British 1936-42 purchase options, logistics and export/import of military hardware (1 Viewer)

[tomo pauk]

And the French souped-up 47mm tank gun still wasn't as good as the British 40mm.
Some of the proposed 6pdr/57mm tank guns aren't much better than the British 40mm and weigh more, need larger/heavier turret, and restrict ammo capacity.

Role of a tank gun is not the same as the role of an AT gun.
The ww1-vintage 6pdr was far better than the 2pdr when we talk about the HE performance. The 6pdr can be also a passable smoke thrower - even if only to mark the target(s), and can also put the beehive ammo to a good use - the categories where a 40mm is very weak.
Using several shots to do what one bigger piece of ammo does is a false economy.

For some reason everybody thinks the standard British 6pdr was a bad gun. It was being designed in 1938, it was test fired in 1939. It should have gone into production in late 1940 or early 1941 and most British service tanks in 1942 should have had the 6pdr in late winter/early Spring of 1942, not just showing up in the late fall of 1942.

Nobody says that the standard 6pdr was a bad gun. What was bad was the timing, that gotten worse due to the invasion panic. Bad timing is the greatest shortcoming a weapon can have (apart from some weapons having an 'intent' to kill the opeartor(s), like the Me 163).
Army, fro example, picking up the Navy's 1930s 6pdr saves them years, and Army can have that gun in use before they start to disembark their units in France.

As far as the 2pdr goes. I may be being a bit of stickler here. The Standard 2pdr tank/AT gun was semi-auto. This may be a translation issue.

These were the QF weapons. I've suggested a true semi-auto gun.

Cheapest, easiest solution for British tank guns was to use the 2pdr, Fit either 40mm Bofors shells or 2pdr Pom-Pom shells for HE, design and build APCBC ammo and issue it by the beginning of 1941.

Cheapest and easiest solution don't need to happen with a bit of foresight. With that foresight, and within the confines of this thread, the 2pdr would've remained just a footnote, and British would've been using much more potent guns by late 1939, all while taking into account the state of war budget and state of industry.

 

[Elan Vital]

Well the Matilda was kind of a special case. It was small (volume) for it's weight. It was a bit easier (not a lot easier) to transport than a larger tank of the same weight. Still needs the same bridging equipment. The Matilda only gained it's reputation because of it's armor for the most part. It carried a bit less ammo than the Cruiser tanks. You also need a bigger hull to fit in a bigger powerplant if you want a faster tank and the increased hull size is going to run up weight quick.

On Matilda II, the powerplant was not very volume and weight efficient because of the twinned up engines and the transfer case to combine the outputs. I'm not sure if the Soviet figures are actually true, but you could actually fit the Churchill's Bedford engine in a smaller volume than the twinned up Matilda setup, and even the former is not all that efficient so there is even greater room to improve.

Spoiler: Engine specs:

Keep the 2pdr, Keep the basic A 13. work on fixing the existing Liberty and not start dissipating design and development work on 3 different bespoke tank engines, while trying to sort out the modified Liberty.
For the A 13, add more armor, add 5 wheel if needed.

Get the Centaur/Cromwell into production sooner. Maybe by killing the Covenanter on the drawing board. And perhaps a few other projects.

Just get the tank guys and the gun guys to talk to each other sooner. A close to Comet with the 77mm in production at the end of 1943?
Put a sloped nose on it instead of the left over Cromwell nose.

Considering that Covenanter and Crusader only existed to squeeze a Light and a Heavy Cruiser into a 18 ton weight limit, you could get away with indeed just improving the A13 Mk II somewhat while working on the 1938/39 A13/A15 within a 25 ton limit (or at least slightly in excess of 20 tonnes), ideally accounting for the incoming 6 pdr and a proper new engine.

