"SABOT round for US 57mm in Normandy" Topic

Some sources and some war gamers/historians claim that the US 57mm did not use the APDS (armour-piercing discarding sabot) in late WW2 despite its use by the British from June 6 onwards in the six-pounder/57mm and the issue (about a month later) of a 17-pounder APDS round.

The effect of sabot is to greatly increase the armour-piercing capability of the gun. The six-pounder's went up from about 80mm to about 150mm. The British Tyneside Scottish battalion found it highly effective at Rauray once they stopped shooting too high.

Cruising some US WW2 footage on YouTube just today I found this:

YouTube link

Dated early August 1944 look in the first minute of footage, at the US 57mm gun crew and the ammunition they are passing forward. Rounds two and four are clearly sabot rounds as you can see the step where the sabot petals meet the AP core.

Previously I had found on-line accounts that US 57mm used the sabot round during the Battle of the Bulge but it is unclear how the rounds were obtained as the US never manufactured sabot during the war, preferring the less effective US APCR.

It would appear that – as early as August 8 1944 – the US HAD obtained stocks of British APDS.

A hoary old story was that the US guns 'could not fire APDS as the twist of their rifling did not match the British guns'. Given that some 'British' six-pounders were actually manufactured in the US I think this film footage puts the lie to that story. Yes the US gun had access to British manufactured ammunition and yes the US gun COULD fire that ammunition.

Barry

Cruising some US WW2 footage on YouTube just today I found this:

YouTube link

Dated early August 1944 look in the first minute of footage, at the US 57mm gun crew and the ammunition they are passing forward. Rounds two and four are clearly sabot rounds as you can see the step where the sabot petals meet the AP core.

Quite agree. Rounds 2 and 4 are clearly Sabot rounds.

Some sources and some war gamers/historians claim that the US 57mm did not use the APDS (armour-piercing discarding sabot) in late WW2 despite its use by the British from June 6 onwards in the six-pounder/57mm and the issue (about a month later) of a 17-pounder APDS round.
…
Previously I had found on-line accounts that US 57mm used the sabot round during the Battle of the Bulge but it is unclear how the rounds were obtained as the US never manufactured sabot during the war, preferring the less effective US APCR.

The US Army did not provide Sabot rounds for the 57mm gun.

That does not mean British rounds would not work. It only means that a US crew who had Sabot rounds got them from the British supply lines, not the US supply lines.

British APDS 57mm rounds were test-fired in US 57mm guns on several occasions. The desperately poor accuracy caused the US Army to look other ways for increasing penetration. Many excuses were offered in the test firings for the exceedingly poor accuracy of British APDS rounds, but in truth most British WO test firings showed equivalent accuracy to the US test firings. The British army was simply more willing to accept ammunition that could hardly hit the broad side of a barn if that ammunition had better odds of penetrating that barn once hit.

The effect of sabot is to greatly increase the armour-piercing capability of the gun.

APDS has no necessary advantage over APCR at short to medium ranges. Both are very light rounds for the caliber of the gun, and so start with very high initial velocity. Both have very hard metal cores (typically Tungsten), and so can use their velocity well to penetrate armor. APDS has an technical edge over APCR once you get to longer ranges, as it discards the light weight full-caliber wrapper around the core, and with the resulting change in diameter-to-mass ratio has lower wind resistance and so retains it's initial high velocity better over distance.

That was irrelevant in WW2, as British APDS was unable to hit a target at longer ranges. So who cares that it's going faster as it flies off to the horizon?

Some examples of WW2 era APDS accuracy:

First, from the British perspective …

WO 291/751 AORG Memo No.427, 24th Nov 1944, "Comparative Dispersion of Tank Guns"

Probability of a hit when firing for effect on a target 2' high by 5' wide (M.P.I. assumed on centre of target)
@ (yards) ……….…………………… 500yds; 800; 1000; 1500:
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%

Please note that the British fired 90 rounds of 6pdr APDS, and scored only 50% hits on a tank turret sized target at 800 yards range. And that is ON A RANGE, with no ranging errors and no combat stresses.

When the British fired US 76mm APC ammo at that same distance, they scored 100% hits.

The British 17pdr APDS scored even worse, hitting less than 50% of the time at 500 yards! At 800 yards it scores 21 percent chance of a hit! Again, that's on a range, without stress, when the distance is perfectly known.

