THE 76 MM GUN M1A1 AND M1A2: AN ANALYSIS OF U.S. ANTI TANK CAPABILITIES DURING WORLD WAR II

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Thoddy
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THE 76 MM GUN M1A1 AND M1A2: AN ANALYSIS OF U.S. ANTI TANK CAPABILITIES DURING WORLD WAR II

Post by Thoddy » 25 Jan 2018 14:31

New published publication at DTIC .mil

Accession Number : AD1045347
Title : THE 76-MM GUN M1A1 AND M1A2: AN ANALYSIS OF U.S. ANTI-TANK CAPABILITIES DURING WORLD WAR II
Descriptive Note : Technical Report,01 Jan 1939,31 Dec 1945
Corporate Author : ARDEC, METC, RDAR-MEM-M Picatinny Arsenal United States
Personal Author(s) : Cosme,Jose ; Ranu,Jeff ; Spickert-Fulton,Shawn
Full Text : http://www.dtic.mil/dtic/tr/fulltext/u2/1045347.pdf
Report Date : 01 Jan 2018

Pagination or Media Count : 58


Abstract : This report provides an analysis of the U.S. anti-tank technology during World War II. A ballistic analysis is used to corroborate the battlefield history and gain an understanding of the physical and technological factors that spurred the development of the M1 series 76-mm Gun and family of ammunition.The technical manual (TM) 9-1907 was published 23 September 1944, but it was missing performance data for the 76-mm hyper-velocity, armor-piercing (HVAP) shell and any information for performance of the U.S. anti-tank capabilities against the German Panther tank. Battle history indicates there was a technological capability gap against upgraded Panzer armor. This report attempts to use hand calculations and modeling and simulation (PRODAS) to fill in the information that is missing in TM 9-1907. The analysis offers the reader a greater engineering comprehension of the challenges faced between June 1944 and May 1945 and the circumstances necessitating the rapid fielding of the 76-mm HVAP shell after German capability upgrades were encountered in the European Theater of Operations from Normandy to the Battle of the Bulge (June to December 1944).
"Meine Herren, es kann ein siebenjähriger, es kann ein dreißigjähriger Krieg werden – und wehe dem, der zuerst die Lunte in das Pulverfaß schleudert!"

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Re: THE 76 MM GUN M1A1 AND M1A2: AN ANALYSIS OF U.S. ANTI TANK CAPABILITIES DURING WORLD WAR II

Post by Mobius » 31 Jan 2018 17:10

Nice Find Thoddy.
Interesting the US had 76mm Shermans before D-day but they were left in Britain. So only the M10s would be able to use HVAP until later in 1944.

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Re: THE 76 MM GUN M1A1 AND M1A2: AN ANALYSIS OF U.S. ANTI TANK CAPABILITIES DURING WORLD WAR II

Post by critical mass » 31 Jan 2018 23:07

The modelling methodology is flawed, to say the least.

To be honest, the authors use a black box approach, they feed in data, presume everything in the black box is ok, and readily extract the data to jump to further conclusions. One of the issues I have with these formula´s is that apparently no effort was spent by the authors to explore the limits of validity for each formula. I am not convinced that the authors are even aware that the Thompson & Lambert-Zukas formula is only valid for a single projectile & plate failure mechanism. An interaction , from which we know (by firing trials) does not hold true for the 75mm at the very least.

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Re: THE 76 MM GUN M1A1 AND M1A2: AN ANALYSIS OF U.S. ANTI TANK CAPABILITIES DURING WORLD WAR II

Post by Sheldrake » 31 Jan 2018 23:48

I take issue with this quote
The inability of the 3 in. and 76-mm to penetrate the frontal armor of the Panther sent a shockwave through allied command.
I think it may have sent a shockwave through American command. However, the British were aware of the limitations of the 3" and up gunned both the M4 tanks and M10s to carry the 17 Pounder. Furthermore, the British had already developed APDS ammunition for the 6 pdr (57mm). Anti tank gunners from at least one division attended a firepower demonstration that showed that this shot could penetrate the armour of a Panther.

The British and Canadians bore the brunt of the armoured battle in Normandy. I think the findings of this study need to be considered alongside OR study 17 (German AFV casualties) http://lmharchive.ca/wp-content/uploads ... Monty2.pdf

Look at table 4, which is mainly concerned with Pz V and PzVI. 38% of 75mm hits penetrated these big beasts. If there were enough M4s in good enough tactical positions it was possible take down panthers - as 4 AD did at Arracourt in September.