Especially when they use single skin construction and a slightly higher weight budget (greater than Crusader Mk III), you can absolutely obtain Cruisers with the same frontal protection as a Valentine but without the drawbacks. In general with a slightly higher weight limit and better design you could absolutely run the Cruisers with balanced protection, moblity and firepower in 1940 already.
The curse of the British Cruisers was that they kept only increasing design weights (and design load capacity for the springs) incrementally instead of leaping to new weight categories in one go. 13-14 tons with A13, 16 tons with Covenanter, 18-19 tons with Crusader and Covenanter III, 21-25 tonnes with Cavalier and early A27, 28-30 tonnes with late A27, A28, and Heavy Cromwell Stage I, 32-35 tonnes with the A31, A32, A35 and Heavy Cromwell Stage II, and up to and beyond 40 tons with A36, A37 and A40.

Ideally, one could do with A13, 1940 generation Cruiser (25 ton limit chronological stand-in for Crusader/Covenanter), 30-ton (or more) Cruiser (A27 or ideally something closer to A34 Comet from the start, A30), 35-40-or 45 ton Cruiser (A37/Centurion stand in). Ideally going for a significant weight increase with A27/34 stand in would allow the immediate use of the armor schemes developped for Heavy Cromwell Stage I, A28-31-32, eg 3.5, 4 or 4.5 inches.

Of note that A37 and other late projects used a special external variant of Christie suspension which allows single-skin sides, and the mount for that suspension was stronger to handle the heavier weight. Another remark is that most Christie suspension setups require cross tubes on the bottom of the hull which take a similar space as torsion bar suspension. You could actually get away with using TB suspension on British and other Christie tanks with next to no height penalty, but a sizeable gain in space and available width no longer taken by the springs. And some weight savings. Incidentally the French AMX-40 did use external Christie suspension.

Cross tubes seen here on the floor of this A30 Avenger.

External Christie on the AMX-40 sitting between the hull and the roadwheel and side skirts, efficiently fitting over the wheel support which already requires width.

And the French souped-up 47mm tank gun still wasn't as good as the British 40mm.

Yes, at least once APC(BC) was introduced on 2pdr. (Also tomo pauk ) The 590 m/s MV would refer to the HE round on 47 SA 35, the real comparison would be between 47 SA 34 and 47 SA 35 which shot the antitank projectile at 450 and 660-680 m/s respectively.

For some reason everybody thinks the standard British 6pdr was a bad gun. It was being designed in 1938, it was test fired in 1939. It should have gone into production in late 1940 or early 1941 and most British service tanks in 1942 should have had the 6pdr in late winter/early Spring of 1942, not just showing up in the late fall of 1942.

It was definitely the best sub-75mm gun of WW2. Ironically, the British were the 2nd country after France to actually field heavily armored tanks (A11 and A12), with the USSR not far behind. If an underfunded British tank program could do this, then the British should have accounted for the enemy being able to field at least equally armored tanks, requiring appropriate ammunition for the 2 pdr and ideally a more powerful gun even if only as part of a 2-tier system (just like France with 25 and HV 47mm).

Again as an analogy to the French, the latter tested 25, 37 and 47mm projectiles (capped, with or without BC) against 20, 40, 47 (sloped), 50, 60, 75, 80, 90 and 100mm cemented or homogenous plates just in the year of 1936. Since 1934 already they were looking at engaging thick (T/D of 1 or greater), sometimes cemented plates which is why they exclusively used solid shot APC(BC) on all new guns below 75mm caliber (here they worked on capped APHE). Difficult targets will often break up the solid shot projectile anyway which makes a bursting charge less relevant.

Many countries instead expected just the bulletproof or 30mm-thick-or-less armor schemes of the 1930s and 1940 and used APHE, often without an AP cap. But due to the bolded bit above, there should have been good reason to start developping 2pdr ammo of similar construction to the French projectiles from 1934 onwards when A11 was mooted. Had the Director of Artillery been allocated the ressources needed to proceed with 6pdr at a less constrained pace and schedule, it could have been in production in 1940 already with both the towed carriage and tank mount and turret figured out. This would be enough.
As you noted, HE should also be available for 2 and 6pdr from the start regardless of their value, both are already a little better off than respectively 37 and 47/50mm calibers in terms of possible payloads. Additionally, early development of APCBC and HE (almost from the start) would also allow tanks to be designed accordingly around longer ammo than the plain AP and no HE that the guns started with. Historically this created issues with ammo stowage when new ammo types were introduced.