In a post-war US Army Ordnance test of the Sherman Firefly firing APDS conducted postwar in 1946, comparative results were sought firing at a 6" thick test plate that was 5.5ft wide by 4.5ft tall, setback at 30 degrees. At a range of 1,050 yards the testers were able to achieve only two hits, one of which had such shallow and wide strike that it was concluded to have been a side-slap of a ricochet from striking the ground in front of the target. After firing 38 rounds at the target, the Ordnance team went off to do something more productive with their time.

This was effectively a repeat of the US wartime testing, where you can see in excuses of the "official language" the frustration of the testers, who were ordered to publish comparative results but could not manage to enough hits on the targets to draw useful conclusions, even when they had experienced British gun crews do the firing for them.

A hoary old story was that the US guns 'could not fire APDS as the twist of their rifling did not match the British guns'.

I don't know much about that hoary old story, but it is true that the rifling in US guns was not optimized for sub-caliber rounds. But then, neither was the rifling in British guns. Which was one of the contributing factors to the abysmal accuracy of British APDS during WW2.

The US continued to reject APDS throughout the late 1940s and 1950s. The US never provided an APDS round for the 90mm guns that armed US MBTs in the M46, M47 or M48 series. US HVAP rounds (the US Army Ordnance designation for what the Brits called APCR) continued to provide every bit as much penetrating power as British APDS at short to medium ranges, with pin-point accuracy, while the US Army preferred HEAT rounds for long range engagements.

The British did resolve the accuracy of their APDS rounds, and later British tank guns, including later marks of the 20pdr gun, were in fact rifled specifically for APDS as their standard AP round. When the US adopted the British L7 gun as the 105mm M68 for use in the M60 tank (and later upgraded versions of the M48), the issues of 1944 had been resolved, and the technical superiority of APDS ammunition were clear enough that US Army Ordnance changed it's conclusion and wholeheartedly adopted the round.

But we should not let the post-1960 experience with APDS drive our understanding of the 1944 experience with APDS. There can be little doubt that British wartime APDS was very capable in armor penetration. But it was also a round that could miss the ocean from a boat. British priorities meant that it came into service, and those who used it spoke highly of it's penetration. Those who used US HVAP spoke highly of it's accuracy.

That said, initial US HVAP did have some difficulty with ricochets from highly sloped plates. I believe (never seen conclusive analysis, so just a belief) that this was due to the "shoulder" that these rounds retained. If the shoulder struck the armor before the point of the core, it may have initiated side-forces to encourage a bounce. These were resolved in the various sub-types of HVAP rounds that became available in the very last months of the war.

Also, the US was FAR behind on producing and supplying HVAP during WW2. Of that there can be little doubt. None of the initial production requirements were met. The rounds were far too slow to come into widespread availability.

Doesn't mean that APDS was somehow a magic silver bullet. Nor even a better round in the WW2 timeframe.

But certainly the British gun crew with APDS was happier than the US gun crew who had heard of HVAP but didn't have any.

-Mark
(aka: Mk 1)

acording to dick taylors book 'firing now',
(well worth getting), the usa had got hold of some british apds ammo in late autumn 44.
they also had to scrounge he from the brtitish in normandy.
all 6 pdr ammo was interchangable either us or gb made.

I think I would be of the same view as the British. A round that misses a lot but does damage when it hits has to be better than a non-APDS 6-pounder round that does no damage whether it hits or not.

The 17-pounder barely seems to need APDS.

The 17-pounder barely seems to need APDS.

Indeed. Depending on what penetration tables you take as gospel the 17pdr APCBC performs almost as well as the US 76mm HVAP.

Which was one of the contributing factors to the abysmal accuracy of British APDS during WW2.

I thought the major issue initially was uneven separation of the sabot petals, which was sorted before the end of the war. Rifling optimised for sabot rounds came later and brought the accuracy up to standard APCBC rounds. Of course smooth bore guns and fin stabilised rounds are the modern solution, apart from the Brits who stuck with the rifled guns so they can use HESH.

Indeed. Depending on what penetration tables you take as gospel the 17pdr APCBC performs almost as well as the US 76mm HVAP.

