"Why America never had a decent Sherman. but the UK did." Topic

YouTube link

The US failed to addopt the Firefly, the answer to the Panther,

The US had excellent Sherman's and lots of them. They were reliable and were good solid vehicles.

The 'problem' can be seen as the fact that Britain had been fighting the Germans since 1939 and the Germans were our main opponent, just over the channel. American procurement was done based on what they thought they would need, based on their faulty TD doctrine. We had fought Tigers in Tunisia (and captured one) realising quickly our tanks needed a 'Tiger Killer', and used that intelligence to aim high – hence the 17pdr.
The biggest change we made, however, was ditching OUR faulty doctrine, The Cruiser tank and Infantry support tank, though we still kept the names, oddly.

The US 76mm armed Sherman was a great ALL-ROUND tank.

Creighton Abrams turned down the 76mm Sherman. Said the 75mm model was a better infantry support tank and that was what he mostly did. And how many Sherman-armed tank battalions have those of us on TMP led in combat?

Yes, American doctrine let them down initially. The idea that tanks supported the infantry and enemy tanks would be opposed by tank destroyers let them down until the acid test of combat changed things.

The US 76mm armed Sherman was a great ALL-ROUND tank

…until it met the T-34/85 in Korea!!!

To be fair, the Sherman was a good tank – maybe not a great tank, but a very good one – and as noted it was designed for a certain tactical doctrine that did not quite work out as planned

Read up on the Battle of Arracourt, and then get back to me.

+1 John

Crew quality and experience was probably as big a factor in success as the tanks themselves. As John points out, at the Battle of Arracourt a veteran US armored division with Shermans (and NO air support) took on several brigades of German Panthers with completely inexperienced crews and totally demolished them.

and as noted it was designed for a certain tactical doctrine that did not quite work out as planned

Also worth adding that certain elements of the basic design (weight and dimensions) were influenced by logistical considerations. The USA knew it would have to load tens of thousands of M4s onto ships and sail them all over the world, so optimizing the "fit" was critical. After that was the consideration that not every destination was going to be a modern port in the UK, Australia, or Egypt, so unloading the things had to be achievable. And of course they had to be transportable by landing ships, landing craft, barges and lighters, not to mention a potentially diverse assortment of railway gauges. Oh, and not too large and heavy to operate on beaches, in jungles, unimproved roadways. etc.

It is all true but one would think "Yankee ingenuity" could have come up with a better gun after the North African experience

+1, enfant perdus
There's a very good reason that the "superior" Pershings didn't arrive until very late in the war. Liberty Ships couldn't carry as many as they could Shermans ditto landing craft. And double ditto ports. Railroads?

Gamers obsess over gun caliber, armor thickness, etc. but "Availability is the best ability." By the way, that also explains why "inferior" quarterbacks often win Super Bowls, while Hall of Famers watch it on TV. Or even pout and leave the field without the handshake after the game.

The premise is a lot like asking "Since the Germans had the Bismarck and the Japanese had the Yamato, why did the Americans waste time and effort building anything but Montanas." Ignoring, of course, the actual facts of combat. Wargamers tend to forget that Panthers and Tigers were only a small portion of the German armor force, and that both suffered from very real mechanical problems.

As for a "better gun", I value Creighton Abrams' opinion on that. And were there any 76mm guns at Arracourt? 🤔

Oh, by the way, who won the war? The "superior" German tanks, or the mediocre Shermans? Okay, fine. The Russians helped a little bit.

The US 76 mm gun M1 mounted on multiple Sherman variants had similar performance to the British 17lb QF. If the Sherman had HVAP ammo, it had superior penetration over the 17lb QF except for that gun's APDS ammo.

So that includes the thousands of M4A1(76)W, M4A2(76)W, M4A3E2 (76) "Jumbo," M4A3(76)W and M4A3(76)W HVSS Sherman "Easy Eight" tanks deployed after D-Day.

Also, the US 76 mm gun M1 was lighter than the British 17lb QF, so US Shermans were a little faster and more maneuverable than the Firefly.

What really is in the "plus" column of the Firefly is superior British optics and sights. The Firefly had 6x optical sights, the Sherman series had only 5x optical sights, giving the Firefly the edge in terms of range an fire accuracy.

Ah, this old chestnut rears its head again.

