Tank & AFV armament alternatives, 1935-45

[tomo pauk]

There are 3 ways to make 'better' AP ammo.
1. Make better AP shot (better heat treatment, add piercing cap, add ballistic cap, change weight)
2. Increase velocity (new powder, higher pressure, larger chamber/more powder)
3. Change type of projectile (HEAT, APCR, etc)
Some of these are somewhat time dependent. When do the better powders show up? When did HEAT (shaped charges show up).

HEAT will probably feature more in the later guns, and it didn't amounted much for the British. Italians and Germans made a wider use of the HEAT, and after 1940?
For the kE (kinetic energy) projectiles that obviously everyone used, indeed all the 3 suggestions are valid. Specifically for the British, earlier experimenting with the APC, APCBC and APCR ammo would've yielded handsome returns. See also how much the cartridges can be hotter loaded for the legacy guns to be still on the safe side. At any rate, the hotter ammo will not represent more than 10-15% of what the tank ammo count. 'Hotter' being a result of either the increased propellant charge in the existing casing, or the introduction of more modern propellants.

Sometimes you can make a better new gun/ammo than trying to up grade an old gun to do about the same thing. Both steel and powder technology were advancing in the 20s and 30s. Picking an older gun with the idea it can be modified or upgraded at a later date instead of designing a new gun that pretty much does what you want (velocity for weight of gun)
may not have been a good idea.

The 6pdr 10cwt is already a thing before 1935. Every ammo development carried out for the earlier gun can be used for it.
Fitting of the 12-13 pdr guns was suggested many times. Either of these bigger guns will be an easier and better fit to the tanks/turrets designed for the early 6pdr guns, than on the tanks/turrets designed for the 3pdr, let alone for the 2pdr.

British actually did pretty good with the light tanks
Pretty much the King of the 5 ton tanks. 3 man crew. Commander was not the gunner. It had a radio (2 way!) it was zippy. It had a fair chance of killing other 5 ton and smaller tanks.
Something that could not be said of many other 5 ton tanks. Almost 1700 of them built which was the big mistake. It doesn't matter how good a light weight boxer you are when you come up against even just a competent middleweight.

The Vickers light tank would've been great as a waffentraeger - carry the AA guns (hoefully the pintle-mounted 15mm or an Oerlikon can fit), or a good mortar, or howitzer, or an anit-tank gun. Also an APC.
Be it as-is, or stretched by one half bogie.

 

[tomo pauk]

Some options for Germans:
- a single-shot 30mm for the Pz-II and/or Pz-38(t); granted, the earlier these two became the self-propelled mounts for some serious guns, the better
- the French or Czech 47mm guns for the Pz-III
- the 52mm gun from ww1 for Pz-III and/or -IV, a spin-off from this gun (means that the 5cm L60 is not conceived)
- see whether the short 75mm gun can be modified to fire the more powerful ammo from the 7.5cm mountain gun (extra 100 m/s can be gained), retrofit the muzzle brake will be probably required
- the Polish/French/German more substantial 75mm guns for the Pz-IV and StuG-III were already suggested
- the Tiger's or the Panther's gun on the Nashorn/Hummel base for 1943, better armored than the Nashorn
- 7.5cm L60 Flak turned into an AFV gun from 1935 on

Obviously, going for some guns means that other guns don't get the chance.

 

[EwenS]

The Vickers light tank would've been great as a waffentraeger - carry the AA guns (hoefully the pintle-mounted 15mm or an Oerlikon can fit),

Which version do you prefer?

Vickers light AA Mk II tank ("Ack ack" Mk II light tank) - case report

Keep eyes on the Stukas, lads!!! This article is about the late operational anti-aircraft version of the Light Tank Mk VI, built by Vick...

panzerserra.blogspot.com

or a good mortar, or howitzer, or an anit-tank gun.

For which there was the Bren/Scout/Cavalry carrier of pre-war years that became the Universal Carrier in WW2.

Universal Carrier - Wikipedia

en.wikipedia.org

WW2 saw versions to carry the Vickers MMG and 3" mortar (it could be fired from the commander's compartment as well as the usual dismounted option) as well as a gun tower for the 6pdr AT gun. All sorts of extemporised weapon fits were made to these vehicles in WW2 by various armies including the Germans. Single 0.5" Browning, single 20mm Solothurn AT gun, triple Panzerschreck amongst others.

