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

[Richard Anderson]

I posted primary sources. Explain how the US data is 'better'? Do you know what a primary source is? Do you know what data is?

By "better" he may have simply meant he could read it.

[Yoozername]

It did have more pictures...

[Yoozername]

The Soviet projectile was also lighter. ~6.5Kg

[Yoozername]

I thought this report had been brought up in this thread but maybe it was in the 'KWK 40/Pak 40' thread. If anything, it should be brought up in the pseudo-report in theOP.

http://www.dtic.mil/dtic/tr/fulltext/u2/492002.pdf

In any case, given the date of around early 1944, the US did seem concerned regarding how to 'hang' armor. That is, thickness, quality and slope being the investigation. Given that tank development had chosen a path already, it seems a little late to the party. But, I digress, it is a great study and features the threat level posed by German 7,5 cm Pzgr 39 weapons. It might be a tough read for some, but one of the (inferred) conclusions, when comparing the US M62 type AP and German 7,5 cm Pzgr 39 is that the US should investigate using a similar projectile!

The main theme is always that "the projectile is the weapon, not the 'gun'". The US weapons were making good velocities, but the manufacturing, and the design itself was clearly inferior to the German types (ammunition-wise).

[Richard Anderson]

I thought this report had been brought up in this thread but maybe it was in the 'KWK 40/Pak 40' thread. If anything, it should be brought up in the pseudo-report in teh OP.

http://www.dtic.mil/dtic/tr/fulltext/u2/492002.pdf

In any case, given the date of around early 1944, the US did seem concerned regarding how to 'hang' armor. That is, thickness, quality and slope being the investigation. Given that tank development had chosen a path already, it seems a little late to the party. But, I digress, it is a great study and features the threat level posed by German 7,5 cm Pzgr 39 weapons. It might be a tough read for some, but one of the conclusions, when comparing the US M62 type AP and German 7,5 cm Pzgr 39 is that the US should investigate using a similar projectile!

The main theme is always that "the projectile is the weapon, not the 'gun'". The US weapons were making good velocities, but the manufacturing, and the design itself was clearly inferior to the German types.

ADA954805, M. Bolotsky, Historical Review of the Correlation of Ballistic and Metallurgical Characteristics of Domestic Armor at Watertown Arsenal,WAL710/795 from 7 December 1945 is also valuable for understanding the state of the art as it was practiced by US Army Ordnance at the end of the war. Earlier reports are Col. H. H. Zornig, An Analysis of Firings of Rolled Homogenous Armor, Report Number WAL 710/493, ((Watertown, N.Y.: Watertwon Arsenal Laboratory, 15 October 1943) and Col. H. H. Zornig and Maj. N. A. Matthews, Armor Plate Ballistic Testing Object, Report Number WAL 710/685, (Watertown, N.Y.: Watertown Arsenal Laboratory, 2 August 1943).

[Nick the Noodle]

The 76mm M1 has always fascinated me. It was never a really decent gun in WW2, but obviously the right direction to go, considering Korea. It was nowhere as capable as the 17pdr vs armour, nor even the 77mm, but outlived both as far as the main armament of a medium tank was concerned.

The 76mm was unwanted prior to D-Day, for a shed load of reasons posters here will know, and yet suddenly desired when a Normandy 44 tank rich environment was fought over. It was then found mainly unnecessary until 'The Bulge', when the 75mm M3 was found wanting. This led to NY Times articles Jan and Mar 45, and the Washington Post article also in Mar 45, which led to the (infamous) White Report.

What I find interesting is that the required 'best' weapon system changes with its environment, and the 76mm proves that there was no absolute best gun in WW2.

[Yoozername]

Maybe you should start threads expressing your feelings regarding all kinds of weapons? Since you have not read this thread either, why waste such great writing here....? (and since it barely reflects the conversation taking place?)

[Richard Anderson]

Oh dear God... :roll:

The 76mm M1 has always fascinated me. It was never a really decent gun in WW2, but obviously the right direction to go, considering Korea. It was nowhere as capable as the 17pdr vs armour, nor even the 77mm, but outlived both as far as the main armament of a medium tank was concerned.