Or actually better. This is the conclusion from the US army's trials conducted in August ‘44 against the Panther.
"d. The 17pdr APCBC is more effective against the front of a Panther tank than is the 76mm HVAP, T4. Its margin of superiority is not great. Neither one can be depended upon to penetrate the glacis plate in one fair hit on average quality plate."
The standard 76mm M62 ammo was considered inadequate.
"b. That the 76mm APC, M62 is considered an unsatisfactory ammunition for use against heavy armor because of its inferior penetration."
No wonder US tanks crews wanted to barter for HVAP rounds.

If Americans admitted the foreign round was better, it must have been miles better.

I thought the major issue initially was uneven separation of the sabot petals, which was sorted before the end of the war. Rifling optimised for sabot rounds came later and brought the accuracy up to standard APCBC rounds.

Fred, my impression is that there were several factors, and the onion was pealed more-or-less one at a time.

I believe the factors were:

1) Gun sights. Initially there were no separate settings on the British guns for the APDS ammo. At any reasonable range, following the range settings for the standard rounds would put the APDS over the target.

2) Separate of sabot petals -- as per your description.

3) Rifling. The issue is the L/D ratio (length to diameter) of the projectile. A 40mm core has a different D than a 76mm full-bore AP round, but about the same L. When the L/D ratio changes, the rifling needs to change too, if you want to keep it stable in flight. But then you have rifling that is sub-optimal for full-bore rounds (like your APC, HE or HESH).

4) Muzzle brake. The muzzle brake on the 17pdr seems to have exacerbated the separation issue (or maybe just the stability issue). You may notice that the 20pdr and the 105mm L7 did not have muzzle brakes. In fact muzzle brakes disappeared from DS-firing guns in post-war developments.

To be fair, this is my impression. I do not claim to have the revealed wisdom on all matters sabot. I am but a lowly student of gunnery, not a professor.

This is the conclusion from the US army's trials conducted in August ‘44 against the Panther.

There were several tests. The one you quote is the US 12th Army tests at Issigny.

More from those test results (No words added or changed, but portions of the text removed for brevity. -Mk1):

4. Results of Test
a. A tabulation of the detailed results, with photographs, is attached as Appendix A1.
b. Accuracy
(1) A tabulation does not present a true picture of the comparative accuracy of the various ammunitions. With all the standard rounds, except 17pdr SABOT, the accuracy was such as to warrant attempting to hit specific parts of the front plates. In general this was successful, but some rounds fired at the lower glacis struck the upper nose, and vice versa. In addition, it was not possible to position all the tanks so that the nose was not, at least partially, hidden by the ground line. Therefore, it is felt that a better measure of accuracy can be obtained by considering the nose and glacis as one target.

Note the early call-out of 17pdr APDS accuracy.

(2) On this basis all twenty-two (22) rounds of 76mm HVAP, T4, and all twenty-three (23) rounds of 17pdr APCBC hit the target. … Forty-two (42) rounds of 17pdr SABOT were fired and only 57% [24 rounds] were hits. …

Note that they fired twice as many rounds of 17pdr APDS, because they were having a heck of a time hitting their targets.

Of note as we proceed -- the testers took pains to identify "fair hits", because rounds that strike weld seams or MG ball mounts, or skip off the edge of a plate, may well happen in combat, but should not be used as a basis of comparison with rounds that strike main plate full-on. Also, the testers perceived variances in the quality of the metal in the various Panthers they tested against, so they tracked their results not just by the ammunition used, but also by the quality of the plates on the tanks they were targetting.

c. Penetration
(1) At 600 yards, 17pdr APCBC penetrated the lower nose of tank No.1 (average plate), while 76mm HVAP failed to penetrate.
(2) At 400 yards, one round out of four fair hits of 17pdr SABOT penetrated the glacis of tank No.2 (best plate). This was the only penetration of this plate by a fair hit with any of the ammunitions (including 76mm HVAP w/17pdr APBC propellant, 76mm HVAP w/17pdr SABOT propellant) at ranges 200 yards and over.

(3) At 400 yards, one round out of one fair hit with 17pdr APCBC and one round out of one hit with 17pdr SABOT penetrated the lower nose of tank No.2 (best plate). Both rounds of 76mm APC, M62 failed to penetrate, and one round of 76mm HVAP penetrated while the second round failed to penetrate. …

Lower nose was a bit more vulnerable than glacis, but in truth presented a poor aiming choice except at very close ranges. Even on the test range, they found it hard to shoot at the lower nose on all the tanks.

