"M36 Jackson?" Topic

Hi, I know that the Americans used these, did the british? If not why?
If so which units?
Did the british have a different attitude to TD's which is why they didn't take the hellcat, the same reason as with the Jackson?

thanks hope that is clear
jon

You sure ask a lot of questions. Have you ever considered getting a book and answering them yourself?

The Brits had the Archer, a Valentine chassis mounting the 17pdr gun, and the Achilles, a British version of the M10 also equipped with the 17pdr gun. Otherwise, no.

"You sure ask a lot of questions. Have you ever considered getting a book and answering them yourself?"

Or even searching on the Internet?

I have several books, which I looked at, could not find the answer, tried googling (which I have stated several times before that I am useless at).

I assumed that no British units had the M36, which led onto the next few questions. which were why did they not use the M36, as I was wondering why the US went to a 90mm gun but the British did not?

jon

sorry for asking too many questions, however you are quite free to not answer. One final question which book should I buy?

Ciaphas,

AFAIK, the Jackson was not used by the British. However, they favored the 17lbr over the American 76mm or the M7 3" gun for their tank busting needs. Achilles (essentially the M10) used the 17lbr. I believe that is the only American designed TD in the British Arsenal.

Hope that helps,

John

PS. Ask as many questions as you like.

"tried googling (which I have stated several times before that I am useless at)."

Googled: "british tank destroyers ww2". First hit was:
link

Wikipedia, I know, but better than nothing and often a good starting point (if the articles are properly referenced).

So, are we not supposed to ask questions here anymore? Geez….

Basically, the M36 was a later vehicle than the M10 and had a smaller production run. In fact, a lot of M36 were actually rebuilt from M10A1 (Ford GAA V8 gasoline engine variants) that had been used state side for training. (An aside is that the tank destroyer units, unlike US armor units in the MTO and ETO, took the diesel engine M10 to war.)
The supply of available hulls to build the M36 on was so tight that the US even converted about 260 or so later model M4A3 Sherman hulls by fitting the M36 turret and reworking the interior a bit. This vehicle was classified as the M36B1.

For what it's worth, I have a fairly decent library of US WW2 armor references and I don't mind answering questions when I can.

One more thing Ciaphas,

Here is a an online mother load of vehicle data. nearly forgot about this one but it is a useful site complete with citations for data.

wwiivehicles.com

Hope that helps,

John

"Basically, the M36 was a later vehicle than the M10 and [snip]"

Very interesting, except that the OP was asking about British use of tank destroyers.

Well then Mike, let me clarify….

The M36 was a smaller production and the US had difficulties keeping up with the needs of it's own forces for the vehicle. Of course, there are other issues such the the British and Commonwealth forces already having the 17 pounder (Why add another high powered, flat trajectory gun to your inventory with the need to supply ammo, spare parts and training?). You also have the problem of the Tank Destroyer doctrine itself, which wasn't proving adequate in the face of battlefield experience.

I certainly hope that clears up any confusion.

Here is a study of American Tank Destroyer doctrine online that might help answer some of your questions.

PDF link

"Of course, there are other issues such the the British and Commonwealth forces already having the 17 pounder (Why add another high powered, flat trajectory gun to your inventory with the need to supply ammo, spare parts and training?). "

I think it's more likely the British wanted to introduce their own high-powered, flat-trajectory gun into their inventory instead of an American one. The Royal Ordinance were developing the 20lbr (84mm) gun at the time. It was later fitted in the Centurion tank.

Mserafin said:

I think it's more likely the British wanted to introduce their own high-powered, flat-trajectory gun into their inventory instead of an American one. The Royal Ordinance were developing the 20lbr (84mm) gun at the time. It was later fitted in the Centurion tank.

What's funny is that I edited out a section on the 20 pounder in the original version of the response you quoted but I'm glad you brought it up. I was worried that I was getting too tangential to the discussion but I agree that the development of the 20 pounder probably added weight to the decision by British military not to adopt the 90 mm.

Of course, that'll take me down the path of my Centurion geekiness which is even more tangential and a whole other story…. LOL

Or try these!

link

link

Mark Serafin wrote:

I think it's more likely the British wanted to introduce their own high-powered, flat-trajectory gun into their inventory instead of an American one. The Royal Ordinance were developing the 20lbr (84mm) gun at the time.