As a "gun", i.e. the thingy that projectiles come out of, it was just fine. It's performance was not much different for what you want guns to do than that of the 17-pdr or PaK40.

On the other hand, its projectiles were problematic and bureaucratic decisions by Ordnance on barrel longevity meant it utilized less propellent and generated less Mv than some of its contemporaries, but that is quite a different thing.

I am curious why you think that it "outlived" the others as the main armament of a medium tank is important? It did so more because of the longevity of the tank it was in than for any other reason...the Medium Tank M4 was the only tank (other than the T20, T22, and T23) that it was ever used in.

The 76mm was unwanted prior to D-Day, for a shed load of reasons posters here will know,

Really? It was "unwanted prior to D-Day"? I did not know that, so please illuminate me.

and yet suddenly desired when a Normandy 44 tank rich environment was fought over.

It was? Again, please illuminate me as to this "sudden desire". I'm fascinated to hear about it.

It was then found mainly unnecessary until 'The Bulge', when the 75mm M3 was found wanting.

Wow! A trifecta! Please, I am all ears, do go on...

This led to NY Times articles Jan and Mar 45, and the Washington Post article also in Mar 45, which led to the (infamous) White Report.

The "White Report"? Really? Was that like a Super Secret Squirrel Double-Classified Congressional Report or something? And these newspaper articles led to it and it became infamous? Wow. Again, I'm all ears...no, sorry, I can't keep it up. I.D. White's LETTER (Ike specifically told the commanders he wrote to not to respond with a "General staff study"...White ignored him) was in response to Ike's query of 18 March to both I.D. White, CG 2d AD and Maurice Rose, CG 3d AD. White's response was a digest of anecdotes. Rose's was shorter and more to the point.

Hanson Baldwin's articles that started the controversy were published 3, 4, and 5 January, but he began fishing on the subject on 4 December. He then followed those with two more articles on 5 and 6 February, which finally excited Marshall's interest, who then queried Ike, who then queried White and Rose.

The Washington Post editorial of 22 March occurred before the Ike received White's letter and before he forwarded it to Marshall, so I don't think it could have led to it. All of this focused its criticisms on the Medium Tank M4 rather than its gun. White's remark in his cover letter about the 76mm was "The 76-mm gun is reasonably satisfactory, provided sufficient HVAP ammunition were available. If it were possible to design and substitute a long barrel piece with muzzle brake and approximately 3400-3500 feet per second muzzle velocity, similar to the German 75-mm HV tank gun, this tank would be equal to anything our enemies have to offer."

What I find interesting is that the required 'best' weapon system changes with its environment, and the 76mm proves that there was no absolute best gun in WW2.

Well, yes...

[Yoozername]

The 76mm M1 has always fascinated me. It was never a really decent gun in WW2, but obviously the right direction to go, considering Korea. It was nowhere as capable as the 17pdr vs armour, nor even the 77mm, but outlived both as far as the main armament of a medium tank was concerned.

He is so awfully funny..."considering Korea"... I wonder what he thinks he means...

The 76mm was as good or as bad as the 3 inch since they fired the same projectile at the same velocity. So neither one was the goodest or the baddest as measured in Nicky-Logic-Land. A place where 'shed-loads' of reasons are contained. And weapons change somehow with their 'environment'. I Like to see some of that data myself. Maybe it's in one of those sheds in Nicky-Logic-Land?

[Sheldrake]

The 76mm M1 has always fascinated me. It was never a really decent gun in WW2, but obviously the right direction to go, considering Korea. It was nowhere as capable as the 17pdr vs armour, nor even the 77mm, but outlived both as far as the main armament of a medium tank was concerned.

The 76mm was unwanted prior to D-Day, for a shed load of reasons posters here will know, and yet suddenly desired when a Normandy 44 tank rich environment was fought over. It was then found mainly unnecessary until 'The Bulge', when the 75mm M3 was found wanting. This led to NY Times articles Jan and Mar 45, and the Washington Post article also in Mar 45, which led to the (infamous) White Report.

