Paul Vebber
Posts: 11430
Joined: 3/29/2000
From: Portsmouth RI
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Paul,
Whenever "is A better than B" gives a "complex" answer, the reality is that it was a bit narrower than everyone thought IMHO.
Complex enough to have a nearly 600 page book written about the "rest of the story" :) Usualy when "A is better than " is assumed cut and dried, its by someone examining the case in hindsight IMHO.
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If the AORG had tested the Sherman 76 or 75 against the Panther 75, there would have been nothing complex about the answer, would there?
Hunnicuts book never references any of the datasheets to AORG reports. Given the 17lber was only slightly inferior tothe Panther 75 one would think it would have been a no brainer to just install it, no? Well in the wordsof Hunnicutt:
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An ideal solution to the armament problem would have been the adoption of the British 17lber as the standard Allied tank gun. Such a decision, taken in 1942 would have insured quantity production of 17lber pounder Shermans well before D-Day. Instaled in properly redesigned turret such as that used with the 76, the 17lber would have provided the Sherman the firepower equivalent to the german Panther's 7.5cm KwK 42 and it would have been available in quantity fo the campaign in northwest Europe. Fitted in a larger turret, its operation would have been far more efficient than the improvised installation on the British Firefly.
Hindsight can easily show what should have ben done. Unfortunately, thing were not at all that clear at the time. The suggestion to adopt the British wepon was made by Col G.B. jarrett and others but their recommendation was rejected. As that time the 76 appeared to be more than adequate as far as power was concerned and it was a much lighter weapon. Its smaller cartridge case was easer to handle allowing a higher rate of fire and a larger ammunition supply. As a result, the 76 was selected as the new tank weapon and, as we have seen, even it had to overcome serious objections. (veb - referring to the Tank vs TD doctrinal debate, and the arguments over dual production of a medium and a heavy tank (detailed in Hunnicutt's other book Firepower a history of US heavy tanks - in which it describes the decision that it was better to have 2 30 ton class tanks than 1 60 ton tank - for a number of reasons including the anticipated dificulty developing the required bridging equipment to allow the operational manuever of such as the M6 in France).
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I'm not extrapoloating anything, its just that I seem to be the only one listening to the Americans on the ground (despite not speaking the language) whilst everyone else tries to tell me everything was fine (albeit only in a complex sense on paper. )
The Sherman wasn't crap in 42/43, it was just relatively obselete by 1944.
So then you must consider the Panther to be a similar failure, as its early mechanical unreliability resulted in "Germans on the ground" bemoaning its inability to get to battle, and its late armor quality problems that resulted in "Germans on the ground" decrying its vulnerability to 122 and 152 HE. IF "users on the ground" complaining about a weapon are grounds to consider it crap (your words) than pretty much every weapon made has been 'crap' in someone's eyes. Those of us not "listening" are not trying to say 'everything was fine' just that RELATIVE to other SIMILAR vehicles (ie medium tanks) the Sherman was one of the better examples, all things considered, of the war.
The 75 M4 was a decent vehicle compared to the MKIII and MKIV Panzers, the Valentine series, and the early T-34s. The 76mm was comparable to the Cromwell, the late MKIV Panzers, and was comparable the T-34/85 (very good specimins of which were better, but production quality varied so much that a great deal of them were not due to flawed armor, defective power trains and bad lots of ammo.) Its continued modification and performance in the Arab Isreali wars demonstrated it was hardly obsolete.
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What does Hunnicut have to say about the 76mm in the narrative?
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OCM item 17202 of 11 Sep 1941 outlined the military characteristics of the M4 tank. It included the provision for interchangable turret face plates which could be used to mount a variety of armament. The proposals for the improved Shermans showed the 105 howitzer and 3in gun as alternatives to the 75mm gun M3. The 3 inch gun M7 had better armor piercing performance and as already standardized as the main armament of the heavy tank M6. (veb - you can't examine Sherman development in isolation of the M6 development and the whole doctrinal triangle of medium tank, heavy tank and tank destroyer, and its collision with operational reality. But I'm sure I'm making it overly complex ;) )
However it was considered too heavy for installation in the medium tank turret. A weapon was needed which would have the armor penetration of the 3in gun, but could replace the 75 in the standard m34 ount. To achieve this objective, a developmental program began for a new gun designated a the 76mm gun T1.