It's altogether most likely that the British had already introduced the 17-pdr into inventory and been killing tanks with it for some considerable time before the first US 90mm was fielded in the tank-killing role. Under those circumstances it's hard to see why anyone would wish to replace it with a gun that offers no real improvement in tank-killing power.

I'm fairly sure it would have been ARDE rather than any of the ROFs that designed the 20-pdr ("lbr" is gratingly wrong), but was development of this started before the end of the war? I thought that people were concentrating on the 32-pdr until 1945.

All the best,

John.

There was also a docrine difference, the British didn't use Tank Destroyers, the M10's were Royal Artillery, not Armoured Division.

You know, it could just be that Battlefront in an unprecedented epiphany of foresight requested the Brits to develop a different platform/gun in order to increase the number of different vehicle variants they could produce and market……just a tangential thought.

Well, British self-propelled anti-tank guns, were just that SPAT, run by the Royal Artillery. THere were however occasions when they were misused as ad-hoc tanks, and suffered accordingly.

The British didn't use Jacksons or Hellcats as they had plenty of their own SPAT guns already.

Like John says, I thought the 32lbr was the main focus of development after the 17pdr, during the war at any rate.

The 32lbr was based on the 3.7inch AA gun--A hugely powerful gun that could have been used as a fantastic tank gun if it had been developed properly rather than sticking it on a Tortoise super heavy tank…..
Am I wrong in thinking the Jackson/Hellcat was the fastest tank in the Western European Theater??

The Hellcat was very fast, the Jackson no quicker than a Sherman from my references (which are quite general, I will admit).
On a side note, I'm always amazed at the miserable people on this website who retort "read a book" when someone asks for information. Isn't the exchange of information the primary purpose of websites like this?
Years ago I remember the OFM going up and down some poor kid who asked about some detail of 17th Century uniforms. Ironic as now the OFM asks loads of questions about World War II, which it must be admitted is rather more easy to research give the wealth of material out there……..

Yes, the Hellcat was very nippy, the M36 was similar to an M10 though. The M18 really was the perfect tank destroyer, float like a butterfly, sting like a bee and all that. Many people like to criticise TD doctrine, but it really wasn't that daft as long as it was actually implemented rather than pretending TDs were tanks. Modern attack helicopters do TD tactics (I claim no originality for this, Bryan Perretts one and only decent book, A Brief History of Bltzkrieg, argues the point very eloquently).

"On a side note, I'm always amazed at the miserable people on this website who retort "read a book" when someone asks for information. Isn't the exchange of information the primary purpose of websites like this?"

It is, but fairly often the depth of information that would do justice to the question is best found in a book rather than in short excerpts here.

Fair enough, but if they know of such a book why not just give the title instead of just the 'read a book' response? I suppose it saves having to actually help but then why come here?

I'm not sure the 90mm offered much over the 17pdr, with APDS ammo and yes the British were concentrating on the 32 pdr during the war, only to realise that for size and weight reasons it was a blind alley.

I agree that we all should answer the question without smart remarks, or if they are tired of what they think are stupid questions, just don't say anything. Somehow I think it's in their nature to be a smart*** when they think they know it all. I guess some people wake up on the wrong side of the bed, don't get their caffeine, nicotine, or milk and cookies!

Years ago I remember the OFM going up and down some poor kid who asked about some detail of 17th Century uniforms. Ironic as now the OFM asks loads of questions about World War II, which it must be admitted is rather more easy to research give the wealth of material out there……..

17th C? I don't give a rat's ass about 17th C…
I have mellowed in my old age. I now realize hat half the fun of asking a question is the conversation it engenders. Sometimes, the fun is not so apparent.

I also realize that it is not always apparent what books are relevant, and separating the wheat from the chaff on Da Internets is often not easy. Thst is why I have stopped (I hope) being cranky when someone asks a question that has been asked 10 times previously.

Newbies are also not aware of the great resource that is a MP search.

"Newbies are also not aware of the great resource that is a MP search."