There were experimental versions fitted with a 2pdr. The Aussies had their own version and produced 200 for training as well as a specialist mortar carrier along the same lines.

https://upload.wikimedia.org/wikipedia/commons/9/96/2_pdr_Aust_ATG_carrier%28AWM_134672%29.jpg

Later in WW2 enlarged versions of the Universal Carrier were produced in the USA (T16) and Canada (Windsor carrier)

Universal Carrier T16

Universal Carrier - Wikipedia

en.wikipedia.org

Also an APC.
Be it as-is, or stretched by one half bogie.

The Loyd carrier began life in 1939 as a troop carrier, before moving on to other roles. It became the main vehicle for towing the 6pdr AT gun in infantry divisions in NWE.

Loyd Carrier - Wikipedia

en.wikipedia.org

All these vehicles used similar suspension components to the Vickers light tank series of the inter-war period.

 

[MikeMeech]

Actual photos of the T-26-4 seem scarce. Of course the Soviets were building light tanks with twin turrets
View attachment 808659
either a mg in each turret or a short 37mm in one turret and a mg in the other. Machine guns were pretty much the 'go to' solution for soft targets.
Lack of actual experience?

The 2pdr gun itself was not bad, the decisions not to give it HE ammo, capped ammo and geared elevation/better sight is what crippled it in use in 1939-41 and if you put those limitations on any other caliber weapons you would have suffered similar results.

Hi
The Soviet T-26 details contained on page 215 of the same source as I mentioned in Post#20 previously:

As mentioned it was based on a Vickers design, the Soviets having a licence to build Vickers designs from 1930, the British original from page 83 of same source:

The USA was also designing MG equipped tanks, from page 172 of source:

And, as previously posted, the M2A1 also had lots of MGs in 1939-40:

Extra MG turrets was quite popular in tank design in the 1930s amongst many nations for anti-personnel use, for example in the pre-war British Cruiser Mark I (A9),

Source: Page 43 of 'British Tanks' by B T White.
Mike

 

[Shortround6]

HEAT will probably feature more in the later guns, and it didn't amounted much for the British. Italians and Germans made a wider use of the HEAT, and after 1940?
For the kE (kinetic energy) projectiles that obviously everyone used, indeed all the 3 suggestions are valid. Specifically for the British, earlier experimenting with the APC, APCBC and APCR ammo would've yielded handsome returns. See also how much the cartridges can be hotter loaded for the legacy guns to be still on the safe side. At any rate, the hotter ammo will not represent more than 10-15% of what the tank ammo count. 'Hotter' being a result of either the increased propellant charge in the existing casing, or the introduction of more modern propellants.

A large problem for the British (which should have been corrected) was that they weren't spending money on all sorts of things like research and testing. As has been noted many times elsewhere they shoved the drawings for the 100lb Anti-sub bomb in a drawer in the 1920s and then didn't make an actual sample until 1938(?) and then only exploded it in open air, not against a submarine hull. even an old rusty one.
In any case, 600m/s is around the threshold of shot needing a piercing cap and this is impact velocity, not MV so nobody was making capped shot for any of the field guns or some of the old naval guns.

A major problem with "hot" loads has absolutely nothing to do with either the 'load' or the guns. It has to do with both training and sights. The "hot" loads will have a different point of impact. Which can be solved with training. (fake British accent) "By Jove, The cost of live fire training is simply too expensive to contemplate". Or new sights/telescopes with added aiming marks and we can guess what the treasury will think of that. Or a combination of the two, the best solution.

You often need new propellants. When a gun is designed they usually do not have room for extra propellent. That is wasteful of cartridge materials and extra space usually means irregular burning/combustion which leads to variations in MV which leads to inaccuracy at longer ranges. Guns that got new powder often got wads or spacers to keep the powder in the smaller space.

The 6pdr 10cwt is already a thing before 1935. Every ammo development carried out for the earlier gun can be used for it.
Fitting of the 12-13 pdr guns was suggested many times. Either of these bigger guns will be an easier and better fit to the tanks/turrets designed for the early 6pdr guns, than on the tanks/turrets designed for the 3pdr, let alone for the 2pdr.