Same issue with 17 pdr historically as well (no APC and APCBC at the start) which created issues for the A30 Challenger which was well in development before the ammo types were devised.

Please note that the French 75 was NOT semi-automatic even though it was "quick firing" weapon. It depended on a gunner's hand to operated the handle to open and close the Breech. US/British tank cannon could fire French 75mm ammo but the tank guns had new breech blocks (they also had new barrels).

Of note that the French 75mm tank guns with mle.97 ballistics (the aptly-named 75mm "Self-Propelled Type") were derived from the mle.1929 casemate gun with a new barrel and a new sliding breech. Automatic at that, eg the breech closed automatically when the round was rammed in by the spring-operated mechanized rammer to reduce the loader's work .

 

[z42]

Some of the proposed 6pdr/57mm tank guns aren't much better than the British 40mm and weigh more, need larger/heavier turret, and restrict ammo capacity.

Great, ditch the medium velocity 6pdr. Keep the 2pdr,

I'd expect that a MV 57mm gun would have about similar AP performance as the historical 2pdr. Which ought to be good enough for the first couple of years of the war. The upside would be having a much better HE shell. Maybe smoke too. Similar to the logic that led to the QF 75mm being preferred as a tank gun to the 6pdr.

I want to avoid having to have a separate tank for shooting HE or smoke. But if 75mm is really considered the minimum for useful HE or smoke shells, then I suppose there's no way around it that we need separate AP and HE tanks, and in that case one may as well go for the 2pdr, which seems to have been a perfectly fine gun for shooting at tanks early in the war. Even so, use the same tank and turret for the AP , just mount a different gun. Some kind of low(ish) velocity 75mm for the HE tank?

At the minimum, at least give HE and APCBC shells for the 2pdr.

Just get the tank guys and the gun guys to talk to each other sooner. A close to Comet with the 77mm in production at the end of 1943?

I'd argue for going straight away for a tank big enough to carry the full 17pdr, obviating the need for the 77mm HV gun altogether.

Granted this is a what if but the solution seems to be to take old, crappy 6pder guns and/or ammo ( or build new guns to old dimensions), design and build new HE shells, and then design/build new AP projectiles, some of which will be some sort of APCR shot (tungsten steel core?) to get around the fact that the old 6pdr guns/ammo aren't any better than the 2pdr gun using cheap solid one piece projectiles.

I recall it has been discussed in this forum that the steel core APCR's got about equal penetration to classic APCBC shells. Just go with whatever is cheaper? APCR doesn't need any HE filling nor a fuse, OTOH it needs the aluminum(?) sleeve which might be in high demand by the aircraft industry? Or just go with a full-bore solid steel APC(BC) (use less powder for the HE shell to roughly match trajectories?)?

 

[Shortround6]

I'd expect that a MV 57mm gun would have about similar AP performance as the historical 2pdr. Which ought to be good enough for the first couple of years of the war. The upside would be having a much better HE shell. Maybe smoke too. Similar to the logic that led to the QF 75mm being preferred as a tank gun to the 6pdr.

The 2pdr, and every other 37-57mm gun had a poor HE payload. But every other nation adopted and issued HE rounds. Poor does not mean useless. The French had literally thousand of tanks running around with the short 37mm guns that had 30g of HE in WW I and during the 1920s and early 30s. They adopted a Mle 1936 shell that held 56g and the longer barreled 37mm SA 38 gun used a shell with 60 grams.
British tankers in NA were using the 2in smoke mortar (same bombs as the 2in mortar) for some sort of HE capability at very close ranges to try to get around the High Commands stupidity.
From a design view point a shell of a certain velocity needs shell walls of a certain thickness to withstand the stress of firing, assuming equal strength steel. SO just picking numbers out of a hat, if you need 10mm shell walls your 37-40mm shells have a space 17-20mm in diameter to house the HE in. The 57mm has a space 37mm in diameter and the 75 has a space 55mm in diameter. If you want to use a few more mm of wall thickness go ahead on the big shell. But shells are often longer as they get bigger in diameter and cube law shows up. A 75mm will hold 3-4 times the explosive of a 57mm. The 57mm can hold 3-4 times the explosive of a 37mm.
Smoke came in two varieties, a white phosphorous type (or similar) that burned hot and the smoke, being hot, formed in columns or pillars. The other type used cannisters (varied in number) of smoke compound that were ejected out the base of the shell. These tended to produce 'smoke' that was cool and either hugged the ground or at least didn't rise quickly.
For tank use in 75mm guns it mostly the WP type. The shells were simpler, fusing was simpler. Unfortunately you need a lot of WP to get a decent smoke screen, a couple of 15-20ft wide columns rising hundreds of feet does not hide tanks very well. And a small shell also means the column is thin.
The British and Americans both used the 2in bomb thrower but that was more for hiding the tank itself from incoming fire rather than screening the AT positions and allowing the tanks to advance behind the smoke screen.