Mmmm, not sure about that. I have great difficulty finding stuff on TMP whch I actally know is there (as I contributed to the threads!), the idea of trying to find something which I don't even know exists…. perhaps my search skills are poor, but google it aint.

Martin Rapier wrote:

Like John says, I thought the 32lbr was the main focus of development

Aaarrrgh!

Even Martin's doing it now!

I demand Rapier's head on a spike!
(or Spike's head on a rapier, or something).

Splutter, choke, wibble…

All the best,

John.

Thanks, for all the answers. my question was perhaps a little loaded, my gaming group were looking at the heavy german cats and were wondering how the british would takle them, without obviously typhoon's etc. The US had the Jackson which has a massive gun (I thought compared to the Achilles).

I then had assumed (never a good place to start) that the Jackson like the hellcat never entered service due to doctrinal issues. Which turns out to be atleast part of the answer.

jon

"Even Martin's doing it now!"

I blame the liquid lubrication.

"my gaming group were looking at the heavy german cats and were wondering how the british would takle them, without obviously typhoon's etc."

OK, how to kill Panthers.

i) shoot them in the side rear with pretty well anything
ii) shoot them from the front with a 17 pdr
iii) shoot them from the front with anything else and bounce the shell off the underside of the mantlet into the drivers compartment (not against a Panther g)
iv) drop a salvo of 5.5" artillery (or larger) on them
v) shoot at them with a Bren gun – you get the MC for doing this.
vi) shoot them with a PIAT or similar.
vii) sneak up on them at night with infantry. Tanks don't like this, however big they are.
viii) wait for them to attack a screen of dug in 6 pdrs and 17 pdrs covered by minefields and supported by infantry and medium artillery. This works really well.

In the words of one Churchill squadron commander 'Panthers aren't too bad as you can knock them out from a flank'. Yes this is quite possible IRL, but less so in many wargames rules due to the telepathic ability of Panthers to keep their frontal armour facing towards the nearest threat at all times.

How to knock out Tigers.

i) shoot them with a 6pdr (you have to be quite close and/or using APDS from some angles)
ii) shoot them with a 17pdr
iii) drop 5.5" or larger artillery on them
vi) shoot them with a PIAT or similar
v) if feeling lucky, drop a 3" mortar bomb on the engine deck and set the thing on fire
vi) sneak up on them at night with infantry. Tanks don't like this, however big they are.
vii) wait for them to attack a screen of dug in 6 pdrs and 17 pdrs covered by minefields and supported by infantry and medium artillery. This works really well.

The same tank commander above said 'The Tigers are a bit of a sod' (or words to that effect).

The British had 17pdr AT guns available from Tunisia onwards. They always had infantry and artillery.

In the Western Allied armoury, the 17pdr was the best tank killer, yes there were bigger calibre guns around but the 17pdr was a specialised high velocity Armour Killer, with Rounds designed to improve its performance.

The 90mm was an adaption and suffer from some of the compromises that entailed. It also depends on the rule set you are using, the best way to handle the big cats on the table top is to limit them to historical numbers…

"the best way to handle the big cats on the table top is to limit them to historical numbers…"

Although sadly when facing e.g. I/12th SS at Rauray, Panzer Lehr at Tilly or the 503rd ScwPzAbt near Cagny, that is an awful lot of Panthers and Tigers….

Oh yes, I forgot. If faced with a King Tiger in a Sherman and you've never seen one before, ram it, then go back for a Firefly to finish it off. You get a medal for that as well.

Martin you forgot the 'get Bomber Command to carpet bomb them' option as practised in Normandy. Sadly German players tend to think of this as cheating…….

my gaming group were looking at the heavy german cats and were wondering how the british would takle them, without obviously typhoon's etc.

Hi Jon,

You need a set of rules that don't allow either side to keep reacting to the other's moves so that the big cats can be approached from blind spots and weak sides. With most wargame rules, if I'm moving my Shermans to your Panther's flank, when it's your go, you adjust the Panther so that its frontal armour is between it and the Shermans. It's worse if the Panther is more than one or has friends.

A double blind game will do this, though I've never played one, but a number of fellows here rave about the approach. A few games that don't follow a predictable structured turn sequence are out there that would make such historical flanking practical in a game.
--
Tim

"'get Bomber Command to carpet bomb them' "

Air support was excluded by the OP.