While there was a lot of criticism within the armoured corps about the inadequacy of British tanks, I can't find it among British anti tank gunners. One of the first SP casualties on D Day was Sgt Mitchley of 20 Atk Regt whose 3" M10 was in the line against the only German tank attack on D Day. On 8th July on Hill 112 Sgt Cummings of stalked a Tiger that had earlier knocked out four Churchills - reccing the route on foot first. Hill 112 was a seriously unhealthy place with little cover and opposing a battalion of Tiger tanks - real not misidentified Mk IVs.

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Re: THE 76 MM GUN M1A1 AND M1A2: AN ANALYSIS OF U.S. ANTI TANK CAPABILITIES DURING WORLD WAR II

Post by Mobius » 01 Feb 2018 00:36

Sheldrake wrote: Furthermore, the British had already developed APDS ammunition for the 6 pdr (57mm). Anti tank gunners from at least one division attended a firepower demonstration that showed that this shot could penetrate the armour of a Panther.
You mean 17 pdr APDS could penetrate the front of a Panther? The 6 pdr APDS could not from the front.

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Re: THE 76 MM GUN M1A1 AND M1A2: AN ANALYSIS OF U.S. ANTI TANK CAPABILITIES DURING WORLD WAR II

Post by Yoozername » 01 Feb 2018 04:18

It kind of comes off like a 'book report'.
The 75-mm gun is ineffective at point blank even against the front turret of the Pz IV E and is
only effective at close ranges against the side hull armor of the Panther. Captain Farmer’s
predicament recounted previously in this report becomes painfully clear.
Cpt. Farmer was a tank rammer.

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Re: THE 76 MM GUN M1A1 AND M1A2: AN ANALYSIS OF U.S. ANTI TANK CAPABILITIES DURING WORLD WAR II

Post by Richard Anderson » 01 Feb 2018 18:23

Mobius wrote:Nice Find Thoddy.
Interesting the US had 76mm Shermans before D-day but they were left in Britain. So only the M10s would be able to use HVAP until later in 1944.
It would not have mattered, since there were no HVAP 3" or 76mm projectiles available in Europe prior to late-August 1944. One of the consequences of the Shoeburyness test on 23 May was the realization that the American APC projectile design and manufacture was flawed. The result was a request from AGF to Ordnance for a crash program to solve the problem. Ordnance in turn had been working on hyper-velocity rounds since mid 1942, but had concentrated on HVAP discarding sabot rather than composite-rigid. The AGF request caused Ordnance to turn to the simpler APCR design (the APDS designs remained problematic) in June and after six weeks of hasty testing they were able to produce a small pre-production lot of about 1.000 76mm HVAP rounds produced in July, some of which was sent to France and used in the 2nd Isigny test, 19-21 August. The first 1,000-round production lot of 3" HVAP was completed then in August and was followed by the first production lot of 76mm in September. By August 1945, 63,000 rounds of 76mm and 33,000 rounds of 3" HVAP were completed, of which probably about 34,000 and 30,000 respectively reached Europe.
"Is all this pretentious pseudo intellectual citing of sources REALLY necessary? It gets in the way of a good, spirited debate, destroys the cadence." POD, 6 October 2018

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Re: THE 76 MM GUN M1A1 AND M1A2: AN ANALYSIS OF U.S. ANTI TANK CAPABILITIES DURING WORLD WAR II

Post by Richard Anderson » 01 Feb 2018 18:48

Yoozername wrote:It kind of comes off like a 'book report'.
The 75-mm gun is ineffective at point blank even against the front turret of the Pz IV E and is
only effective at close ranges against the side hull armor of the Panther. Captain Farmer’s
predicament recounted previously in this report becomes painfully clear.
Cpt. Farmer was a tank rammer.
It is also notable that in the actual account given by Hunnicutt that Cosme et al paraphrased there is no indication that the four rounds of HE and AP fired did not penetrate. "Sergeant Edward A. Rejrat...fired four 75mm HE and AP shells pointblank into the Panther. The explosions rocked the men in the Sherman, but as the dazed survivors of the Panther's crew tried to climb out of their tank, Captain Farmer shot them with a submachine gun." (Hunnicutt, Sherman, p. 312.)