I'd argue for going straight away for a tank big enough to carry the full 17pdr, obviating the need for the 77mm HV gun altogether.

The 17pdr was big gun, and it used big ammo and it had a lot recoil. The 77mm used the same projectiles. The 77mm had about 10% more penetration than the US 76mm tank gun and that is with standard projectiles.
We in 2025 know when the new tanks showed up. The 77mm British gun could penetrate about 20% more than the long 75mm gun in the German MK IV.
Unless you use a big turret for the 17pdr you have a slow rate of fire. With the Comet the British get good compromise. A fast, well armed tank.
The Centurion was a heck of a tank, but it had the speed of of Tiger I and short road range. It was a good defensive tank. British had swung to gun power but it did cost them.

I recall it has been discussed in this forum that the steel core APCR's got about equal penetration to classic APCBC shells. Just go with whatever is cheaper? APCR doesn't need any HE filling nor a fuse, OTOH it needs the aluminum(?) sleeve which might be in high demand by the aircraft industry? Or just go with a full-bore solid steel APC(BC) (use less powder for the HE shell to roughly match trajectories?)?

If you want APCR to work you have to make the multi piece ammo very carefully. More labor. Make it sloppy and it still will penetrate..............if it hits. Poor accuracy is going to hurt.

 

[Shortround6]

I will note that the British took a while to decide if the vehicle 17pdr needed two loaders or only one.
Challenger...........2 loaders.
Avenger................1 loader with a 2nd one optional
Archer....................1 loader
Achillies..................2 loaders
Firefly.....................1 loader
Centurian..............1 loader

A lot may depend on rate of fire desired and the access to ammunition or lack thereof.
A 2nd loader, cramped as that may be, may speed up the rate of fire by passing ammunition from ammo bins that the primary loader cannot easily reach.

 

[tomo pauk]

The 2pdr, and every other 37-57mm gun had a poor HE payload.

That is quite a wide brush, lumping the 37 and 57mm guns in the same basket wrt. the HE payload. A 57mm HE shell can indeed have 3-4 times the He filling - like 245g for the Soviet 57mm. The 57mm shell will be also flinging a much more lethal 'rain' of shrapnel, talk 2.5-3 heavier mass of steel. A light field cover, like a small tree or an immobilized truck or halftrack, will be less of an useful cover for the enemy infantry. A 57mm shell that landed in a room through a window will annihilat the enemy infantry there.

Similar is with the enemy tanks - a tank that is punctured by a small AP shot might still have both the tank and the crew being able to fight very soon, while a 57mm shot that penetrated will make a greater mess of the tank's internals, including the crew. Especially if the shot is of the APHE variety.

The 17pdr was big gun, and it used big ammo and it had a lot recoil. The 77mm used the same projectiles. The 77mm had about 10% more penetration than the US 76mm tank gun and that is with standard projectiles.
We in 2025 know when the new tanks showed up. The 77mm British gun could penetrate about 20% more than the long 75mm gun in the German MK IV.
Unless you use a big turret for the 17pdr you have a slow rate of fire. With the Comet the British get good compromise. A fast, well armed tank.
The Centurion was a heck of a tank, but it had the speed of of Tiger I and short road range. It was a good defensive tank. British had swung to gun power but it did cost them.