It wasn't hugely effective against tanks, the 503rd only had one company temporarily disabled by the carpet bombing.

Now, carpet bombing the factories, oil refineries, rail junctions, bridges….

Or simply shoot first and keep,shooting. In the "book brothers in arms" about the Sherwood Foresters, the tank commanders on a couple of occasions came face to face with Panthers and forced them to reverse or abandon their tanks simply by getting the first shot in and using the Sherman's greater rate of fire.
It was new to me but came from the accounts of men who were there and did it. Apparently even though your tank armour could take it, the shock of having shells banging your tank unnerved the German tank crew.

and those that were dead arose and walked the earth and were seen by many.

One of my Dad's favourite Bible quotes when me and my younger brother were a bit late at arising from our pits on a weekend.

This is truly a resurrection to compare with the cemeteries around Jerusalem about 2000 years ago.

Seriously though, I do know why it was reinvented.

The M36 only came pretty late in the war; even during the Bulge there were very few. The U.S. wasn't going to give them away (or sell them) until its own units were equipped first.

Many people like to criticise TD doctrine, but it really wasn't that daft as long as it was actually implemented rather than pretending TDs were tanks.

The problem wasn't how the TDs were used but the side-effect the doctrine had on how tanks were used … and designed. i.e. it's not the tank's job to fight other tanks, therefore they don't need a high velocity gun. Unfortunately, the German's failed to sign off on this idea and insisted on confronting our tanks with their tanks … or tank-substitutes like StuGs and Hetzers.

It wasn't hugely effective against tanks, the 503rd only had one company temporarily disabled by the carpet bombing.

They effectively had the company wiped out. All surviving tanks given to the two other kp and the crews sent back to Germany to re-equip. The Record of sPz Abt 503 in Normandy is notable for their lack of any real success.
21st Pz Div also lost c.10 Pz IV to the same bombing raid.

The problem wasn't how the TDs were used but the side-effect the doctrine had on how tanks were used … and designed. i.e. it's not the tank's job to fight other tanks, therefore they don't need a high velocity gun.

US tanks were designed with high velocity guns capable of defeating armour, and doctrinally they were also expected to engage enemy tanks if encountering them on the battlefield. However, their tactical role was not to form reserves to counter enemy armoured breakthroughs (which was the role of tank destroyer battalions), but to either make armoured breakthroughs of their own (armoured divisions) or to support infantry divisions (separate battalions).

Light tanks (M2, M3, M5) were designed with high velocity 37 mm gun, which also happened to be the towed anti-tank weapon of choice of the US military at the start of WWII (and AFAIK a bit better against armour than the 37 mm guns that the Germans towed around and mounted on their early Panzer IIIs). As for tank destroyers, one of the early ones – M6 Fargo – was equipped with similar weapon, though only seeing limited action in North Africa.

M4 Sherman, designed in 1941, was armed with a 75 mm gun that had a much higher velocity and better armour penetration than the known existing 75+ mm tank guns, which tended to be mainly intended to lob HE (such as the one on the early Panzer IVs). Soviet designers had already plonked high velocity 76.2 mm gun on T-34, but this would not have been known to US designers at the time M4 specs were put together. As for tank destroyers, one of the early ones that saw action in North Africa was an M3 halftrack mounting a 75 mm gun that IIRC had slightly worse armour penetration than the one on M4 Sherman.

Later on, the tank destroyer branch was faster in adopting the 76 mm guns (both in the form of M10 and the towed battalions, though the suitable of the latter to the tank destroyer doctrine can be debated) than the M4 tank designers, and the 90 mm gun also was seen in the field on M36 Jackson months before M26 Pershing made an appearance in Europe.

Later on, the tank destroyer branch was faster in adopting the 76 mm guns (both in the form of M10 and the towed battalions …) than the M4 tank designers…

The point is well made, but this detail is not quite correctly stated. In fact, from the details it is even clearer that the US TD doctrine did nothing to hold back the US tank armament in WW2.