It's easy to refute:

YouTube link

Firefly was a fine adaptation of the Sherman, but honestly the Easy Eight was a great tank with a fine gun, and the various Super Shermans fielded by various nations were in use all the way to the 1970s.

Even the 75mm Sherman was a good tank. Was it world beating? No. Did it need to be? No.

US doctrine always said that tanks fight other tanks, but their primary role was infantry support and the primary role of the tank destroyers was anti-tank combat.

The US had no problems with the T-34 in Korea, Shermans handled them easily. It was the initial deployment of M24 Chaffee and small caliber bazookas that let us down.

The 75mm was a good anti-tank round but even better with HE to take on machine gun nests and other infantry support roles. Remember the Sherman was designed in response to the early war Panzer IV with short 75mm gun, not the Tiger tank.

Shermans were designed to be lifted out of the cargo hold of a freighter by the cargo booms of the freighter, since access to a port could not be assured in the attack. That greatly limits the weight.
YouTube link

Mike Bunkermeister Creek
Bunker Talk blog

Oh, and the US did use the Firefly in Italy and was ramping up production for use in Europe when the war ended.

Bunkermeister

If you need to kill a tank, I'd want the firefly

If you need to blow up a mg nest, a 75.

If you need a tank, anything.

Touching again on doctrine, the US did put a "better gun" in the field pretty damn quickly with the M10, followed by the M18 and M36.

The sheer inertia of US war production is something that is rarely factored into armchair historians' thinking. Like a modern supertanker, large scale projects were generally slow to start, awkward to reorient, and difficult to stop. Brewster delivered 771 SB2A Buccaneers/Bermudas despite the type being deemed unsuitable for combat. On the flip side, the whole raison d'ętre for the A-36 Apache was to ensure production lines for the P-51 would be running when appropriations for fighter aircraft were available again. With AFVs, this often meant models rolled off the production line with known shortcomings because there wasn't a speedy mechanism to make change orders and affect them at the factory level. Again, it's a testament to the Sherman design that many modifications and upgrades could be made post-production.

The Lee/Grant looked as silly as it did for one very specific reason. It was difficult to produce Turret Rings that could handle a turret for a 75mm gun. They already knew how to produce a ring for a Stuart gun, so that's what they had to do if they wanted to produce ANYTHING.
So, hang a sponson on the side until the ring manufacturing problem could get ironed out.
Imagine not having an absolutely perfect ring, and trying to rotate the turret. The screeching sound of tearing and rupturing metal is not soothing.

It's not just a problem of fitting a "better gun" in place.
The Hun are sinking transports at an alarming pace. So we have to be able to ship tanks that will fit in ships that can be mass produced.

Who manufactured the turret and mount for the Firefly 17pdr? Did British tanks get first priority? Even then, the British couldn't make every Sherman a Firefly.
How much modification did a Sherman need to fit that turret? Or was it manufactured with modifications?

It's a lot more complicated than "A Firefly has an AT of 14, while a Panther has a frontal armor of 12. I want nothing but Fireflies! Machine gun nests? Irrelevant."

Can a Firefly fire paint?
Does it have loudspeakers on Sponsons?
Hmmmmm?
Stop with the negative vibes.

It is all true but one would think "Yankee ingenuity" could have come up with a better gun after the North African experience

The sources I have read indicates they did come up with a better gun. The relevant commanders didn't want it. To be more accurate the relevant commanders felt the drawbacks from putting the better gun into the Sherman outweighed the benefits. Until Normandy.

So much retelling of the same old tropes.

Oh the 17pdr Firefly was the be-all, end-all of the Sherman line.

Except that Shermans remained in service around the world for another 20 years in large numbers, and 20 more after that in specific cases. Fireflies in 1950? Anyone?

Oh that American doctrine of the TDs was the reason why the Sherman was so crippled.

No bother with the Field Manuals that spell out the doctrine that the crews were trained to, which all clearly stated that the FIRST job of an American medium tank, even ahead of other explicitly directed missions, was to fight enemy armor, whenever it was found not just on the tactical battlefield but within the area of operation. No no no we know doctrine better than the guys who wrote it or trained in it.

The Sherman was meant for infantry support.