These were the main reasoning I've suggested that the equivalent of the 77mm HV is made 1st, followed with a more powerful gun.

If you want APCR to work you have to make the multi piece ammo very carefully. More labor. Make it sloppy and it still will penetrate..............if it hits. Poor accuracy is going to hurt.

Then start it out ASAP. There is no guarantee that the Gen 1 will be great, so use the lessons learned during the tests for the Gen 2.

 

[z42]

The 17pdr was big gun, and it used big ammo and it had a lot recoil. The 77mm used the same projectiles. The 77mm had about 10% more penetration than the US 76mm tank gun and that is with standard projectiles.
We in 2025 know when the new tanks showed up. The 77mm British gun could penetrate about 20% more than the long 75mm gun in the German MK IV.

The British met the Tiger I in combat apparently in (very) late 1942 (and probably they had some information from spies beforehand that the Germans were going to introduce a new very heavy tank into service?). For a late war tank introduced, say, mid 1944 that's still one and a half year. And even if the specs have to be nailed down before late 1942, it doesn't take a genius to look at a plot of tank weight vs year of introduction and conclude that tanks are gonna get heavier, thus requiring ever heavier guns to punch through their armor.

FWIW, the 17pdr was quite close to the German 75 KwK 42 used on the Panther. Seems to have worked well enough there? In fact, the shell case is even slightly shorter for the 17pdr, 583 vs 640mm, though at least by a quick visual look the case looks fatter.

 

[Shortround6]

In reverse

Then start it out ASAP. There is no guarantee that the Gen 1 will be great, so use the lessons learned during the tests for the Gen 2.

The British were late to the party with APCR shot. They seemed to do a good job with the 2pdr but since that was supposed to fired out of squeeze bore adaptor perhaps they took a bit more care? They didn't issue a lot of 6pdr APCR shot so reports are rare. They got the APDS into service soon after and that took over and by all accounts it worked well.
Problem came with the 17pdr APDS and reports are all over the place, some reports say there was only one bad batch, others say that while accuracy varied none of it was as good as the standard solid shot. You would think that after a couple of tries they would have it worked out. Strangely the 77mm using the same projectiles never seemed to have the problems the 17pdr had. One source says the 17pdr was still having problems in Korea. 6-7 year old ammo or they never got it sorted out? Sabots going through the muzzle brake?

These were the main reasoning I've suggested that the equivalent of the 77mm HV is made 1st, followed with a more powerful gun.

I am in full agreement here. Having the gun makers and the tank makers talk to each other would have been a huge advantage.

That is quite a wide brush, lumping the 37 and 57mm guns in the same basket wrt. the HE payload. A 57mm HE shell can indeed have 3-4 times the He filling - like 245g for the Soviet 57mm. The 57mm shell will be also flinging a much more lethal 'rain' of shrapnel, talk 2.5-3 heavier mass of steel. A light field cover, like a small tree or an immobilized truck or halftrack, will be less of an useful cover for the enemy infantry. A 57mm shell that landed in a room through a window will annihilat the enemy infantry there.

Similar is with the enemy tanks - a tank that is punctured by a small AP shot might still have both the tank and the crew being able to fight very soon, while a 57mm shot that penetrated will make a greater mess of the tank's internals, including the crew. Especially if the shot is of the APHE variety.

Yes the 6pdr would be better for HE, but the 75mm guns could usually fire smoke, which the 6pdr never did.

So we are trading a much heavier, larger gun that won't do much better at armor punching for an HE shell that is around 1/3 as powerful as the 75mm low velocity.
Depending on the size of the tank we accept a lot of other negative points. If we go for a 20-24 ton tank we can overcome many of them.
Goals for the 6pdr armed tank should be a 3 man turret with enough room to really work the gun (high rate of fire) and better vision than any British tank until the Comet. British had room, they went from slightly better than the French to very good in one jump. Plenty of room for some intermediate steps.
Keep well over 3000 rounds of MG ammo. Do not trade MG ammo for main gun rounds unless they keep the suggested minimum.