The M10's gun was not the 76mm gun -- it was the 3-inch gun. This was a WW1 era weapon that was found to be too bulky and heavy to fit into an M4 Sherman tank turret. It was only by enlarging the interior space of the turret -- taking the top off, taking out the co-axial MG, the stabilizer and even the power traverse, pushing the trunions forward in front of the turret ring (requiring a lot of counter-weight on the turret rear) -- and reducing the weight (by taking off much of the armor) that the gun was successfully mounted onto a Sherman-based hull in the form of the M10.

The US 76mm gun M1 (and M1A1) was an entirely different gun. It was a completely new design, sharing not a single part with the 3-inch gun beyond the projectile (not the ammunition case, not even the powder, but just the projectile). For the same ballistic performance it was substantially smaller, lighter and more modern in design. It was designed specifically FOR the M4 Sherman tank, and the first upgunned models were completed by Ordnance in 1942.

It was only after this gun had been developed for the Sherman that the TD Board agreed with Ordnance to put it into their own from-the-ground-up TD design, which became the M18.

So in fact, it was tank development that led the way to more capable AT gunpower.

But the Tank Board that decided that the requirement to upgun the Sherman was not so pressing that they couldn't take the time to do it right, and so rejected as unsuitable for production the first 76mm armed Shermans. This was not due to any reading of TD doctrine -- the Tank Board gave not two shakes of a rat's tail for what the TD boys did or didn't do. Their focus was the needs of the tank force, nothing more and nothing less. They found the first upgunned Shermans to be inadequate, and pushed Ordnance to change to an entirely new turret. The new turret for the upgunned Sherman was taken from the T23 medium tank project. This second version of upgunned Sherman was ordered into production by the end of 1943.

…and the 90 mm gun also was seen in the field on M36 Jackson months before M26 Pershing made an appearance in Europe.

This again provides no indication that the tank boys were somehow being held back by TD doctrine.

The US 90mm gun M3 (and M3A1) was a modern design that provided it's larger projectile and additional punch in a gun that was similar in size and weight to the 3-inch gun.

So it fit pretty directly into turrets that could mount the 3-inch gun, but was too large for the turret of an M4 Sherman. By the time the gun was ready, Ordnance had developed a new turret for the M10 anyways, with a superior mantlet, power traverse, and an integrated turret-rear counterweight (rather than the odd duckbills of the M10). So the new gun was put into the new turret, and the M10s that were still states-side were upgunned and renamed as M36s.

There was no such path to upgunning the turret of the M4. An entirely new turret was again needed. The turret for the T-series was again upgraded and the T25 and T26 development projects were shifted to 90mm guns. The new T25 and T26 tanks would be ready ready for testing before the turrets from those projects could be mounted onto Sherman hulls for testing. So the up-gunning of the Sherman was put on the back burner, and the T25 and particularly T26 program took the spotlight. Ordnance provided the first T26 in the first quarter of 1944, but testing uncovered so many bugs to be fixed before acceptance that it didn't get into limited production until November. This is the tank that became the M26.

In fact the TD Command didn't like nor want the M36. They were fully content with the M18. By TD doctrine there was no need for a bigger gun, as mobility was the key to TD doctrine. Let the tanks sit and trade blows, the TDs were to maneuver for advantageous firing positions. But Ordnance pursued the project despite the complete lack of interest from the TDs, and found a ready market for their latest design with the commanders in the field in ETO.

Still the old wives' tale that the tanks were not supposed to fight tanks, and that the TDs prevented the tanks from getting bigger guns, will just not go away.

I hear some folks still think the world is flat. More than 2,000 years, and that idea still won't go away. So I guess we'll be reading how the "TD doctrine said that tanks don't fight tanks" for some time to come.

-Mark
(aka: Mk 1)

Mark 1, thanks for filling in the details regarding the 3 inch, 76 mm and 90 mm guns. I was mainly focusing on the 37 and 75 mm guns, and going by the memory for the details (don't have much in the way of references at hand).

Thank you for not attacking me personally. I bow to your superior knowledge. My take on tank doctrine comes from R. P. Hunicutt's book about the development of the Pershing, where he emphasizes that U.S. tanks could have had the 90mm gun earlier than they did, but that the Armored Force did not want it. (Again, it was not the TD doctrine that caused that, it was the AF doctrine. Note that after the war the TD Force was merged into the Armored Force.)