Never mind that half of the US Army tank battalions in the ETO were in armored divisions, whose doctrinal role was explicitly NOT to support infantry formations, but rather to act independently in an exploitation role (where the only infantry available "to support" would be the armored infantry, who were tasked "to support" the tanks). Or that the Field Manuals for the independent tank battalions, which did support infantry formations, clearly identified that the FIRST priority of medium tanks operating in support of the infantry was to engage and defeat enemy armor, whenever it appears on the battlefield.

The Brits offered Fireflies to the Americans, who were too proud, or too vested in their NIH to accept them.

Never mind the documentation of US Army requests for Fireflies to test, and for a committed rate for delivery to US units, that were pushed out again and again, so that it was March of 1945 when the first deliveries actually took place because, well big surprise, THE BRIT'S own production needs took priority.

For all the gnashing of teeth about the shortcomings of American doctrine, please consider the plight of the British, Commonwealth, and other Allied forces if the US had not had the Sherman. Was the Cromwell going to win the war? Remind me how many 10s of thousands had been produced by D-Day? Well OK, let's add the Archer and Covenanter in support, as we all know that only the US Army was polluted by "tank destroyer doctrine".

The US had produced, in total, about 100 medium tanks over the 20 years prior to 1940. By the end of 1942 the US was building 2,000 medium tanks per month, out-producing the Germans in medium tanks by a factor of about 5-to-1, with capacity still growing. Do you think this was a product of happenstance? A coincidence of nature? Was it somehow pre-ordained by heaven on high? Did the US Army just go down the street to the local store and find un-used tanks available off the shelf?

In 1917 the US Army needed British-made rifles and French artillery to support their few hundred thousand troops in Europe. In 1940/41 the US War Board adopted a set of doctrines (ooh, that nasty word) that supported the needs of doubling the size of the Army every 6 months for 3 years, with complete supply of every type of modern equipment from tanks to artillery, rifles, machine guns, grenades,flame-throwers, bridging equipment, light trucks (jeeps), medium trucks, heavy trucks, super-heavy trucks, roadwork equipment, helmets, uniforms, boots, first aid kits, rations, cots, foot lockers … with kit that was not only serviceable in the local conditions where they were produced, but across vast oceans in the relatively mild European theater, in North Africa deserts, Southeast Asian jungles, and Arctic tundra.

95% of the materials in the hands of the US Army of 300,000 men in 1939 had to be replaced by new materials, which had to be produced fast enough to equip the US Army of 2 million men in 1942, and 8 million men in 1944.

All of this had to be done in competition for resources, manpower and talent with programs to build the largest navy the world has ever seen, and the largest merchant marine, and the largest air force.

And at the same time the US provided large stocks of that same new equipment to British, Canadian, South African, Polish, Free French, Soviet, Chinese, Brazilian, and reformed Italian armies.

So please consider what was more important -- having a tank that impressed the amateur historians, or having a tank factory that impacted the world's battlefields.

Show me one military campaign where the outcome was significantly influenced by the presence of Panthers and/or Tigers. Or by the lack of Fireflies.

This is the context of one of the most successful and important tank programs in history. Only one other tank (the T-34) can even compete with the overwhelming success of the Sherman program. These were remarkably productive weapons systems that were used to drive armies forward to victory … all unfortunately achieved without due consideration of the dismay and discouragement that would haunt wargamers for decades to come.

If you need to kill a tank, I'd want the firefly

If you need to blow up a mg nest, a 75.

If you need a tank, anything.

This is an interesting perspective. I don't necessarily agree with the details, but I like how it spells out some of the issues beyond just "I want big and bad for the joust on my wargaming table".

So if I might borrow the format:

1. If I expect to fight against a tank, I probably want a Sherman 76.

2. If I expect to fight dug-in infantry, I want a Sherman 75.

3. If I want to win a campaign, any tank (but preference to any reasonably reliable medium tank).

Details:
1. Sherman 76 is faster on target, more likely to hit, and faster to get off subsequent shots than any peer. It is highly effective against the enemy armor I am most likely to face (Pz IV or StuG). If I am LUCKY enough to have a few silver bullet HVAP rounds it is about as effective at medium range as a Firefly against the reasonably likely Panther or occasional Tiger's armor. Less so at very close range where Firefly's lucky-to-have APDS has some chance of hitting. But alas, I am not very likely to be so privileged, so I will have to rely on the "first to shoot is most likely to win" phenomenon.