The mechanics of getting shells/shot to penetrate armor had been being worked on for about 60 years by the early 1920s. Any gun maker worth his pouring furnace already knew about plain shot, piercing caps, ballistic caps, and they knew that somethings didn't work/were not needed at certain velocities. Nobody was going to spend any time working on fancy penetrating shot for the old guns/shot as outlined above.
The bigger guns may make for satisfactory HE throwers but the powers that be can do the math and with conventional AP shot (even APCBC ) they are an expensive way to get armor punching performance. Expensive in terms of the weight of the guns and volume required to house the gun and a worthwhile supply of ammo.
Now as an indication of this, some sources (open to correction) show the Russian BT-7 holding 146 rounds of 45mm ammo. Sources vary, exact model varies and fitting a radio affects ammo supply. Changing to the 76.2mm/L16.5 weapon (gun?) means the ammo supply drops to 40-50 rounds (depending on radio?) American M 5 light tank holds 147 rounds of 37mm ammo. The M 8 SP 75mm pack howitzer holds 48 round.
You want a big gun? you need a big tank. Big tank = Big money.

The Vickers light tank would've been great as a waffentraeger - carry the AA guns (hoefully the pintle-mounted 15mm or an Oerlikon can fit), or a good mortar, or howitzer, or an anit-tank gun. Also an APC.
Be it as-is, or stretched by one half bogie.

The Vickers light was a very useful learning tool. As a combat vehicle (tank) it was not a good bargain. Or rather it's usefulness varied widely depending on how dumb you opponents were. Against the already mentioned Italian tankettes it was the Lord and Master. But against 10 ton tanks it was near useless.
Or even these

8.2 short tons, one man turret but 12mm armor all the way around which means the Vickers tank with it's .5in gun needs to be both very close and lucky.
Now the Japanese could have made a much more effective tank by changing a few things. Take the machine gun and gunner out of the hull. Make the hull large enough to hold a two man turret, get rid of the machine gun sticking out the back of the turret (having a one man turret is bad enough, having the cannon and machine gun point in different directions has our one man wallpaper hanger commander trying to do everything while balancing on one leg). Mount the MG co-ax with the cannon. Make the commander the loader, Put some vision blocks in the cupola. Not even asking for a radio While the gunner is doing his think the commander has time (ha-ha) to either look for the platoon commanders signal flag/s or if he is the platoon commander to wave his own flags while his command tank maintains reduced fire.

 

[Shortround6]

If we review the British tank history with the 2pdr gun it was first used in the A9

14.4 US tons, 14mm armor, 6 men
2pdr 100 rounds
3 Vickers guns 3000rounds
25mph (? down hill?) 9.64 litre AEC bus engine
There is a lot to criticize but very few people were doing any better.

16 (s) tons, 30mm armor (not everywhere) 5 men
2pdr 100 rounds
2 Besa guns 4050rounds
16mph 9.64 litre AEC bus engine

Now the British have got a few problems, like shit for tank engines.
Trying to up grade from the 2pdr to a 6pdr, of any short, has problems.
We can see from the two tanks above that increasing weight by about 1.5 tons has significant performance impact. As already mentioned, it is not just the weight of the tube, it is the weight of the entire turret. This can be complicated by staff requirements like elevation and depression limits (often relaxed when up gunning existing vehicles) which can affect turret roof height.
Now the British had a few solutions in the works

15.7 (s) tons, 14mm armor 4 men
2pdr 87 rounds
1 Vickers gun 3750 rounds
30mph 340 Liberty engine.

Engine problem solved (cough/ cough). Turret problem might be solvable (a little bigger)
But some how we lost both a crewman and 13 rounds of 2pdr ammo. Where does bigger ammo go?

By the time you get to the Crusader you have a 21-22 ton tank that holds 110 rounds of 2pdr ammo but only 65 rounds of 6pdr ammo (bigger than the old 6pdr ammo)
and you are down to 3 men instead of 5 (perhaps they could have rearranged stowage a bit better).
The later Cruisers with the 6pdr got much thicker armor and got 1-2 crewmen back but about the same ammo.

You could design a tank to hold one of the older 6pdrs but to hold 4-5 men and the desired amount of ammo you need a bigger tank, even with only 30-40mm armor.
Which means more money=fewer tanks.
And you still have not figured out the poor vision and poor ammo selection (6pdr offers more HE potential if you can change doctrine) or the poor aiming choice or the poor sights or the fact that unless you used the 6pdr 10cwt you don't come close the flat trajectory of the 2pdr to help with the poor sight/shoulder aiming problem. Maybe they give up on the shoulder aim when faced with an over 1000lb (480kg) gun tube?