Although referred to as a 76mm gun, the experimental cannon actually had a 76.2mm or 3in bore. o shorten the development cycle, the projectiles for teh standard 3in gun M7 were adopted for the new weapon. The powder charge in a smaller diameter cartridge case ws adjusted to obtain the same 2600ft/sec muzzle velocity as the 3in gun. The barrel ws lighter in weight than the 3in tube and, as originaly desinged, had a bore lenght of 57 calibers. Fitted with the same breach ring assemply as the 75mm gun M3, he new weapon could be installed in the standard combination gun mount m34.
Two 76mm guns T1 were manufactured and shipped to Aberdeen Proving Ground for tests starting on 1 Aug 1942. One gun was fired on a fixed test mount and the other was installed in the turret of an M4A1. In the M34 tan mount the long barreled canon was badly unbalanced. This was primarily corrected by cuting 15 in from the muzzle end of he tube and adding weight to the breech ring. After completion of the firing tests, Aberdeen concluded that the 76mm gun T1 was satisfactory for use in the M4 medium tank series with the modifications specified.
Based on the early test results, the Ordnance Committee on 17 Aug 42 recomended that the M4 armed ith the 76mm gun be classified as Substitute Standard. The T1 gun was also standardized as the 76mm gun M1 and his was added in parentheses to the tank's designation when it was armed with this weapon. (nomenclature examples omitted...and in the future) At this time it was planned to modify production orders to provide fo he manufacture of 1000 76mm tank gun tanks.
The testing program cntinued at Aberdeen with a production 76mm gun M1 now installed in medium tank M4A1 serial number 549. This tank carried the weapon in the newer cobination gun mount M34A1 equipped with a direct sight telescope. Elevation for the 76 in this mount ranged from +25 to -12.5 degrees. A number of minor changes were aso introduced. these included the use of a new turet front plate and spacer which moved the gun forwrd 2 inches. This provided more room behind the gun preventing interference between the recoil guard and the radio. The gun was balanced by adding weights to the recoil guard. This was necesary to permit proper operation of the gyro-stabilizer. Stowage space was provided for 83 rounds of 76mm ammo.
Like the earlier par of the program, these tess indicated that the 76 could be satisfactory installed in the M4. They also showed that much greater accuracy was possible using he M51(T60) 3-power direct sight telescope ver the earlier sight. However the turret itself was now terribly out of balance when fitted with the long barreled canon. On a 30 per cent slope it was extremely difficult to traverse, lthough both the Westinghouse and Oilgear systems succeeded in doing 20. An 800 pound counterweight at the rear of the turret was recommended as a cure for the unbalance and it was suggested that the weoght be aded to the stowge box. Once balanced, any standarddrive mechanism could easily traverse the turret.
12 medium tanks M4A1(76M1) were produced at Pressed Stel Car COmpany for evaluation by Aberdeen, the Armored Force Board, and the Tank Destroyer Board. On 2 Feb 43 one of these tanks arrived at Fort knox folllowed a month later by another. These tanks incorporated many modifications recommended by Aberden including the counterweight added as a turret bustle. Service tests begn immediately and continued on a 24 hour basis wih a final report being submitted on 5 Apr 43.
The Armored Force did not agree with the earlier test results. They concluded that the turret arrangement was inadequate mainly becasue of inadequate space. They pointed out that the tank represented a "quick fix" design that was improvised from available componenents to achieve rapid production. This was, of course, true and it reflected the original intention to produce lareg numbers of 76mm gun tanks prior to 31 Dec 42. fer rejection of the vehicle by the Armored Force, the Ordnance committee revoked the Substitute Standard classification and cancelled production of the 17 additional tanks which had been authorized to equip a complete company. they recommended that Aberdeen Proving Ground, the Armored Board, and the Tank Destroyer board each retain one of the 12 tanks already manufactured. The remaining nine were rebuilt as standard 75m gun vehicles.