What I find interesting is that the required 'best' weapon system changes with its environment, and the 76mm proves that there was no absolute best gun in WW2.

A couple of observations

#1 As far as I am aware, the proportion of 76mm equipped M4s rose from D Day to the Bulge. The 75mm M4 was retained because it had a better HE round. The Germans had more anti-tank guns, machien guns and panzerfausts than tanks. Tanks in NWEurope spent more time engaging anti tank guns and supporting the infantry than killing tanks.

#2 The 17 pounder disappeared because the British developed better tank guns. The 20 pdr followed by the 105mm that equipped the Centurion was a much better gun and adopted as the initial armament for the M1 Abrams, as well as the leopard I. The longevity of the 76mm is solely due to the survival of so many M4 in tanks used by second rate armies.

[Yoozername]

Technically, the US did pursue the 76mm class weapon further with the Walker Bulldog. This never made it to Korea, but it was fielded afterwards. While designed as a light tank, a replacement for the M24, its improved ammunition kept it viable till the Soviets fielded the masses of T54/55.

As great as most online warriors will tell you the 'Firefly' was, it was actually stuffing a larger gun than the 3 in. into a turret that could not fit a 76mm. The T23 turret was needed for the 76mm. While the 17 pdr. gave good AT service, it is very cramped and given the even larger ammunition than the 3in/76mm, then I think most (rational) people that view this video would appreciate the conditions.

https://www.youtube.com/watch?v=__Y8YJeas4I

[Richard Anderson]

A couple of observations

Excellent as always.

#1 As far as I am aware, the proportion of 76mm equipped M4s rose from D Day to the Bulge. The 75mm M4 was retained because it had a better HE round. The Germans had more anti-tank guns, machien guns and panzerfausts than tanks. Tanks in NWEurope spent more time engaging anti tank guns and supporting the infantry than killing tanks.

Indeed, from 0% on D-Day, to 9.97% on 21 July 1944, to 28.58% on 15 December 1944, to 53.37% on 5 May 1945.

The "reason" it was retained is usually attributed to the "better HE round" but also had about as much to do with indecision on the part of the American Armored Force in 1942-1943, failures of the Ordnance Department in the same time frame, and the desire by the British to keep production of a tank convertible to the 17-pdr role. Plus simply bureaucratic inertia and the necessary industrial inertia in tooling from one design to a very different one.

#2 The 17 pounder disappeared because the British developed better tank guns. The 20 pdr followed by the 105mm that equipped the Centurion was a much better gun and adopted as the initial armament for the M1 Abrams, as well as the leopard I. The longevity of the 76mm is solely due to the survival of so many M4 in tanks used by second rate armies.

Or first rate armies in at least one case...I would say the real reason for the longevity of the Medium Tank M4 and the T34 as well was the sheer number produced in excess of the immediate requirement linked to their general mechanical reliability, which made them excellent candidates to dump on...sorry, transfer to allies and prospective client states.

[Mobius]

Here is a graph I made comparing 76mm M62 vs. face hard and homogeneous armor. And 90mm M82 vs. the same.
(0° striking angle)

[Yoozername]

Both the M62 and M82 designs should perform better against FHA, but did the US really have 5 inch FHA sitting at 2500 yards away from the 90mm during a test? I suppose that almost all tank armor by the later years in WWII was homogenous? Actually, castings were being used for thicker armor?

If that data is 'true', then the 76mm should have had no issues taking on Tiger Is at 1000-1500 yards?

[critical mass]

Notice that the data is a best fit curve for US trial data on US homogenious RHA armor. The latter is softer -in average- than contemporary german RHA and intends to always fail by ductile hole formation. While the effect of hardness difference itselfe is a rather mild one at 0° -30° obliquity when the projectile stays intact, one need to keep in mind that it will have a profound impact on the ability of the projectile to stay intact at elevated velocities (= short range), particularely if the projectile is of inferior quality such as M82 and M62. If the projectile breaks up, more of the energy usually expanded in ductile hole formation is spread out on the plate and this raises the critical velocity and consequently reduces penetration. Complete shatter will reduce penetration by approx. 1/3 compared to intact projectiles at normal impact obliquity.