 

[Shortround6]

Some options for Germans:

Captain contrary at the ready

- a single-shot 30mm for the Pz-II and/or Pz-38(t); granted, the earlier these two became the self-propelled mounts for some serious guns, the better

This depends on what you want to do.
The MK II was a sort of in-between tank. It doesn't get quite enough credit for the 20mm gun. Think of it like a modern tank/AFV with one man turret with a auto-loading gun using easily replaceable ammo cassettes
Having one man turret still sucks but having 10 shots for an auto-loading semi-auto gun beats the heck out of some of the single shot guns for repeated shots or engaging several closely grouped targets. Early German doctrine (manual) called for AP against hard targets and MG against soft target. AT gun with shield was a hard target, When flanked and being shot at from the side (crew) it was a soft target.
Granted having a two man turret with the same gun/s is even better.

Pz-38(t) has a problem, it carries around 60% (estimate) of the 37mm ammo of the Pz IIIE & F and a similar amount of MG ammo (2400 rounds (?) vs 4500 rounds.
You can make a better AT vehicle out of it, it may not be a better infantry support vehicle or better recon vehicle.
Now biting the bullet and making the chassis about .5 meters wider like they did to the Hetzer offers a lot of possibilities. don't wait until the spring of 1944.

- the French or Czech 47mm guns for the Pz-III

Neither offers any real advantage over the 5cm/L 60.

- the 52mm gun from ww1 for Pz-III and/or -IV, a spin-off from this gun (means that the 5cm L60 is not conceived)

Ok, we all hate the Germans. At some point just start over and not try to update a gun from 1905.
The Data in NavWeap has the decimal point in the wrong place. Gun is 380kg.

- see whether the short 75mm gun can be modified to fire the more powerful ammo from the 7.5cm mountain gun (extra 100 m/s can be gained), retrofit the muzzle brake will be probably required

Waste of engineering time. Don't creep up on the more effective gun, just go for it. Germany doesn't have the engineering capacity to waste on some of the ideas it was already pursuing

- the Polish/French/German more substantial 75mm guns for the Pz-IV and StuG-III were already suggested

Much like the above. And decide what you want the Stug-III to do. Early war it was artillery support, sit back from the battle and lob shells in. It had artillery type sights and there was at least one forward observer per platoon (in an armored 1/2 track). It could get in close for direct fire but that exposed it to direct fire.

- the Tiger's or the Panther's gun on the Nashorn/Hummel base for 1943, better armored than the Nashorn

You could even have the 8.8cm/L56 in the Spring of 1942.

Swap 88mm for the 105mm.

- 7.5cm L60 Flak turned into an AFV gun from 1935 on

Might have speeded up the Panther project.

 

[tomo pauk]

You could design a tank to hold one of the older 6pdrs but to hold 4-5 men and the desired amount of ammo you need a bigger tank, even with only 30-40mm armor.
Which means more money=fewer tanks.
And you still have not figured out the poor vision and poor ammo selection (6pdr offers more HE potential if you can change doctrine) or the poor aiming choice or the poor sights or the fact that unless you used the 6pdr 10cwt you don't come close the flat trajectory of the 2pdr to help with the poor sight/shoulder aiming problem. Maybe they give up on the shoulder aim when faced with an over 1000lb (480kg) gun tube?

Hopefully, starting out with a heavy gun would've been a good enough an argument that a 'proper' elevation mechanism is used.
There were CS tank vesions of the early British tanks, even the A9 had such a version, so there the 6pdr should not be a problem to install there. As for the bigger tanks = need more money, come 1939 British were making tanks between 5 tons and 26 tons. Having the 13, 18 or 26 ton tanks armed with 6 pdr changes the math very slightly wrt. the purchasing price.
Lowering of the ammo count was a thing in the historical tanks when these were being up-gunned, everyone accepted the trade-off and never looked back.

 

[Elan Vital]

And why would it be necessary, if the cartridge case of 76-mm and 85-mm is the same? Given this fact, the 85mm gun was a better solution for the T-34.