Eisenhower, in his book Crusade in Europe (IIRC) said that he was assured by the experts that the 76mm gun on Shermans would solve the problem, but that it didn't.

Thank you for not attacking me personally.

Why would anyone resort to personal attack in response to your rather clearly written post? I am expecting to see civilised, interesting and educational discussions here, with constructive responses.

As for the "tanks don't fight tanks" comment, I have no idea where it comes from, but it has been circulating around for a while. However, the armoured division doctrine could perhaps be described as "tanks don't sit around waiting for enemy tanks to fight", in the sense that they were not intended as defensive reserves, but as versatile mobile units capable of carrying out breakthrough operations and able to engage a wide variety of opposition.

US TD branch was a curious but highly specialised response to a valid tactical threat. Perhaps their doctrine could be described as "sitting around waiting for enemy tank breakthrough to fight", though an important aspect of this was also the ability to scoot around and locate good ambush locations. In principle they were potentially quite effective in their intended role, though in practice more versatile units might have been more useful in the field.

As for the Hunnicutt book and development of 90 mm armed tanks, I have not read it and cannot contribute much on the topic. That said, while wargamers usually are obsessed with the ability to stick as large guns as possible on tanks, the AF leadership may have also had some other more practical aspects of field worthiness to consider. They may also have underestimated the amount of heavily armoured (at least frontally) vehicles that the Germans would be able to put to the field in 1944.

Bringing in a bit more information from the primary records of that period …

Following is the transcript, available in the US National Archives, of a phone call between General Barnes, head of Ordnance, with General Devers, head of Armored Force, introducing the topic of the new 76mm gun that Ordnance was developing for the M4 Sherman. This cal took place in August of 1942, before the US Army had any information on Tigers, or Panthers, or even 17pdrs (I think -- not as sure about that last bit). At that time, the information available to these two was that the best tank guns in the field were:
- 6pdr (Britain)
- 75mm/L43 (Germany)
- 47mm (Italy)
- 76.2mm/L42 (USSR)

(It's kind of long, but it is the actual transcript from the archives. It was common in those days to have a stenographer listening in on calls between such high-ranking officers.)

GEN. BARNES: The new 76 mm. gun. The objective that we're after is to be able to give you, in the same space, a gun of 2600 ft .s. muzzle velocity, same power, exterior ballistics as the 3" high power gun. We use the 3" bore for the gun in order to use the 3" projectile which is under manufacture. We have to assemble a new cartridge case in it in order to get the power, so we call the gun a 76 mm so it won't be contused with the 75 or 3". Now, that gun will penetrate 3" of armor at 3,000 yds. and give you all the fire power we feel you'll probably need. And we can put it in the M4 tank without a single change in the tank except in your ammunition racks. While we're making the guns we can, of course, change the face plate on the tank and push the gun about 6" further out into the atmosphere and make a better arrangement inside the turret, because with this long gun we have to add some weight to the gun guard (recoil guard) in order to bring it into balance for the gun stabilizer. Of course we are all crazy about the thing down here because it puts you so far ahead of everybody else in fire power, and so what we want to do is to go ahead with the initial order of 1,000 guns, of which we will be able to get two or three hundred of in a month and a half and as a starter, while you people are making up your mind how many in the long run you'll want of these, and how many of the short guns.
GEN DEVERS: How much longer is this than the 75? It isn't as long as the present 3" is it?
B: Yes, it's a little longer than the 3". It's 52 calibers long. The old 3", I mean the old 75, is 35 calibers or 32, I've forgotten which.
D: Well,. what is the 3" A.A.? How many calibers long?
B: That's about 50.
D: In other words, this is 2" longer than that.
B: 2 calibers – 6" longer.
D: I think that's fine. The only thing that worries me a little bit now is that this isn't going to throw us off on our present set-up so we can get to fighting. I'm anxious to get M-4 tanks with anything in them so we can go to fighting.
B: It won't have any effect on that at all. We'll keep it off to one side. We won't allow it to interfere in any way either with this program or with the 3" guns on the self-propelled mounts. What it'll do is to put you out several years ahead of anybody else on fire power.
D: That's what we're after and it's along the proper lines. It won't complicate the ammunition supply now, will it?
B: Well, to this extent: You're going to have to have a round of ammunition called a 76 mm. as far as you're concerned. And that's different from the 75 or the 3".
D: What does this projectile weigh?
B: It's the 3" projectile.
D: The only difference is the cartridge case?
B: That's right
D: The 75 weighs 14.4. What does that 3" weigh?
B: About 15 lbs
D: There's not much difference, is there?
B: No. I would have considered using the 75, but we'd have to redesign the projectile because the rotating band wouldn't take that velocity. So we had to go to 3" in order to give you that velocity, and of course we have a nice stock of 3" on hand and are making them all the time.
D: Well, how many rounds are we going to be able to carry in a tank? Will it complicate that?
B: Well, it will reduce the number that you can carry, I don't know how much, because we haven't had time to study that out yet. Now, I thought either you, or you'd want to send someone up to Aberdeen to see the job. In order to save time we want to go ahead, with your permission, on 1,000 because of course we can stop that at any time. But time is of the essence here, as you know as well as I do, so I think we ought to start it and then work out the details later.
D: Well, all right then. This won't slow up anything we're doing?
B: That's right.
D: It's advance. It's looking six to eight months ahead.
B: That's right.
D: Well, I see no reason you shouldn't do it. I'll send someone up to Aberdeen right away.
B: All right, thanks very much