(4) At 200 yards one fair hit with each of the standard ammunitions failed to penetrate the glacis of tank No.2 (best plate). The relative depths of the partial penetrations at this range were as follows:
(a) 17pdr APCBC – 2"
(b) 17pdr SABOT – 1 7/8"
(c) 76mm HVAP – 1 5/16"
(d) 76mm APC, M62 – 1"

(5) At 200 yards firing at the glacis of tank No.3 (average plate) one round out of four fair hits with 76mm HVAP penetrated, this round, after partially penetrating, …[illegible word]… and penetrated the plate …[illegible word]… . One round of 17pdr SABOT penetrated and one round failed to penetrate at this range. One fair hit with 17pdr APCBC failed to penetrate, but cracked the plate. The second round striking within 6" of the first round penetrated.

Cracked plate is notably less durable than whole plate. So the second round should not be considered a "fair hit".

The US Army testers, dismayed by the abysmal accuracy of the 17pdr APDS rounds, went through some fair logical gymnastics to try to explain it away…

(6) In contrast to the results obtained in this teast with 17pdr SABOT, in firing conducted by First U.S. Army at Balleroy on 10 July 44, 5 rounds were fired at the front plate of a Panther tank at 700 yards. Examination of pictures of this firing indicates that the first round struck the mantlet, the second between the track and the nose plate, the third at the junction of the nose and glacis and penetrated. The fourth and fifth were fair hits on the glacis and both penetrated. The conflict between these results and those obtained by the board is expalined by Col. A. G. Cole, Deputy Director of Artillery, Ministry of Supply. Col. Cole witnessed part of the test and states that the ammunition lot furnished the board had not been proof fired. He further states that, in his opinion, the lot is of sub-standard manufacture and if proof fired would not have been accepted.

I would note that the Balleroy results of 2 or 3 fair hits out of 5 shots at the glacis was not so much notably better than the Issigny results that a whole lot of explanation was in order.

It is fair to say that there might be manufacturing variances, or that sub-standard ammunition might have fallen into the hands of the testers. But this was a test conducted IN THE COMBAT ZONE. Where and how did they come by this ammunition if it was sub-standard?

Included in the description of the testing methodology was this reference to who did the shooting:

3. Nature of Test
…
f. The 17pdr guns were fired by two superior British enlisted gunners. The 76mm gun was fired by two officers with considerable test firing experience.

So the accuracy issue should not be put down to Americans firing British guns, neither over national prejudice or simple unfamiliarity.

If Americans admitted the foreign round was better, it must have been miles better.

4thC: While this perspective might be reasonable based on bar room brag sessions, I think it is a bit short-sighted to suggest it as national policy, even within the US Army and Army Ordnance hierarchies.

Consider, for example:

- The US M1903 Springfield rifle was based on a German Mauser action (licensed for production and further development)

- The Vertical Volute Spring (VVS) suspension System of the US M2, M3 and M4 medium tanks was based on a French design, chosen in preference to US home-grown solutions such as the Christie suspension.

- The US 75mm field guns of the inter-war and early WW2 era, just being replaced by the 105mm howitzer when US forced landed in French North Africa, was a licensed copy (with minor further developments) of the French 75mm M1897 gun. This was also the gun that was mounted in the first US Tank Destroyers to see action (the M3 TDs).

- The US 155mm gun was also based on a French gun.

- The US "Pineapple" hand grenade was based on a French grenade.

- The USMC adopted the .55 Boys AT rifle (oh my now THAT was a gem!) for its Raider battalions.

- The US Army adopted the British 6pdr AT gun (with minor adjustments) for its upgrade from the US-designed 37mm AT gun.

- The major production versions of the US Army Air Corps' premier fighter, the P-51, were powered by license-built Rolls Royce Merlin engines.

- The USN adopted British-designed ASDIC (called SONAR in the USN).

I think it is rather unfair to suggest that the US military was not willing to approach foreign designs and foreign technology with a reasonably open mind. Yes, there was surely some bureaucratic inertia on any given issue, but that was true even if it was a domestic technology.

At least that is my reading.

-Mark
(aka: Mk 1)

@ Mark

Fair comments and I wasn't being entirely serious. I do wonder though why the US never put a licensed copy of the 17-pounder into production, unless it was because, by the time they accepted they were going to be needing it, it was too late.