I was under the impression the S-54 used the 3-K cartridge case and the 85mm tank guns used the 52-K cartridge case, the latter being longer than the former. Is this incorrect?

tomo pauk FWIW, William Blagden of the AFV Branch would report in the immediate aftermath of the battle of France:

"All tanks and most armoured cars must have cannon. The 2 pdr is only just heavy enough. The French 47mm is more suitable. We must legislate NOW for the production of a bigger gun , which should be a weapon specially designed for tank purposes"

"All larger tanks (30 ton class) need in addition a low velocity large calibre gun to deal with anti tank defenses. We have at present nothing bigger than the 3" howitzer. The French have a 75mm gun in their Char B, and the Germans a 105mm gun on their Skoda tank (mistaken 150mm). We must not go on designing tanks that are outclassed when they are still on the drawing board. A suitable gun must be designed now, or we must manufacture the French design".

Golding in late May 1940:
"I am convinced that it will be a grave error if any Infantry tank of the future is not equipped with at least a 75mm shell firing weapon for neither slugs nor machine guns can put out of action anti-tank crews who drop into their slit trenches when things get too hot. The result that unless the anti-tank gun is over-run in actual fact, the crew pop up in time to bag the next tank whereas if half a dozen 75mm shells could be burst on the anti-tank gun position the chances are that the crew would be knocked out."

Meanwhile, all the way back to May 1939 or so, Colonel Davidson would note that the deletion of auxiliary turrets might allow the mounting of heavier armament should British tanks find themselves outgunned. As the 2pdr, with its 39mm bore, was already a smaller caliber gun than the French 47, Davidson suggested that "You may therefore be contemplating that the heavy cruisers of the future shall be armed with heavier piece such as D of A's new 6 pdr of 56mm bore". This a year or so before the order to develop 6pdr tank mountings and turrets.

At the very least, all specifications of tanks launched after the 6pdr idea was sufficiently frozen (in 1939 or a little earlier) should have included provisions for it, with new turrets for ongoing projects being designed for it at the earliest moment.

Regarding the cost/weight issue, the British were not shy about designing tanks beyond 20 tonnes from 1935/36 onwards (even ignoring Matilda II). The A16 weighed 21 tons, the A14 24 to 28 tons, and the initial A15 28 tons. The difference with other countries was that all these Medium Tank/Heavy Cruisers used that weight to increase engine bay size for bigger engines, to accomodate heavy "multiple small wheel" suspensions, and to accomodate two auxiliary MG turrets (or more!) armored at 30mm; rather than to accomodate genuinely heavy armor and/or larger guns.

I have been wanting to participate in this thread for a while but considering how interrelated tank guns and tanks themselves are, I have found the task daunting. So I am limiting myself to this snippet.

 

[bf109xxl]

Hi
The Soviet T-26 details contained on page 215 of the same source as I mentioned in Post#20 previously:
View attachment 808765

I'm afraid this source contains completely unreliable information and is not based on either archival material or service manuals. Soviet T-26s did not have such designations, no 12.7-mm machine guns were installed on serial vehicles (and even prototypes0), as well as guns of other calibers than 37 and 45 mm (except for experimental recoilless 76-mm and 76-mm on a prototype with designation T-26-4, which was not mass-produced). Moreover, most of the 37mm guns were of the Hotchkiss system, the B-3 (5K, a mutant of the Rheinmetall and PS-2) was installed on no more than 30 of the 450 twin-turreted tanks equipped with the cannon.

 

[bf109xxl]

I was under the impression the S-54 used the 3-K cartridge case and the 85mm tank guns used the 52-K cartridge case, the latter being longer than the former. Is this incorrect?

The difference was negligible. I can cite document - а report of Eduard Satel (Chief Engineer of the 1st Department of the People's Commissariat of Armaments) at the joint conference of the People's Commissariats of Armaments and Munitions held in the summer of 1943, he mentioned this factor as decisive.

 

[tomo pauk]

Captain contrary at the ready

The MK II was a sort of in-between tank. It doesn't get quite enough credit for the 20mm gun. Think of it like a modern tank/AFV with one man turret with a auto-loading gun using easily replaceable ammo cassettes
Having one man turret still sucks but having 10 shots for an auto-loading semi-auto gun beats the heck out of some of the single shot guns for repeated shots or engaging several closely grouped targets. Early German doctrine (manual) called for AP against hard targets and MG against soft target. AT gun with shield was a hard target, When flanked and being shot at from the side (crew) it was a soft target.
Granted having a two man turret with the same gun/s is even better.