The Ordnance Committee action of 3 may 43 which ended the medium tank M4A1(76M1) also recommended the manufacture of two pilots of an improved design mounting the 76mm gun. These vehicles, designated the medium tan M4E6, were to be fitted with the turret and gun mount developed for teh medum tank T20 series. For the first time, ammunition stowae below the sponson line was also recommended. This was a major step toward reducing the ulnerability of the Sherman to ammunition fires. The new welded hull with the cast front and larger drivers' hatches as incorporated into the design. Par of the turret basket was removed to allow access to the ammunition now stowed on the hul floor. the 76mm racks were lso surrounded by waer tanks to reduce the fire danger if he hull was penerated. The additional space required by this "wet storage" reduced the number of 76mm rounds to 71.
The new cast turret installed on the M4E6 was a preproduction version of the turret developed for the medium tank T23. he tank commander had the same rotating split circular hatch as on he 75mm gun Sherman and a double door rectangular hach was provided in the turret roof for the loader. The 76mm gun M1A1 and a coaxial .30 cal MG were carried in the combination gun mount T80. (some detail of the turret construction omitted)
The two M4E6s were buit by Chrysler at Detroit and one was retained at the Arsenal fot est purposes. The other pilotwas at Aberdeen Proving Ground in July 43 and shortly thereafter was shipped to Fort knox. Firing tests began at once nd a etter report from the Armored Board dated 17 Aug 43 recommended the immediate production of tanks based on the M4E6. Numerous modifications were required but none were of a serious nature. The T20 series of tanks, fr whichthe turret was origianlly designed, were equipped with a hul mounted roroclone blower. SInce the Sherman did not have such a bower, additional ventilation was needed to remove the powder fumes from the turret. This and other modifications were applied to production vehicles.
The Army Ground Forces requested 1000 M4Es and the Chief of Ordnance was instructed to discontinue production of the 75mm gun tanks. However, the armored force indicated that it did not want to completely drop the 75mm gu. They pointed out that the HE projectile for the 75mm gun was superior to that for teh 76. The M48 75mm shell weighed 14.7 pounds with an explosive charge of 1.47lbs. This compared to only 12.9 pounds with .86 lbs of explosive for the 76. Objections were also raised to the muzzle balst of the 76 nd he resultant target obscuration from smoke and dust. The larger rounds for teh 76 were more difficultto handle in the turret and fewer could be carried. Agaisnt these objections the ony advantageof the 76 was its suerior armor piercing performance. Its would penetrate approximately 1 in more than the 75mm gun M3 at the same range. In battel this would prove to be the all important factor, but that leson had to wait unitl the Summer of 44. After the Normandy fighting agianst the heavily armored German tanks, even the 76 was considered inadequate and more powerful hole punchers were sought.
The M4E6 remained at Fort Knox and was used as a test vehicle to help solve some of the problems with the 76. Target obscuration was greatly reduced by the installation of a muzzle brake. The long primer improved the burning of the powder, reducing the smoke and the muzzle brake deflected the gases to the side minimizing the dust kicked up by the blast. Based on the test program, it was recommended that all the 76s be equipped with muzzle brakes. hen the end of the barrel was threaded for a muzzle brakethe M1A1 was redesiganted as the 76mm M1A1C. A later model designated as teh 76mm gun M1A2, differed in having rifling with a tighter wist. Rifling the M1A2 made one turn in 32 calibers while that in the MA1 turned once in 40 calibers. The tighter twist improved projectile stability producing a slight increase in penetration performace at longer ranges. All of the M1A2 guns were equipped with muzzle brakes.
the standard 76mm armor iecing round was the APC M62. This was a capped projectile fitted wih a balllistic windscreen (APCBC) to reduce the drag and improve long range performance. Late production rounds were explosive loaded using a base detonating fuze. After the appearance of heavily armored German vehicles, a rush development program introduced the M93 hypervelocity armor piercing (HVAP) solid shot. This was a lightweight shot with an aluminum body and a tungsten carbide core. Frequenly referred to as armor peircing composite rigid (APCR), the low weight resulted in a muzzle velocity of 3400 ft/sec compared to 2600 ft/sec for teh APC M62. The high velocity combined with the high core density greatly increased the armor penetration. Although the velocity decreased more rapidly with the lightweight projectile, its armor piercing performance still exceeded that of the standard round at ranges greater than 2000 yards. Rushed into prodution for both the 76mm and 3in guns, the HVAP ammunition was used effectively during the final months of the war.