At one point in NA the Crusaders were running around with 10 2in mortar bombs of HE and 20 of smoke for the "official" load out. Some Valentines did the same thing.
Many crews begged/borrowed/stole extra HE bombs and also got longer ranged propelling charges. Just issuing 2pdr HE ammo would have given the tankers roughly as good HE that ranged hundreds of yards further.

 

[Shortround6]

The British met the Tiger I in combat apparently in (very) late 1942 (and probably they had some information from spies beforehand that the Germans were going to introduce a new very heavy tank into service?). For a late war tank introduced, say, mid 1944 that's still one and a half year. And even if the specs have to be nailed down before late 1942, it doesn't take a genius to look at a plot of tank weight vs year of introduction and conclude that tanks are gonna get heavier, thus requiring ever heavier guns to punch through their armor.

FWIW, the 17pdr was quite close to the German 75 KwK 42 used on the Panther. Seems to have worked well enough there? In fact, the shell case is even slightly shorter for the 17pdr, 583 vs 640mm, though at least by a quick visual look the case looks fatter.

Turns out that many nations were not using critical thinking. They projected the larger tanks but only the Tiger II really appeared and it was not a big success. The Germans went for some very large AT guns. British were working on the 32pdr (3.7in AA gin barrel) Americans were working on at least one 105mm.
Trouble was that these big guns required a big truck/tractor to move (US towed 105mm weighed 16,000lbs) and on the other side, trying to move 75+ ton vehicles required a lot more work on engines and transmissions to make them practical.

The Panther worked. But it was near the limit for a 1944-45 tank. They made bigger tanks but the rates of fire/rate of engagement fell off. The big tanks were slow, they had mechanical problems and problems with terrain. Granted this is with hindsight.

If the British had gotten their act together (this is a what if) perhaps they could have gone ashore on DD day with 3-400 Comets and build another 100-200 a month. Granted they are not going to take out Tiger IIs from the front but the Germans didn't have that many Tiger IIs. The Comet was faster and bit lower than a Sherman.

 

[EwenS]

There is a whole thread on the WW2talk site discussing the accuracy / inaccuracy of the 17pdr with APDS ammunition, with plenty of references to original documents. The results were all over the place but that seems to have resulted from a whole variety of issues not just one. For example:-

1. Which vehicle they were mounted on, or not.
2. Barrel wear. APDS increased this. And also barrel droop which became an issue over time.
3. At least early APDS was leaving deposits in the barrels.
4. Which APDS version was used (seemingly 3 in issue in WW2). Trial batches were available for test in Aug 1944 (These were used in the Normandy trials) followed by more general issue from late Sept / Oct 1944. But it was only issued in small quantities.
5. Skill of the gunners involved
Etc, etc.

17 pounder APDS - & 17 pdr in general.

Extracts from a US report: U.S. Army Firing Test No.3 U.S. Army Firing Tests conducted August 1944 by 12th U.S. Army Group at Isigny, France....

ww2talk.com

 

[z42]

Turns out that many nations were not using critical thinking. They projected the larger tanks but only the Tiger II really appeared and it was not a big success. The Germans went for some very large AT guns. British were working on the 32pdr (3.7in AA gin barrel) Americans were working on at least one 105mm.
Trouble was that these big guns required a big truck/tractor to move (US towed 105mm weighed 16,000lbs) and on the other side, trying to move 75+ ton vehicles required a lot more work on engines and transmissions to make them practical.

The Panther worked. But it was near the limit for a 1944-45 tank. They made bigger tanks but the rates of fire/rate of engagement fell off. The big tanks were slow, they had mechanical problems and problems with terrain. Granted this is with hindsight.

If the British had gotten their act together (this is a what if) perhaps they could have gone ashore on DD day with 3-400 Comets and build another 100-200 a month. Granted they are not going to take out Tiger IIs from the front but the Germans didn't have that many Tiger IIs. The Comet was faster and bit lower than a Sherman.

Luckily for the Allies the German late war heavy tanks / TD's suffered from reliability issues, and they were never able to produce any of them in particularly large numbers. OTOH, counting on the enemy to screw things up might not be a sound procurement strategy.