Good points.

Now biting the bullet and making the chassis about .5 meters wider like they did to the Hetzer offers a lot of possibilities. don't wait until the spring of 1944.

Again good points.
Interestingly enough, Germans were planning by early 1944 to have, from winter of 1944/45, the monthly production of 3000 tanks + 'StuGs', from Pz-IV and Hetzer to the very heavy stuff. Hetzer was supposed to cover exactly 1/3rd of that number, ie. 1000 pcs monthly production by early 1945.

Neither offers any real advantage over the 5cm/L 60.

Not from the 1942 and on (installation of the long 5cm lagged perhaps a full year vs. the ATG version), but certainly in 1940 and in 1941 either of the better 47mm guns was better by the virtue of being there, and free, together with their ammo.

Waste of engineering time. Don't creep up on the more effective gun, just go for it. Germany doesn't have the engineering capacity to waste on some of the ideas it was already pursuing

The stuff suggested can be done before ww2 starts.
Skip the development of the short 5cm in order to save time, money, material and manpower resources.

Much like the above. And decide what you want the Stug-III to do. Early war it was artillery support, sit back from the battle and lob shells in. It had artillery type sights and there was at least one forward observer per platoon (in an armored 1/2 track). It could get in close for direct fire but that exposed it to direct fire.

The n.A.16 was outfitted with the increment charges, so it is still fully able to do the field artillery tasks. Having the greater oomph can help with dealing the field fortifications and houses where the enemy might be located.
Again, this also can be done before ww2.

You could even have the 8.8cm/L56 in the Spring of 1942.
Swap 88mm for the 105mm.

Yes, indeed.
Would've made for a less stressed vehicle than the Dickermax, too.

 

[Shortround6]

Hopefully, starting out with a heavy gun would've been a good enough an argument that a 'proper' elevation mechanism is used.
There were CS tank vesions of the early British tanks, even the A9 had such a version, so there the 6pdr should not be a problem to install there. As for the bigger tanks = need more money, come 1939 British were making tanks between 5 tons and 26 tons. Having the 13, 18 or 26 ton tanks armed with 6 pdr changes the math very slightly wrt. the purchasing price.
Lowering of the ammo count was a thing in the historical tanks when these were being up-gunned, everyone accepted the trade-off and never looked back.

The purchase price in 1939 or at least in late 1939 was not a problem, the problem was from 1930 to 1938/early 1939.

From Wiki so who knows, it is foot noted.
"A Covenanter tank cost the British Government £12,000, a Crusader tank cost £13,700, a Matilda tank cost £18,000, and a Valentine tank £14,900"
They had the mock up of the Covenanter ready for inspection in April of 1939.
There were also two nearly 30 ton prototypes.
The A14

about 4 tons overweight, used Thornycroft 500hp V-12.
and the A16 that looked similar but used Christie suspension and Liberty engine. Neither appears to have been fitted with armament.
Overly complex, way too many shot traps, no real increase in firepower, and so on.
Even the First Churchill showed some rather strange ideas.

Although with a large hull they stored about 150 2pdr rounds and 58 rounds (HE and smoke) for the 3in gun in the bow.
When they shifted to the 6pdr they stowed 84 rounds and when they went to the 75mm they stowed the same.

The CS tanks used very, very, very low powered guns. The 3in used a 13lb shell at around 600-700fps. It was about 30lbs lighter than the 2pdr gun.
The older 3.7in (talk about a waste of design effort) used a 15lb bomb at barely over 600fps and was about 30 lbs lighter than the 3in howitzer.
Trying to jam a 720-768lb 6pdr gun in the same space was difficult.

The 3.7in tank mortar ammo is not shown.

 

[tomo pauk]

Even the First Churchill showed some rather strange ideas.
Although with a large hull they stored about 150 2pdr rounds and 58 rounds (HE and smoke) for the 3in gun in the bow.
When they shifted to the 6pdr they stowed 84 rounds and when they went to the 75mm they stowed the s

Had they started the Churchill with the equivalent of the French 75mm gun from the Char B installed in the turret (and no hull howitzer), that would've provided the army with a capable HE thrower and a good AP performer from day 1.
Even better if a more potent gun was installed.

 

[Shortround6]

Had they started the Churchill with the equivalent of the French 75mm gun from the Char B installed in the turret (and no hull howitzer), that would've provided the army with a capable HE thrower and a good AP performer from day 1.

