Obviously the fixing up of tanks was going on up to the last minute. The 11th Hussars, Western Desert Force's reconnaissance unit, are also floating around in Light Tanks and Armoured Cars, reinforced with an extra squadron from No.2 Armoured Car Company R.A.F. from Palestine. Here, roughly, 7th Armoured Division is at full strength (War Establishment 340): 4th Armd Bde: 7 Hussars 36 cruisers/16 lights; 2 RGH 50/2; 6 RTR 44/8. 7th Armd Bde: 3 Hussars 36/16; 3 Sharpshooter 50/2; 1 RTR 44/8. In addition, each Brigade HQ has 6 cruisers/ 4 Lights (OTL 2/8), plus Division has another 4/4 (OTL 1/5). The plan OTL, which I'm presuming also happened TTL, as A10s arrived they would go to the RTR regiments, who'd pass their A9s onto the Hussars. So RTR cruisers are mostly A10 (~80), the Hussars are mostly A9 (~70), plus RGH & Sharpshooters Valiant I*(100). The Italians are believed to have 144 mediums and 60 light tanks!
 
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