Overall, I suspect the authors have a pretty good grasp of modelling techniques and wargaming literature on the subject, but for some reason despite where they work they made little or no use of the APG library archives or the Ordnance records at NARA. As I noted in an email to a friend who is a former Marine tanker, "they essentially got quite a bit backwards. The 76mm was originally designed for the Medium Tank M4, not the GMC T70, which originally was intended to mount the 57mm. The 76mm was required because the 3" M1 would not fit in the Medium Tank M4 as was originally planned. However, the debacle of the M4A1 (76M1) procurement and test in December 1942-January 1943 and Armor giving it a thumbs down meant the gun production was available just as the Tank Destroyers decided they wanted a bigger gun in the T70. On 3 January 1943, a committee of Ordnance, Armor, and TD agreed most of the initial 1,000 produced would go to the T70 program.

I am also not convinced that an additional 15" of barrel length could have generated anther 400 fps Mv in the 76mm without a substantial increase in propellant. How is it that the 17-pdr, with three times the propellant and just two calibers less length only managed to produce 3000 fps Mv?"

All in all a very odd document.
"Is all this pretentious pseudo intellectual citing of sources REALLY necessary? It gets in the way of a good, spirited debate, destroys the cadence." POD, 6 October 2018

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Re: THE 76 MM GUN M1A1 AND M1A2: AN ANALYSIS OF U.S. ANTI TANK CAPABILITIES DURING WORLD WAR II

Post by Mobius » 01 Feb 2018 20:38

The 17 pdr had a MV of 2900 f/s and a length of 55 calibers. The 77mm had a length of 52 calibers and a MV 0f 2575 f/s.
http://www.wwiiequipment.com/index.php? ... &Itemid=58

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Re: THE 76 MM GUN M1A1 AND M1A2: AN ANALYSIS OF U.S. ANTI TANK CAPABILITIES DURING WORLD WAR II

Post by Richard Anderson » 01 Feb 2018 21:42

Mobius wrote:The 17 pdr had a MV of 2900 f/s and a length of 55 calibers. The 77mm had a length of 52 calibers and a MV 0f 2575 f/s.
http://www.wwiiequipment.com/index.php? ... &Itemid=58
Indeed. And the 3" and 76mm M62A1 APC fired from the 3" 50 caliber Gun and 76mm 52 caliber Gun generated a Mv of 2600 fps. The 76mm did it with 3.62 pounds of FNH propellant, the 3" with 4.62 pounds of NH propellant, and the 17-pdr with 9 pounds of propellant. I do not see how increasing the 76mm by three calibers to 55 without increasing the propellant would somehow give it 300 fps greater Mv from the M62A1, matching the 17-pdr. Or how the same would somehow generate 400 fps greater Mv from the T4E16 HVAP.
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Re: THE 76 MM GUN M1A1 AND M1A2: AN ANALYSIS OF U.S. ANTI TANK CAPABILITIES DURING WORLD WAR II

Post by Sheldrake » 02 Feb 2018 00:06

Mobius wrote:
Sheldrake wrote: Furthermore, the British had already developed APDS ammunition for the 6 pdr (57mm). Anti tank gunners from at least one division attended a firepower demonstration that showed that this shot could penetrate the armour of a Panther.
You mean 17 pdr APDS could penetrate the front of a Panther? The 6 pdr APDS could not from the front.
I think the gunners of the time thought the 17 Pdr APCBC could penetrate from any angle. Table 4 in OR 17 lists 21 penetrations out of 25 hits against Pz V & PzVI and only four failures.

However, the OR study also concluded that hits were no more likely on the front than on the side. The disproportionate heavy frontal armour on the Panther left the sides dangerously vulnerable in the close country of Normandy.