As for even bigger guns, yeah, I have a hard time seeing the motivation for the German 12.8cm AT gun, except to have develop it as a hedge in case the Russians turn up with some new superheavy tank. For what was actually encountered in WWII, even the 88L71 on the Tiger II & JagdPanther was bordering on overkill.

And yes, if you want something Comet-like (~35 tons) in time for D-day, yes I agree the 77mm HV might have been a better choice than the 17pdr. Just put sloped armor on the front of the hull (losing the bow gunner in the process) and turret. And maybe use the Horstmann style suspension that the Centurion used in order to give more space inside the hull (and/or make the hull narrower).

For a Centurion-sized tank, the full 17pdr makes sense. Heck the Centurion had enough space allowing it to be upgraded with the 20pdr and the 105mm later in its career.

 

[yulzari]

For a Centurion-sized tank, the full 17pdr makes sense. Heck the Centurion had enough space allowing it to be upgraded with the 20pdr and the 105mm later in its career.

FWIW the Cromwell was upgraded from QF75mm to 20 Pounder and one trialled successfully with the L7 105mm, as the Charioteer, serving in Austria, Finland and Lebanon (via Jordan) until the 1970s. The Finns had a plan to upgrade from 20 Pounder to L7 too but it did not come to pass. The Austrians used the turrets when the vehicles were retired and mounted them as bunkers.

 

[EwenS]

The British met the Tiger I in combat apparently in (very) late 1942 (and probably they had some information from spies beforehand that the Germans were going to introduce a new very heavy tank into service?). For a late war tank introduced, say, mid 1944 that's still one and a half year. And even if the specs have to be nailed down before late 1942, it doesn't take a genius to look at a plot of tank weight vs year of introduction and conclude that tanks are gonna get heavier, thus requiring ever heavier guns to punch through their armor.

FWIW, the 17pdr was quite close to the German 75 KwK 42 used on the Panther. Seems to have worked well enough there? In fact, the shell case is even slightly shorter for the 17pdr, 583 vs 640mm, though at least by a quick visual look the case looks fatter.

The Tiger I first entered combat on the Eastern Front near Leningrad on 29th Aug 1942.

The first 3 Tiger I didn't arrive at Bizerta, Tunisia until 23rd Nov 1942 with the last of that unit's 20 Tiger I not arriving until 24th Jan 1943 (Panzer Abteilung 501). Those first 3 Tigers went into action against US Army units on 1 Dec 1942. At least 9 were lost in Jan/Feb 1943. Between 12 March and 16 April 1943, another 11 from Panzer Abteilung 504 arrived. Both units surrendered on 12 May 1943, with their surviving tanks.

It was Jan 1943 before British units encountered the Tiger, destroying one with a 6pdr on 20th Jan.

8th Army deployed its first 17/25pdr "Pheasant" guns in Feb 1943. "Pheasant" being the code name for the 17pdr gun mounted on the 25pdr carriage. Development of the 17pdr had begun in late 1940. Development problems lay in the design of the carriage, hence the "Pheasant".

A 'Pheasant' 17-pounder field gun, Sicily, 1943 | Online Collection | National Army Museum, London

collection.nam.ac.uk

 

[EwenS]

FWIW the Cromwell was upgraded from QF75mm to 20 Pounder and one trialled successfully with the L7 105mm, as the Charioteer, serving in Finland and Lebanon (via Jordan) until the 1970s. The Finns had a plan to upgrade from 20 Pounder to L7 too but it did not come to pass.

And the sacrifice to cope with the extra weight of the 20pdr gun was that the new bulkier turret only had 20-30mm of armour and accommodated only 2 crew (with only a driver in the hull). And ammunition was limited to just 25 rounds. David Fletcher of the Tank Museum described it as the fifth worst British tank produced. Some have described It as a throwback to the WW2 tank destroyer concept.

 

[yulzari]

And the sacrifice to cope with the extra weight of the 20pdr gun was that the new bulkier turret only had 20-30mm of armour and accommodated only 2 crew (with only a driver in the hull). And ammunition was limited to just 25 rounds. David Fletcher of the Tank Museum described it as the fifth worst British tank produced. Some have described It as a throwback to the WW2 tank destroyer concept.