2. I am actually not very worried about MG nests. I can put 2 or 3 76mm rounds into one if needed to support the local GIs. But I am VERY concerned about dug-in PAKs. They are the single biggest threat to my survival, faced far more often and generating several times more losses than Panzers, and I want to be able to hit them with the most effective big bang I can as fast as I can.

3. The Germans managed to bring armor to about 2 out of 10 battalion-sized attacks. This was as much due to StuGs, StuHs, and JgPzrs as it was to actual tanks. The Soviets managed to bring armor to perhaps 3-4 out of 10 battalion-sized attacks. The US Army in ETO managed to bring armor to almost 10 out of 10 battalion-sized attacks. The typical German infantry division had no armor. The typical US Infantry division effectively had more armor than the typical German Panzer division. This was the war-winning formula. It wasn't 5 Shermans vs. 1 Tiger on the battlefield. It was US armor on 5 battlefields, vs. German armor on 1. That's how campaigns were won.

-Mark
(aka: Mk 1)

To paraphrase, if not echo, what others have said:
1) The most important ability is availability. It's better to have several Shermans on the battlefield than one Tiger or Panther in the repair shop.
2) Identifying a target firing first is more important than the tank type. Many years ago I visted the panssari museo (tank museum) in Finland. IIRC correctly there was a battle in which Finns in T26 and T28s defeated a force of T34/85 that had them outgunned and outnumbered.
3) What is more important to an individual tanker may not ne what is most importan to the general in charge of logistics as others have pointe dout. And it's logistics that win wars.

Mark 1.

I knew I liked you for a reason. You nailed it in you last post.

The introductory page of the 1977 US Tank Gunnery manual talked about tank gunnery in WW2. The primary sight was the V system still used in the 1970s by the LAW, Dragon and the Sheridan.
It took 13 shots by a stationary firer to have a 50% chance to hit the target.

When I was at the Advanced Quartermaster course, I worked on updating manuals. I had a chance to review the study from WW2 that discussed the shipping of tanks to Europe. It compared not only the number of medium versus heavy tanks and why they decided on medium chassis tanks. A big favor was firepower ratio. I did not agree with that conclusion because even though a cargo ship had more firepower, it was inferior guns.

Bunkermeister That was new to me, that the US belatedly took uop the 17 pdr very interesting. How many did they get?

I never said the 17pdr was the best tabk ever. and yes the Sherman continued in use very late after the war in the '67 war in some numbers but you would expect that. The Brits recognised that a mix of Firefly and 75mm were needed so even the Firefly had some limitations. The video notes the 90mm was not really a gain over the 17pdr re anti tank and was too late to save Dherman tank crewa as they only had the 76mm.

Now it is true that even 75nn Sherman tank crew had a far greater life expectancy than that of an infantryman, but it does seem a shame that a better timely gun could not have been addopted by the US.

Regarding tank weight it's noted crews were not complaining so much about lack of armour of a Sherman, in a fight between a tiger or Panther'and a Fierfly there was little to choose as both could penetrate the other's armour so it counted little.

An old subject for sure, but what a great discussion has resulted. Late 1944/1945 gimme a Jumbo with a 76, so long as all my pals have a 75 to deal with the biggest threat by far, A/T guns and dug in infantry, with those nasty little fausts and schrecks.

There is so much to this subject, it could actually merit a whole book on myths and reality of the Sherman tank in WWII. I think it would do well.

First myth is that the US did not want the 17 pdr.

For one thing the US army is big enough that you had contrary voices even within it. While there was a lot of "Didn't invent it here" syndrome, there was an equal or larger number of people who realized the potential of the gun and did in fact want it.

Those against it were living in the hope of the gun coming just around the corner, the 76mm. The only problem was the hype was overpromising what it could do. Anyone ever see the pictures on Pattons face when he walked away from a trial demonstration of a 76mm against a knocked out Panther??? Or maybe how Eisenhower was all bitter because he was promised thhat they would be able to knock out Panthers???

Anyway,,, some actually did want Fireflys in US service. The problem was the ability of the UK to convert the vehicles was alreeady at maximum panic levels of production for conversions. They had a mad scramble just to get enough converted so that armoured units going to France had merely one in every platoon of four tanks. (UK tank platoon is called a troop and had four tanks)

The UK actually committed to providing them only once they had at least two tanks per troop or platoon converted. By the Battle of the Bulge the US actually had either fifty or a hundred in training, but then gave up on it and returned them to the UK.