There is some question about the last part.

From

Char B1 Bis - Tank Encyclopedia

The Char B1 Bis was a heavy tank used by the French army in 1940, famous for strong firepower and armor, but also complexity and unreliability.

tanks-encyclopedia.com

"Two shells were standard-issue for the 75 mm ABS. The first was the Obus de rupture Mle.1910M (ENG : Rupture Shell model 1910M), which was an armored piercing high-explosive shell. The shell had a weight of 6.4 kg, and contained 90 grams of explosives. It was fired at a muzzle velocity of 220 m/s. It offered an armor penetration of 40 mm at an incidence of 30° and a range of 400 meters."
"The other shell was the Obus explosif modèle 1915 (ENG: Explosive Shell model 1915), a high-explosive shell. It weighed 5.55 kg, and contained 740 grams of explosive. It was fired at a muzzle velocity of 220 m/s."

Even better if a more potent gun was installed.

The British did install a more potent armor piecing gun, it was called the 2pdr

The 790m/s velocity made it much easier to hit with too. Nearly 2 seconds for the time of flight to 400 meters?
This was not a French 75 field gun with a sawed off barrel. In Pistol terms this was taking a .357 magnum and not only cutting the barrel down from 200mm to 100mm but cutting the cartridge case back the length of the .38 Smith & Wesson (also known as the .380 Webley) and leaving over 1/2 the powder out.

 

[tomo pauk]

From

Char B1 Bis - Tank Encyclopedia

The Char B1 Bis was a heavy tank used by the French army in 1940, famous for strong firepower and armor, but also complexity and unreliability.

tanks-encyclopedia.com

"Two shells were standard-issue for the 75 mm ABS. The first was the Obus de rupture Mle.1910M (ENG : Rupture Shell model 1910M), which was an armored piercing high-explosive shell. The shell had a weight of 6.4 kg, and contained 90 grams of explosives. It was fired at a muzzle velocity of 220 m/s. It offered an armor penetration of 40 mm at an incidence of 30° and a range of 400 meters."
"The other shell was the Obus explosif modèle 1915 (ENG: Explosive Shell model 1915), a high-explosive shell. It weighed 5.55 kg, and contained 740 grams of explosive. It was fired at a muzzle velocity of 220 m/s."

The 220 m/s MV figure is bogus in that article. See here (can be translated): link
470 m/s for the APHE.

The British did install a more potent armor piecing gun, it was called the 2pdr

The 790m/s velocity made it much easier to hit with too. Nearly 2 seconds for the time of flight to 400 meters?
This was not a French 75 field gun with a sawed off barrel. In Pistol terms this was taking a .357 magnum and not only cutting the barrel down from 200mm to 100mm but cutting the cartridge case back the length of the .38 Smith & Wesson (also known as the .380 Webley) and leaving over 1/2 the powder out.

Both the French short 75mm and the British 2pdr will have no problems to deal with German tanks of 1940. Both of them will still be able to deal with them in 1941 unless the head-on shot is required beyond 500m. Assumes no advance in shot/shell technology.

 

[Shortround6]

The 220 m/s MV figure is bogus in that article. See here (can be translated): link
470 m/s for the APHE.

Thank you for the correction and for the link.

Both the French short 75mm and the British 2pdr will have no problems to deal with German tanks of 1940. Both of them will still be able to deal with them in 1941 unless the head-on shot is required beyond 500m. Assumes no advance in shot/shell technology.

Here is where the British really fell down.
So far I have not found when they introduced the HV shot (normal uncapped shot with more powder).
The APCBC doesn't show up at all until late 1942 and mass production in 1943 which is way too late and almost overlaps the squeeze bore shot.
And as I have said, the APCBC technology dates to WW I.

What I have never seen is the explanation as to why the towed AT guns could not have HE rounds (they were part of the Royal Artillery) and why the tank guns could not have HE rounds and the explanation that only the artillery could fire HE rounds doesn't hold water as the old Vickers Mediums from the 1920s had a few 3.7in mortars and the A9 and A 10 certainly did.
The later CS tanks with 3in howitzers certainly had HE rounds and yet the 2pdrs in tanks parked a few dozen feet away in the same units cannot have HE ammo?
Something smells.