Britain seems to have been quite forward-thinking in this area. The 6-pounder was delayed by Dunkirk but otherwise would have been right along just in time, while 17-pounders turned up in North Africa right when Tigers did. So the weight of AP round fired tripled from 2 to 6 pounds then tripled again to 17 pounds, all inside 3 years.

@4th I think by the time they thought they needed it they already had the 90mm in the pipeline and it made sense to go with that. Given that they were already producing 90mm tubes and had the tooling ready to go.
@Mark The interesting thing, to me, about the Isigny tests, which I hadn't appreciated before was that in real world tests the 17pdr APCBC had a slight edge over the 76mm HVAP. Given the rarity of HVAP that makes the Firefly a better tank going up against the German cats than the 76mm. A fact which "The Chieftain" glosses over in his myth busting video youtu.be/bNjp_4jY8pY
Comparing the performance of a rare special round to that produced by a plentiful standard round is not a fair comparison.
The US officers conclusions were if they adopted the 17pdr an HVAP round would give it the killing power of the APDS with the accuracy of the 76mm.

When firing 17 pdr APDS it was recommended that the gunner not try to correct on a missed shot (if the tracer could even be seen), but to aim again at the target. If effect every shot was a first shot.

There really is no simple answer on why the US didnt build the 17-pounder under license. As Mark pointed out "not designed here" didnt stop the US from building other British equipment under license.

A few things to take into consideration. As proposed, and originally tested in summer of 42, the original 76mm gun design (76mm Gun T1) had a much longer barrel then the 76mm gun adopted. The T1 had a length of 57 calibers as opposed to the final 76mm which had a length of 52 calibers. The 17 pounder, by comparison, had a length of of 55 calibers. Problems with balance, among other things, resulted in 15 inches being removed from the length of the T1 and counter weights added. To distinguish the two the original T1 was designated the M1 while the shortened version (which was ultimately adopted) was designated the M1A1.

As might be imagined shortening the barrel that much resulted in a drop off of the velocity of the rounds and decrease in the resulting penetration. The increased velocity of the 17-pounder, along with the ammunition for that gun gave it a decided edge over the M1A1 in penetration. However the higher chamber pressure resulted in shorter barrel life. The British were satisfied to trade shorter barrel life for the increased penetration. The US, being more conservative, were not.

And indeed as Fred points out by the time it became abundantly evident the M1A1 wasnt getting the job done the 90mm was already under development. Meanwhile the "silver bullet" was the HVAP round which did give the M1A1 decent penetration. The trouble is, as Mark once again points out, is production of HVAP never met goals and priority for issuing the round went to Tank Destroyers.

The conversion for M10 TDs to 17pder was easy – much easier than for M4s. A real pitty US ordinance did not go the P51 combo route and marry UK/US tech.

As to ammo how much more plentiful was UK APDS than US HVAP. For wargame purposes I generally allow only 1 shot of each but should APDS be considered a "standard" round?

I regard all of the "Chieftan's" video revisionism with mild disdain.

TomT

As to ammo how much more plentiful was UK APDS than US HVAP.

From what I have read about 5 or 6 rounds of 17pdr APDS per tank once production got going compared to 1 or 2 rounds if at all for 76mm HVAP. All assuming the tanks had a normal supply situation, of course.

The trouble is, as Mark once again points out, is production of HVAP never met goals and priority for issuing the round went to Tank Destroyers.

In all the docs I've seen, I have never come across anything that demonstrated a preference for providing 76mm HVAP to Tank Destroyer units vs. Tank units.

However, the US Army had two different calibers that used the same HVAP projectiles -- 3-inch and 76mm. The projectiles were split rather evenly in making ammunition for the two calibers.

But of course, only the Tank Destroyer command used the 3-inch gun, both in the form of the M6 anti-tank gun and in the M10 tank destroyer.

So half the HVAP went to tank destroyers just because no one else needed 3-inch gun ammo, and the other half was split between tank destroyers and tank units.

Could be that the TDs got the lion's share of the 76mm HVAP. I'm not saying they didn't. Just saying I've never seen any details to support the assertion.

As to how many …

From what I have read about 5 or 6 rounds of 17pdr APDS per tank once production got going compared to 1 or 2 rounds if at all for 76mm HVAP. All assuming the tanks had a normal supply situation, of course.