Any questions, read the Sherman Bible by Hunnicutt.

Even more interesting, the US knew extensively about the 17pdr.

The T23 turret on the later Shermans with the 76mm gun was designed so that the trunnions would accept either the 76mm or the 17pdr! It was designed to accept even other guns like the 105mm howtitzer I beleive but need to check up on that one. But why waste a brand new 76mm gun barrel before it was worn out?

The 76mm while it had a better AP performance than the 75mm, also still had a fair HE round so it was more useful overall.

Perhaps knowing about each gun was not as important as what the deesigners had in hope of their upcoming special rounds.

The initial British APC and APCBC rounds were good traditional rounds. Likewise but only a touch less so the US APC and APCBC rounds. But you see the designers overpromised in the development of their specialized ammo.

For the UK it was the revolutionary APDS or sabot rounds as we call them today. These went through whatever they hit back then. Onlt problem was they were incredibly innaccurate as the distance opened up. Past 500 to 600 yards they were considered near hopeless. The accuracy issue was not actually solved until the late 1940s and today sabot rounds are the best thing since sliced bread.

In the US, the accuracy issue ruled supreme and so the British gun was considered not a good choice because of being only marginally better than the 76 with traditional APC rounds and wildly innaccurate with the special rounds.

However, US hopes in developping their special round were kind of crushed too. They decided to merely boost the speed and devlepped the HVAP. While they did get the velocity improvment, the accuracy suffered a bit and there were a number of problems in the round shattering on impact. Evenetually problems were overcome. It did do better than the regilar APcC and APCBC type rounds but productions delays and quantity were limiteed with actual ammo being given out sparingly or preferably to the tank Destroyer forces rather than to tank troops themselves.

There are lots of accounts of what a special occasion it was that a crew was given two or three of these rounds. Worse yet about how a tnak crew would just about sell their birthright to trade a tank destroyer crew for one or two of these rounds.

Everything is a compromise.

deadhead +1

It seems that my earlier questions about manufacturing and compatibility were rather… valid. 🙄

Oh yeah, UK conversions were strictly of the 75mm turret versions. The later T23 76mm turret didn't start appearing until after what July?

It was a bit of work. Back of the turret cut out and then extended in a box to get the radios out of the way of the breech and recoil. Front of the mantlet cut out and then adding chin fillets to extent the trunnions forward in order the fit the longer breech block into the turret. Fit the gun in a 90 degree turn to make it possible to load from inside the turret. Then revamp the ammo stowage by removing and replacing all the racks, including losing the co-driver position and blocking off his MG.

It was a lot of work for the specialized REME workshops who were about to recieve countless tanks damaged on the battlefield.

Welcome back Mark 1, have not seen you for a while.

The Panther is a medium tank because the Germans classified them by the gun size, not the weight. The IS-2 and Pershing weighed about the same as the Panther but were heavy tanks. If they put a 20mm gun on a Panther would it be classified as a light tank? The Panther weighed about 10 tons more than a Sherman so it's not a fair comparison.

A lower-velocity gun like the short 75 allows you to use a lighter shell casing to pack more explosives into it. Lower velocity also makes the gun more accurate when engaging targets on the ground. That's why infantry artillery has short barrels.

The Sherman's advantage in getting off the first shot was the commander's turret override. No other tank in WWII had it. This allowed the commander to engage and shoot without the gunner.

This is another example of using HE. The Sherman short 75 can do this but the German delay fuse was twice as long so the round flew further and higher and not as effective:

Sherman 75 HE on a Panther turret:

Sherman HE against a Tiger:

This should be definitive proof. The Panther D model during mid 1944 had a 6 degree per second traverse rate to the Sherman 25 degrees:

Early Sherman models in N. Africa had flawed armor casting and a poor periscopic gun sight which had up to a 4 mil aiming error. These deficiencies were resolved by June 1944.

At Normandy and after, Shermans were using WP rounds, which gave them a huge advantage too. Some tanks carried up to 30% WP rounds.

Unfortunately, most of these advantages are not used in games I'm aware of (except mine).