The British may have been dangerously confident but PRO document WO291/171,
OR report on effectiveness of British anti-tank guns, 1943.
Ranges in yards, armour as detailed in notes.
6 pdr AP on Tiger I
Exposure Success % 0º 45º 90º 135º 180º
Full view 90 % - - - - -
50 % - - 1200 - 1000
30 % 650 650 1350 500 (missing)
Hull down 90 % - - - - -
50 % 300 - 500 - -
30 % 650 200 850 550 650
6 pdr APCBC on Tiger I
Exposure Success % 0º 45º 90º 135º 180º
Full view 90 % - - 700 - -
50 % 500 - 1650 500 1650
30 % 750 650 2100 350 1350
Hull down 90 % - - - - -
50 % 300 - 500 - -
30 % 650 200 900 550 650
17 pdr AP on Tiger I
Exposure Success % 0º 45º 90º 135º 180º
Full view 90 % - - 700 - 500
50 % 1750 700 2050 600 1950
30 % 1850 1450 2600 1600 2500
Hull down 90 % - - - - -
50 % 750 - 800 600 -
30 % 1300 550 1200 1000 800
17 pdr APCBC on Tiger I
Exposure Success % 0º 45º 90º 135º 180º
Full view 90 % - - 900 - 550
50 % 2000 600 2300 650 2050
30 % 2700 1300 2850 1750 2850
Hull down 90 % - - - - -
50 % 700 50 750 650 -
30 % 1300 450 1250 1050 850
6 pdr AP on Panther
Exposure Success % 0º 45º 90º 135º 180º
Full view 90 % - - 750 - 900
50 % 50 800 1350 800 1200
30 % 100 1200 1800 1200 1800
Hull down 90 % - 100 100 50 50
50 % - 300 850 300 800
30 % 50 700 1150 800 850
6 pdr APCBC on Panther
Exposure Success % 0º 45º 90º 135º 180º
Full view 90 % - - 850 - 1150
50 % 50 750 1650 1000 1450
30 % 100 1500 2200 1400 1950
Hull down 90 % - 50 50 50 50
50 % - 250 850 250 850
30 % 50 800 1150 850 1150
17 pdr AP on Panther
Exposure Success % 0º 45º 90º 135º 180º
Full view 90 % - - 1250 1200 1100
50 % 50 1800 2350 2000 2100
30 % 100 2150 2850 2550 2750
Hull down 90 % - - 300 400 350
50 % 450 550 1000 1150 1100
30 % 650 1150 1750 1750 1800
17 pdr APCBC on Panther
Exposure Success % 0º 45º 90º 135º 180º
Full view 90 % - - 1200 1250 1200
50 % 50 1750 2350 2350 2250
30 % 100 2550 2900 2850 2850
Hull down 90 % - - 400 500 450
50 % 300 550 1100 1200 1100

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Re: THE 76 MM GUN M1A1 AND M1A2: AN ANALYSIS OF U.S. ANTI TANK CAPABILITIES DURING WORLD WAR II

Post by Mobius » 02 Feb 2018 00:24

Here is an actual British test on the Panther.
https://photos.google.com/share/AF1QipP ... JZNWJfdS1R
There is one out there on the Tiger as well.

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Re: THE 76 MM GUN M1A1 AND M1A2: AN ANALYSIS OF U.S. ANTI TANK CAPABILITIES DURING WORLD WAR II

Post by Sheldrake » 02 Feb 2018 01:06

Mobius wrote:Here is an actual British test on the Panther.
https://photos.google.com/share/AF1QipP ... JZNWJfdS1R
There is one out there on the Tiger as well.
Interesting. The conclusions are that in theory the 17 pdr AP and APCBC should not penetrate the glacis, but the manufacturing quality of the armour was lower than comparable British manufacture. Its also worth noting that 6Pdr APBC and APDS penetrated the mantlet and a hit pon the lower mantlet would be likely to penetrate the hull roof and ammunition bin and cause a cordite fire.

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Re: THE 76 MM GUN M1A1 AND M1A2: AN ANALYSIS OF U.S. ANTI TANK CAPABILITIES DURING WORLD WAR II

Post by Mobius » 02 Feb 2018 01:51

Sheldrake wrote: Its also worth noting that 6Pdr APBC and APDS penetrated the mantlet and a hit pon the lower mantlet would be likely to penetrate the hull roof and ammunition bin and cause a cordite fire.
You'll have to point out which 6Pdr penetrated the mantlet on a fair hit. One penetrated through the gun sight.

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Re: THE 76 MM GUN M1A1 AND M1A2: AN ANALYSIS OF U.S. ANTI TANK CAPABILITIES DURING WORLD WAR II

Post by Michael Kenny » 02 Feb 2018 02:43

That is a test conducted on 2 Panthers from Normandy. 1 complete Panther and the hull from a second Panther which had the turret from a third-a Frankenpanther!

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