Until about January 1945, HVAP was little more than a rumor. Really, the rounds were so scarce that most units that received it got 3 or 4 rounds per tank (or TD), but not 3 or 4 rounds every time they rolled out. Just 3 or 4 rounds PERIOD. It was very likely that after the first engagement with enemy armor there would be no more HVAP on the racks for weeks or months.

Several units reported never having seen even one round of HVAP.

By January or February the supply was ramping up, so that in the last months of the war it might be reasonable to assert that a 76mm Sherman might have 3 or 4 rounds on it's racks in a given engagement. Depends on how busy they were as to how long it lasted them.

And BTW the HVAP rounds were considered to be so accurate that they were sometimes used when firing at the gun slits of bunkers, not just at the face of Tigers.

-Mark
(aka: Mk 1)

Sounds like HVAP arrived only when the Germans had run out of tanks.

How would a 76mm Sherman with HVAP have made out against a JS2? Most tests one sees are British or US guns/rounds versus German armour or German guns versus Russian armour, but you don't see many comparisons of British or US guns versus Russian armour.

@4th The Penetration figures for the 76mm HVAP round give 158mm at 500m and 134mm at 1,000m. The JS2 glacis was 100mm sloped at 60 degrees, which if my maths is right gives it around 115mm. So in theory the HVAP round should penetrate 1,000m+, but given the US Army's tests against the Panther when in theory it should penetrate at 500m, but were struggling to get penetrations at 400yds makes me wonder how well it would have coped with the JS2.

It's not that HVAP had less dispersion than the APHE but combined with it's dispersion and flatter trajectory it was more accurate because range error affected it less.
According to:
Weapon Research Committee: accuracy of anti-tank guns and rigidity of gun barrels", 1948 [PRO piece number WO 195/10134],

Gun……….Ammunition…….m.v.(f.p.s.)……Ave m.d. of strike
76mm M1A1…….APC………….2600…………..0.5'
……………..…….AP/T…….……3400…………..0.5'

A couple of quick comments -

> It is my recollection that the unexpectedly poor AP performance of the 76mm APC was ultimately traced to improper/inadequate heat treatment of the projectile body.

> The degree of availability of HVAP in the ETO can be appreciated by comparing its monthly production volume against the number of US tanks and TDs in the field at the time. The monthly HVAP production figures can be found on the web (sorry, can't recall where); add a month or so for the ammunition to make its way from factory to field.

> I've looked into machine gun tactics in some detail and the huge range of techniques employed by MMG/HMG elements is impressive and sometimes quite technically complicated, especially when lengthy ranges are involved. At its crudest and most aggressive, Chinese night attacks of the Korean War would commonly involve hauling MMGs (gun, mount and all) for action deployment within 25-50 yards of a UN defensive position. At a more sophisticated level, entire British MG units (ref the specialist Machine Gun Corps from 1917) would be committed to deliver massed and sustained indirect long-range area denial map fire against sensitive German rear area locations (roads, traffic intersections, towns for example).

> Phil Barker's Armour & Infantry 1925-1950 rules (a good rule set sadly lost in the passage of time) offered some interesting rules on MG area fire and fire along fixed lines that might profitably be revived.

FWIW.

B

Mark;

By early March of 1945 some 18,000 rounds of HVAP were delivered to the ETO. Of those 7,550 were for the 76mm gun while the rest, some 10,550, were for the 3" gun on the M-10. So while production was supposed to be equally split it is clear that production favored the Tank Destroyers. Further 12th Army Group, as one example, decided to split their allocation of HVAP for the 76mm between M4s and the M18 Hellcat. Given that 6th Army Group received relatively few rounds of HVAP it is reasonable to state about 3 to 1 of all HVAP produced overall went to Tank Destroyers vice tanks. So it was a combination of production (approximately 60 percent of HVAP produced was for the 3 inch gun) and distribution (split between M4s armed with the 76 and the M-18 Hellcat) which saw Tank Destroyers favored for HVAP.

The monthly HVAP production figures can be found on the web (sorry, can't recall where); add a month or so for the ammunition to make its way from factory to field.

Butarski – The monthly figures most often quoted are from a two article sequence published on The Chieftain's Hatch at the World of Tanks forums.

I did the research for those two articles. All of the test results and the various statistics (on units, phase lines, availability of tanks, etc.) in the articles came from my studies.