Shermans had an APU that could be used to charge the batteries without running the main engine, thus saving fuel.

The turret was traversed electrically so it was silent and not needing the engine running. The Panther A and G models had a variable turret traverse based on engine RPM. To get a 20-degree-per-second traverse rate the driver had to rev up the engine almost to the red line. This could accidentally blow the engine. It also threw up a plume of exhaust smoke, giving away the Panther's position before it could fire.

Panther gun simulation against Jumbo: YouTube link

Sherman units that did use the gun stabilizer allowed the gun to remain level while decelerating, allowing it to perform a halt fire a few seconds quicker. Every second counts in getting off that first shot.

The muzzle blast of early 76 mm guns obscured the target with smoke and dust. This could prevent the gunner from seeing where the projectile struck. The Ordnance Department initially reduced the amount of smoke by using a long primer that gave a more complete burn of the propellant before it exited the barrel. The revised ammunition began to be issued for use in August 1944.

Muzzle brakes, that redirected the blast left and right, were tested in January 1944 and authorized in February 1944, with production starting in June 1944. Mid-production guns (M1A1C) were threaded for a muzzle brake, with the threads covered by a protector cap. Enough muzzle brakes were produced to allow them to be released onto M4 production lines in the fall.

For those vehicles that did not have a muzzle brake, once the Armored Force began to accept M4s, it was recommended that tank commanders stand outside the tank and "spot" the strike of rounds to guide the gunner. If the blast obscured the target for 2 seconds, the gunner would not be able to see the result of the shot on the target if it was under 1500m unless he saw a ricochet go up in the air.

I think the bottom line is that any tank concealed for an ambush will shoot first. With all engagement factors equal and the Allies having more tanks, the quicker engagement time, faster rate of fire, and use of WP rounds would give the Shermans an advantage that would be hard for the Germans to overcome.

Wolfhag

Timeportal, about the accuracy issue.

Accuaracy is more of an issue of gunnery and training. Indian tank units in Burma would routinely expect their gunners to be able to hit jerry cans at 500 yards first round.

I think both the UK and US were victims of their own pre war doctrines until far too late. Even as early as 1942, Montgomery was known to tell his chain of command that he wanted nothing but Shermans in the future. As despised as many are of him, give credit in his recognizing the need for the 'universal tank', or as we call it today the do everything MBT.

The 76mm Sherman was a fine tank against most 1944 contemporaries, It wasn't a heavy tank, and wasn't designed to be. As for the low HE throw weight, just fire more HE shells at the target…

The 17pdr Firefiely really was essentially a lashed up tank destroyer, albeit with an enclosed turret. The Centurian was a far better tank.

Funny no one ever gets all tied up in knots comparing the Isreali Sherman M50 with the french 75mm gun?

Really the same issue. A small turret early Sherman with the stubby 75mm getting upgunned to make it compatible with whatever they came up against on the battlefield for the mid fifties.

Fascinating thread this (something I don't usually associate with Shermans).

My take away from this is that the 75 plays to the strengths of the US in WWII.
It's adequate, numerous, reliable, fixable, transportable and present.

What more do you want?

It is a bit funny because no one considers the other side of the fence either.

The Tiger and Panther had every idenetical problem that any allied tank had on the offensive. The first ones were after all taken out by well sited anti tank guns. Both British six pounders and soviet 57mm Zis2s. While on the defense, they were subject to artillery or air attack.

The 17 pdr, 76mm M1 and even the French 75 CN75-50 were all responses to panic of the uparmoured German freaks of nature tanks.

As a point of note, the 17pdr, 76mm and even the 75mm CN-50 were all left and used as they were for years. The only tanks modified further were in fact the late model 76mm gun tanks because the T23 turrets were the only turret models that would accept the Isreali/French 105mm with the D1058 gun.

Of course by the time they modified the 76mm turrets into M51 turrets, the Shermans were already twenty years old! So yeah, even the 76mm turrets lasted twenty years and more in front line use.

in 1982, the UK was actually under the fear that they would face Argentinian Fireflies. Forty years on.

My take away from this is that the 75 plays to the strengths of the US in WWII.
It's adequate, numerous, reliable, fixable, transportable and present.

Overpaid, oversexed and over here?

Accuracy is more of an issue of gunnery and training.

I would disagree.