 

[tomo pauk]

Thank you for the correction and for the link.

No problemo

Here is where the British really fell down.
So far I have not found when they introduced the HV shot (normal uncapped shot with more powder).
The APCBC doesn't show up at all until late 1942 and mass production in 1943 which is way too late and almost overlaps the squeeze bore shot.
And as I have said, the APCBC technology dates to WW I.
What I have never seen is the explanation as to why the towed AT guns could not have HE rounds (they were part of the Royal Artillery) and why the tank guns could not have HE rounds and the explanation that only the artillery could fire HE rounds doesn't hold water as the old Vickers Mediums from the 1920s had a few 3.7in mortars and the A9 and A 10 certainly did.
The later CS tanks with 3in howitzers certainly had HE rounds and yet the 2pdrs in tanks parked a few dozen feet away in the same units cannot have HE ammo?
Something smells.

Unfortunately, we are unlikely to ever know the answers to all these whys.
Both French and British tanks are worthy of their equivalent of the 'Secret horsepower race' book, where a dedicated researcher will invest his time, effort and money to sift through the files of the War Ministries and Army commands in order to unearth the real stuff. Some of the whys for the British tanks were covered in the book 'The great tank scandal' by David Fletcher, but it ought to be much more to read, and with good footnotes.

 

[Elan Vital]

Unfortunately, we are unlikely to ever know the answers to all these whys.
Both French and British tanks are worthy of their equivalent of the 'Secret horsepower race' book, where a dedicated researcher will invest his time, effort and money to sift through the files of the War Ministries and Army commands in order to unearth the real stuff. Some of the whys for the British tanks were covered in the book 'The great tank scandal' by David Fletcher, but it ought to be much more to read, and with good footnotes.

P.M. Knight sorta is doing that with his "A Technical History" series on British wartime tanks (going as early as A13 so far with references as early as A6). Although re 2pdr HE, he has yet to find the exact quotes which would unearth the truth. What transpires for his work so far is that British officers of the relevant departments thought machineguns sufficed against infantry and AT guns.

For French stuff, well we still are stuck with the works of defunct Stéphane Ferrard and Pierre Tauzin and still living Pascal Danjou and François Vauvillier (GBM magazine), with the limitation that most of their work doesn't always tell the exact archive references or cite exact paragraphs to confirm hypotheses. Though I think part of it is because they hadn't stumbled on the exact justifications yet.

 

[Frog]

This is where the Valentine shines, and even more a 'proper' 18-20 ton tank. Making more of them instead of the light tanks is/was a way to go. Unfortunately for the historical British tanks arm, Valentine was too late for the pre-1940 build-up.




Use the 6pdrs with normal barrel lengths in the 1920s - these were good for 538 m/s as-is, ie. no worse than the field guns of the day - and see that can be done to improve the AP performance.
Move to the higher-power 6pdrs or/and 12-13 prd guns by the mid-1930s.



I want quality, so the original length 6pdr is simply great.
BTW - the 2 pdr scores zero points for the HE ability, same for the 3pdr. Even if we stick the HE shells on these guns, one 6 pdr shell is worth perhaps as much as three 2 pdr shells, or as much as two 3 pdr shells; I'm being conservative on purpose here. A tank that the 6pdr hits will be most likely destroyed, together with it's crew (sorry, folks), while the 2 pdr will require a few additional hits to do the same.
We also have a thing that British have all of the 1930s to start designing and debugging the tanks with the better abilities if they start with the 6 pdr, that also makes the path to the further upgrades of firepower easy job.


We do not.
French were moving from 37mm to 47mm (so it is a step up), and their 47mm guns were issued with HE shells. French were also installing the most powerful 75mm guns on the tanks of 1930s, whose purpose was both for AP and HE. It will take until 1941 for someone to beat them in that game; it will take the British until 1943 to beat the French in the installation of a 75mm gun on a tank.
Both Soviets and Germans were issuing the 75-76mm guns on the tanks in the late 1930s (Soviets even earlier), and their small guns on the tanks were still with the HE shells. Germans were making the StuG-IIIs with the 75mm gun; yes, it was not a tank.

Nobody else was saying: okay, now that we have a 20-30 ton tank, putting the very small gun on it is the greatest idea.

The Churchill Mk I of Dieppe fame had a hull mounted Ordnance QF 3-inch howitzer (76 mm) in 1942.