The turret was only intended to be shrapnel proof against artillery splinters and small arms fire. The clue in the role is the official name: FV4101 Cromwell Heavy AT Gun originally. A turreted SP AT gun. Unlike a tank it is intended to be used from a hidden protected position where possible. This permits the commander to leave the vehicle and carry a line to a position where he can see the targets even when his own gun blast may obscure direct vision from the vehicle itself and advise the gunner of corrections to reset the aim before the air clears. This is an advantage not a work around. Of course this exposes the squidgy commander to small arms and shrapnel but does give him a superior situational awareness. Used by the Territorial Army through the 1950s until the BAT series of infantry AT guns, and later missiles, took on the AT role with 120mm HESH fire.

 

[Shortround6]

As detailed by others the Problem with the Charioteer is that just because a vehicle has a large gun in a rotating turret and has a roof on the turret, that doesn't make it a tank.

the Charioteer had 30mm armor on the front of the turret. It had a two man turret crew, the elevation range was from -5 to +10 degrees. The Centurion was from -10 to +20 degrees.
At some point the crew was changed to 4 men. However, as noted above the 'commander/gunner' dismounted from the turret and the 4th man, who rode in the old hull gunner position then moved into the turret and took over the gunner duties.

A lot may depend on the doctrine of the time. A lot of armies were happy with tanks with 1 or 2 man turrets because they were cheap to buy. In combat they got expensive because you needed more of them to actual perform like tanks. Like move forward into enemy territory or take part in mobile/fluid battle and take out the enemy without getting killed while doing that.

 

[tomo pauk]

Problem came with the 17pdr APDS and reports are all over the place, some reports say there was only one bad batch, others say that while accuracy varied none of it was as good as the standard solid shot. You would think that after a couple of tries they would have it worked out. Strangely the 77mm using the same projectiles never seemed to have the problems the 17pdr had. One source says the 17pdr was still having problems in Korea. 6-7 year old ammo or they never got it sorted out? Sabots going through the muzzle brake?

All the more reasons to go with APCR 1st and ASAP, and then with APDS.

Yes the 6pdr would be better for HE, but the 75mm guns could usually fire smoke, which the 6pdr never did.

So we are trading a much heavier, larger gun that won't do much better at armor punching for an HE shell that is around 1/3 as powerful as the 75mm low velocity.
Depending on the size of the tank we accept a lot of other negative points. If we go for a 20-24 ton tank we can overcome many of them.

Definitely focus on tanks heavier than 24 tons.
Note that, in my book, a 6 pdr on the tanks is the plan B. The main plan is the equivalent of the French 75mm (~12 lb kg projectile at ~600 m/s), or at least the equivalent of the short 75 mm from the Char B (~12 lb AP projectile at 470 m/s).
A decent 6pdr (talk the 1930s RN's gun, or the souped-up - 600 m/s AP? - ww1 6pdr) will still be of the greater worth in combat than the 2pdr.

 

[WARSPITER]

For the 17lber load in tanks the APDS ammo level was usually only around 6%. The main round used was APCBC.
APDS rounds weren't available in numbers until the end of June 1944.

The upgraded 75mm gun was answer to the HE problem by using a longer barrel and larger load cartridge which allowed
standard 75mm ammo to be used with far better armour penetration. This allowed the use of decent 75mm HE as well
but the different mounting and breech was too large to fit in the Cromwell.

The larger 75mm and shorter cartridge were mated with a shortened 17lber barrel and ammo to produce the HV 77mm
as used in the Comet.

 

[tomo pauk]

The larger 75mm and shorter cartridge were mated with a shortened 17lber barrel and ammo to produce the HV 77mm
as used in the Comet.

The 77mm HV was of the 3in calibre, ie. 76.2mm. It was capable of using the same shells & projectiles as the 17pdr.
The stillborn 75mm HV was, indeed, 75mm.

 

[WARSPITER]

Yes and the difference in name was because of the cartridge for the 77. This was different to the 17lber so rounds for
each gun were not interchangeable.