Practical accuracy can include issues of gunnery and training. But a gun, any gun, also has a technical accuracy, which defines the dispersion (variance) of shot based on a constant point of aim and range.

Even if you are a perfect gunner – the gun itself has a technical accuracy that will give you some probability of hitting what you aimed at.

This will then be affected further by the fact that you are not a perfect gunner. And you are not firing in a perfectly managed and known environment with all variables fixed.

An accurate gun will get better results with a better gunner in a better situation. But an inaccurate gun will always be an inaccurate gun no matter how good the gunner is.

US Army Ordnance and British War Office testing only measured the dispersion (technical accuracy) of the guns. It made no judgement of the skills of the gunner, the stresses of the environment, or the state of the gun or ammo. In this, it may be regarded as the limit -- the best that could be achieved in the best circumstances. Real world combat results could, and did, differ significantly.

Here are some reported results from British testing of the technical accuracy (the dispersion) of tank-mounted guns firing anti-tank ammunition in 1944, from WO 291/238 AORG Report No.256 "The Importance of Gun Dispersion in A.P. Shooting". All tests were fired at 1,000 yards range:

6pdr APCBC ………………. 5.2mins
75mm M3 APCBC(M61) ……….. 2.2mins
75mm Mk.V APCBC ……………3.0mins
76mm APCBC ………………..1.4mins
17pdr APCBC ……………….5.2mins
17pdr APDS ………………..12.0mins

Please note this is British testing -- no US NIH bias presented here. The smaller the number (lower minutes-of-arc), the smaller the target area you could count on hitting. Per these results, a perfect gunner firing 17pdr firing APDS ammunition could rely on hitting a Navy cruiser only if broadside (not nose-in) at 1,000 yards.

Here are some more results of technical accuracy from British testing, in this case from WO 291/751 AORG Memo No.427, 24th Nov 1944, "Comparative Dispersion of Tank Guns". Here the testing measured the probability of obtaining a hit on a target 2' high by 5' wide (aiming at the center of the target) at a variety of ranges. This size is roughly coincidental with the size of a Panther's turret face

Range: ………………. 500yds; 800yds; 1000yds; 1500yds:
Churchill IV 6pdr APCBC 150rnds…74%…73%…62%…42%
Churchill IV 6pdr APDS 90rnds…..74%…50%…37%…20%
Sherman 17pdr APC 100rnds………88%…66%…52%…32%
Sherman 17pdr APDS 40rnds………42%…21%…14%…7%
Comet 77mm APC 40rnds………….98%…86%…76%…53%
Sherman 75mm M3 APC M61 150rnds..100%…96%…90%…73%
Sherman 76mm APC M62 40rnds……100%…100%…96%…92%

US guns were consistently demonstrated to have been built to a higher standard of technical accuracy than British guns. The US 76mm gun was notably accurate, more so even than other US guns.

The case might be made that US Army Ordnance standards of technical accuracy were in fact excessive. Even though the US 76mm gun was measurably more accurate (technically) than the 17pdr,

the truth is that the 17pdr firing APCBC was serviceably accurate -- it could reliably hit tank-sized targets at combat ranges if aimed well. And given it's higher velocity, errors in range estimation (in combat) had less impact, generating smaller errors in elevation, so it was easier to aim well enough to hit tank-sized targets at combat ranges.

But even at 500 yards, a perfectly aimed 17pdr firing APDS had less than a 1-in-2 chance of hitting a Panther's turret.

Out to about 1,000 yards the 76mm HVAP round had roughly similar likelyhood of penetrating a Panther's turret front (mantlet) as 17pdr APCBC. Neither had a reasonable chance of penetrating the glacis, unless getting a lucky hit on the MG ball mount, driver's viewport, or perhaps a weld seam. 17pdr APDS could in fact penetrate the glacis if it could hit it. But many shots would be needed to give a reasonable chance of a hit at 1,000 yards.

US Army Ordnance did comparison test firings of the 17pdr vs. US 76mm and 90mm guns in 1946. In this case the target was 4.5ft by 5.5ft, which is a bit smaller than a Panther's glacis (setback at a sharp angle), at 1,050 yards. They fired 38 rounds of APDS, and got only one single "fair" hit which was not useful to their analysis (it struck where another round had also struck), and one hit they judged to be not a fair hit (penetration was so shallow they judged it had struck the ground short of the target and ricocheted up to strike it side-on). After 38 rounds fired they gave up.