(In the section on 90mm gun experimentation) Although the upgunned (90mm) Sherman appeared to be a good solution o the problem of increased firepower, General holly wasinformed that it would be about 6 months (ie Dec 44) before produciton quantities could be available. By tha time the new Pershings woud be coming off the assembly lines so the decision was taken to drop the 90mm armed Sherman and to concentrate all efforts on speding up Pershing production. In retrospect, it appears the wise course would have been to procure some fo the 90mm armed Shermans as a hedge against further delays in the arrival of the Pershing. However, the real problem was the late hour when the decision was made in favor of a high powered tank gun. Production could not be turned on and off like a waer faucet, despite the seemingly miraculous performace that frequently was achieved. If need for a poweful tank gun had been specified a year earlier, they certainly could have been made available in time for the Normandy invasion. however, argument over the role of the tank still raged until evens on the battlefield proved conclusivey that tanks had to be able to fight tanks and that the best tank destroyer was a better tank.
As late as June 44, it was consiered that the 76mm gun tank would make up only one third of the armored strength with the balance retaining the 75. Within a month the hedgrow fighting had shown the 75 to be completely ineffective against the front armor of the german Panther and Tigers. The combat units now wanted every 76mm gun tank available. Earlier objections to excessive muzle blast and the long wkward rounds of ammunition were forgotten overnight, only hole punching ability was important. Even the 76 proved inadequate in this regard and the ush was on to obtain a weapon which could penetrate the front armor of the tough skinned enemy tanks.
In August a few rounds of the new 76mm HVAP (APCR) ammuntion were rushed to France and tests conducted near Isigny against six captured Panthers. The tests showed the new ammunition was extremely accurate and a great improvement over the old APC M62, but it could not penetrate the Panther's front plte at ranges over 300 yard. Production of the new ammunition was also limited to only 10,000 rounds per month, which meant that it could only be used on an emergency basis.
On 9 August 44, gen Omar Bradley directed his XII Army Group, Armor Section to request an allotment of tanks armed with the british 17lber. This attempt proved fuitless since the limied tnak reserves were insufficient o permit the release of vehicles for the installation of the British gun. The effort to obtain 17 lber tanks was revived laterin the middle of Feb 45 when reserve tank situation had impoved. At that time, the XII AG requested an initial conversion of 160 Shermans wih further conversiondependant on battel experience. Later this was cut to 80 becasue of limitations in British ammo supplies. Unfortunatley, the crowded condition of the shops delayed delivery and only the first few began to arrive in mid-March. These were allotted to the Ninth Army, but there is no recod of their use prior to the end of the war. In fact, the Ninth Army After Action Report indicates that the delievery of 40 17lber tanks was expected, but it does not record their arrival.
Interestingly, much of the delay getting the 76mm fielded was taken up problems identified by perhaps too much "listening to the gripes of troops on the ground". While in hindsight a singular focus on "hole-punching" while ignoring the other issues that may have prevented that capability from being effectively used was a Hobson's choice. Rushing the 76 out would likely have resulted in troops on the ground complaining about poor rate of fire, turret freezing in rough terrain, and inability to effectively taget after the first few rounds.
Is it better to have guns that can hit the target with marignal effectiveness or a gun that can penetrate, if you can get a hit, but for which that is a more difficult task? And given the problem was engaging enemy heavy tanks, where does the decision to abandon the M6 Heavy tank - a decision that implicitly accepted the risk of sending more medium tanks which could be assumed to find themselves up agaisnt enemy heavy tanks? Would it have been better, rather than using tank destroyers in independant battalions (later companies) or say attach a platoon of them to each tank company? By the time the answers were understood, the war would be over before they could be fielded. And one can't discount the fact that Sherman armored forces in North Africa and Italy wer nonetheless successful at driving the Germans back.
Was the Sherman perfect? Hardly, but neither were any of the other tanks its comparable to.
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What is the best book describing this ballistic issue? (In english).
World War II Ballistics: Armor and Gunnery by Lorrin Bird and Robert D. Livingston (Overmatch Press) but I believe it is out of print...
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RE: What is your favorite WWII tank? - 
) 
. The stopping of Market garden and the attempted stopping of Pattons rampage in lorraine might also qualify as "operational redeployment" of significant assets in the west (at least if we don´t count armour as the sole measuring stick of "operational redeployment). 
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