As you might see, this is a discussion about getting going on upgunning M4 Sherman tanks long before any shortcomings of the 75mm gun were even observed. The concept of upgunning the Sherman was begun specifically because there were people looking to the future potential needs, not being slow or intransigent in reacting to existing shortcomings. And TDs are not present anywhere in the discussion.

That doesn't mean there weren't cases of individuals suggesting some confusion or lack of clarity on who or how to fight enemy tanks. There were a lot of things said in various memoranda about how various officers envisioned the best use of tanks or tank destroyers.

To get past opinion or off-hand commentary (even if timely and primary) the actual Field Manuals of the time are the best documents, as it is the FMs that not only encapsulate the actual doctrine, but promulgate it, as they are the documents used to train crews and unit commanders.

The following comes from: FM17-10 Armored Force Field Manual, Tactics and Techniques 1942. This has references to how armored units should address defense against enemy mechanized and tank forces, and how armored units should attack enemy mechanized and tank forces.

(Keep in mind that this version of the FM was written before Operation Torch, so makes a lot of references to light tanks that were viewed as a more significant part of the mix at that time).

SECTION IV
OFFENSIVE COMBAT
46. General –
a. Purpose: Offensive combat has for its object the attainment of an objective by means of the attack. The organization and equipment of armored force units are designed primarily for offensive combat.
…
h. Employment of tanks. — (1) General. — In the attack, the mobility, fire power, and shock action of tanks are exploited to the maximum.
…
(2) Light tanks. — The primary mission of the light tank Units is to close with the enemy and to disrupt the hostile organization in vital rear areas by fast, bold action. This is accomplished by destroying hostile automatic weapons and personnel; disrupting communications; and overrunning command posts, artillery positions, reserves, and other installations essential to the enemy.
(3) Medium tanks. — (a) The primary mission of medium tank units is to assist the attack of the light tank units, chiefly by neutralizing or destroying the hostile antitank weapons. When organized resistance is encountered, espe- cially antitank guns, medium tank units will usually precede the light tank units for this purpose.
(b) Medium tanks also protect the light tanks against the attack of hostile tanks. When the enemy is composed of mechanized troops, a large medium tank component, if avail- able, is held in the reserve.

Please note this last comment. Even before seeing any combat, it was assumed that tank vs. tank combat was one of the assigned roles for the medium tanks of the tank force.

This is in a document that also described how an armored force was to make use of Tank Destroyers when / if they were attached.

i. Heavy tank, destroyer battalions. — (1) Organisation. — This battalion consists of a headquarters company and three heavy tank destroyer companies. The company has two heavy and one light platoon of four guns each.
(2) Missions. — (a) The mission of the tank destroyer with the armored division is to assist either by offensive or defensive action in the protection of the division against hostile mechanized forces.
(b) The battalion may be used to —
1. Protect a bivouac, assembly area, or rallying point.
2. Guard an exposed flank.
3. Protect the rear of the division.