These kinds of results (I have more test results -- all are pretty consistent on these issues) are what led to my conclusion that a 17pdr would give advantage against a Panther only at very close range.

-Mark
(aka: Mk 1)

God this is fascinating.

There is so much info out there, for someone like me, who thought he knew his way around Shermans.

Reliability and ease of manufacture, leading to sheer numbers on the field. I tend to ignore that as, if I was one of the five M4 variants just happening to face a King Tiger, on that very rare occasion, I would be jolly hacked off to see my hits bounce off. Tell me about destroying their optics or jamming the turret traverse. I want to see it burn, before I do.

The compromise between sheer size, if to transport its weight, to ship, the main gun type, then to meet enemy armour or, much more likely, A/T or entrenched infantry. The protection of the armour, the chance of getting out (far better than suggested), the flammability of gasoline vs Diesel, (when the stored ammo was actually the hazard)

So many more myths and some realities

There is a book in this and it would have much novelty

It might be interesting to research "Ford Quality Control during World War Two".
I will leave this as an exercise for the student. 😄
Basically, Ford attained "six sigma" by researching exactly where defects originated and eliminating the cause. It sounds elementary, but Ford went fanatic about it.
In a nutshell, all spare parts fit perfectly.
Okay? So?
An Italian or German mechanic was basically a craftsman. He would take a spare widget, and file or bang it to fit.
An American mechanic took the frammis out of its box and put it in place and it perfectly fit. Thus any farm boy, or city boy, could get a tank back in action in a fraction of the time it took a German craftsman mechanic crew to do it.
American gear was designed for this simplicity of repair.
Take one look at the road wheels on a Panther and ask yourself "Why?"

Apply this to the above question of turrets.

Henry Ford's affinity for Nazism, Fascism and virulent antisemitism is a different story altogether. 🙄
Ditto the German product of Opel trucks. They were very scrupulous about royalties and scrupulously deposited them in escrow in Swiss banks.

Mark 1,
Didn't the 76mm shell have problems when it first came out in the field, not performing as it did during testing by Ordnance? Something about testing against vertical armor with a different hardness than the Germans had? Wasn't there a problem with cracking and shattering at close range against sloped armor? Especially for rounds hollowed out for a base detonating HE charge? Also, shattering of tungsten rounds because of brittleness?

Something the war games don't take into account is that a round normally needs to penetrate 120% or more of the armor to fully penetrate into the compartment and bounce around and do damage. If a round penetrates 75mm into armor that is 75mm you'll most likely get spalling damage.

Wolfhag

To simplify…
If a part on the Drawing was supposed to fit the gizmo flange into the whatsit hole, the flange has a dimension of 57.5" +/- .25".
That means that technically both 57.25" and 57.75" are in spec. So is the hole it fits in. BUT if the whole specs out small and the flange specs out too large, the part will not fit. And if the reverse applies, the part will be too loose.
So, Ford engineers tried with might and main to produce with six sigma accuracy at the 57.5" dimension, with much smaller tolerances. It required much tsorris and agita on the floor. And Luke from Nebraska could take the part out of the box and proceed to the next step.
British manufacturing did not have this step, nor the Germans.
And that contributed to the "availability" of American goods.
Yes Ford shared it with AMERICAN manufacturers.

Ironically, Toyota adopted and refined this technique after the war, and combined it with "rapid die change". Ironically, Toyota used it on surplus Ford presses.

Yes. I was deeply involved in manufacturing, and took many Quality Control/Assurance classes.

To give you a better idea of the HE effectiveness:

75mm HE at 30 feet from the blast site has 470 fragments capable of penetrating 1/8" of mild steel at an initial velocity of 3,120 f/s.

76mm HE at 30 feet from the blast site has 240 fragments that are capable of penetrating 1/8" of mild steel at an initial velocity of 2,260 f/s.

90mm HE at 30 feet from the blast site has 388 fragments that are capable of penetrating 1/8" of mild steel at an initial velocity of 2,900 f/s.

105mm HE at 30 feet from the blast site has 900 fragments that are capable of penetrating 1/8" of mild steel at an initial velocity of 3,500 f/s.

Info source: PDF link

Wolfhag