So please note, even when a tank division had a TD battalion attached, the doctrine said to hold the TDs in reserve to protect the soft guts of the division, and use the medium tanks to deal with enemy armor that was encountered during offensive actions.

(This entire FM can be read at your pleasure online at: link

I know the whole "tanks don't fight tanks … because TDs" thing can be found in lots of secondary and tertiary writings, but when you go to the primary sources from the period it just isn't there. It is a gross simplification of a fairly nuanced tactical doctrine for how you use various weapons and troops. There is as much in the Armored Force FMs about the roles of artillery, engineers, or air units in fighting enemy tanks as their is about TDs.

Which of course gets us no closer to the M36 (from the OP), but may at least give us a better context in which to consider the question of 90mm guns in tanks.

Maybe.

-Mark
(aka: Mk 1)

Eisenhower, in his book Crusade in Europe (IIRC) said that he was assured by the experts that the 76mm gun on Shermans would solve the problem, but that it didn't.

Eisenhower was reasonably accurate in recalling this. In fact even during the war there was some hostility expressed by this most diplomatic of military commanders over the issue of the shortcomings of the 76mm gun (and, by association, the 3-inch gun).

While not quite rising to the levels of the USN Ordnance snafu on torpedoes in the early war in the Pacific, it was very much a case of the boys at Ordnance taking (and expressing) too much confidence from their own test regimen. According to the performance tests of the 3-inch and the 76mm guns, and the reports about the armor on the Tiger tank and the expectations of the Panther tank, they thought they had it all in hand.

The 3-inch and 76mm guns were in fact tested and proven to penetrate 100 – 110mm of vertical armor at normal combat ranges. Many pronouncements and predictions were made based on this testing.

If the Tiger tank had been made from US standard RHA test plates, they would have had it all in hand. But those silly Germans didn't use American armor on the Tiger. The Tiger's armor was in fact notably harder than US RHA, while still being highly ductile (not brittle), and so the Ordnance test results were not accurately predictive of real world experience in combat. Even so, Tigers weren't the real problem, Panthers were. And somehow Ordnance did not give sufficient consideration to the slope of the Panther's glacis or upper mantlet.

When these shortcomings were brought to their attention, the boys at Ordnance thought they already had the answer at hand in the form of their new HVAP projectiles. These were in fact pretty good, at least against the vertical armor of the Tiger. It took a few design changes to get them to be reliable against highly sloped plate, though, so Panthers remained a challenge even with the early HVAP. And US War Production Board prioritized the available supply of tungsten for the machine tooling industry, so it took a PAINFULLY long time to get more than a trickle of HVAP flowing from the production lines, with the addition of even more time to get it flowing into ETO.

However unlike the USN Ordnance snafu on torpedoes, US Army Ordnance did not resist the criticisms from the field, did not insist that the combat units were not making accurate reports, but rather put their efforts into upgrading their testing regimens including becoming quite involved in acquiring captured enemy vehicles for test firings at Aberdeen, so that their test results were not just against US RHA plates of thicknesses corresponding to reports of enemy tanks.

By the time the M36 and M26 field manuals were issued, the 90mm gun ammunition effectiveness charts were good predictors of practical results and included photographs of captured Panthers and Tigers penetrated in the test firings.

-Mark
(aka: Mk 1)

New life is bestowed upon a thread from 2009.

TMP link

It has been decades since I read Hunnicutt's book on the Pershing, so I got it out and skimmed over it. It seems that Army Ground Forces was the roadblock, not Armored Force. To quote from his introduction: "Unlike the prevailing Army Ground Force doctrine, the Armored Force and the Ordnance Department believed that the best antitank weapon was another tank."

His main thesis was that the T25E1 would have been an excellent successor to the Sherman, but that "the troops in Europe engaged by the high powered German tank and antitank guns, were calling for more and more armor protection. As a result, the T26E1 was standardized as the M26 (General Pershing) and even heavier armor protection was planned for the T26E5. With the standardization of the Pershing, there was no further interest in the T25E1 and the opportunity was lost to provide a successor to the Sherman with superior firepower and mobility."
(all on p.6)