The monthly production figures were provided to me by Rich Anderson of the Dupuy Institute, from his operational research in the US Army Ordnance records at the National Archives.

Following is that information, which I have also posted here on TMP in other threads on one or two prior occasions.

From: link

While they were different guns with different cartridges, the US 76mm and the 3-inch guns fired the same projectiles, at the same velocities. After the Isigny tests, production was immediately ordered on the T4 for both the 76mm gun of the Sherman and M18 tank destroyer, and the 3" gun that served as a towed gun and in the M10 tank destroyer. The initial production order was for 20,000 rounds. Then a target of 43,000 rounds per month was set for the remainder of the year, and 10,000 rounds per month thereafter.

Production was slow to ramp up. The tungsten carbide steel used as the core of HVAP rounds was a critical war material, and was in demand for many wartime production requirements. Shooting it out of barrels at the Germans was a new requirement that only added to the stress on supplies. The 43,000 per month target for 1944 was quickly abandoned. Even the more modest rate of 10,000 per month was not reached until November of 1944.

The first 1,000 rounds of 76mm T4 produced in July were sent by air to ETO in time for the Isigny tests. The portion that remained after testing was issued to the troops. A second shipment of 1,000 3" T4 rounds was also shipped by air, in August. But after that, the rest came by normal surface shipping. After August, the receipt (NOTE: My research indicates that these numbers are PRODUCTION, not RECEIPT IN ETO -Mk 1) of HVAP rounds for the 3-inch and 76mm guns through the end of the campaign in ETO was:

Month / Year ……. 3-inch HVAP ……. 76mm HVAP

Sep 1941 ………….. 1,000 ………… 1,000

Oct 1944 ………….. 2,000 ………… 1,000

Nov 1944 ………….. 5,000 ………… 5,000

Dec 1944 ………….. 5,000 ………… 5,000

Jan 1945 ………….. 7,000 ………… 6,000

Feb 1945 ………….. 6,000 ………… 6,000

Mar 1945 ………….. 3,000 ………… 9,000

Apr 1945 ………….. 3,000 ………… 5,000

May 1945 ………….. 0 ……………. 6,000

Normal shipping time for munitions from the US to ETO ran about 10 weeks. It was not until mid-January that HVAP rounds received in ETO exceeded 2,000 per week. … It was only in 1945 that tank units received enough HVAP ammunition to carry the oft-quoted 2 or 3 rounds per tank.

By early March of 1945 some 18,000 rounds of HVAP were delivered to the ETO. Of those 7,550 were for the 76mm gun while the rest, some 10,550, were for the 3" gun on the M-10.

Marc: Interesting numbers. Based on production, I would have expected closer to 38,000 rounds of HVAP to have been shipped to ETO by March, with a very slight edge to 76mm over 3-inch.

Is it possible that your numbers track only the T4 HVAP projectile? Production switched to subsequent HVAP projectile types in late fall and winter (IIRC 3 sub-variants of T designation racked up some meaningful production numbers before it was standardized as an M version in the late winter/spring of 1945).

In any case I would be interested in the information on receipt of HVAP in ETO, as I have only ever found info on production.

-Mark
(aka: Mk 1)

How would a 76mm Sherman with HVAP have made out against a JS2?

It greatly depends on which version of the IS-2 we are discussing.

If the IS-2m1944 (also frequently called IS-2m, or just IS-2), versus the original IS-2m1943 (frequently incorrectly called the IS-1), then the 76mm Sherman, HVAP or not, would have been greatly under-gunned.

@4th The Penetration figures for the 76mm HVAP round give 158mm at 500m and 134mm at 1,000m. The JS2 glacis was 100mm sloped at 60 degrees, which if my maths is right gives it around 115mm.

If we are speaking of the original IS-2 (the m1943), your slope is about right for the stepped glacis, but I think your thickness is off. If we are speaking of the IS-2m (or m1944) I think you might have inverted the slope figure.

The most common equivalent I've seen rates the IS-2m glacis at ~160mm LOS. Meaning penetration was unlikely even at close range (unless striking some imperfection or seam). The turret would have been the more profitable target, but it had a lot of rounding and slope.

The US Army and other Western allies were quite concerned about IS-2s. The concern that the Chinese might use IS-2s in what was then French Indochina (North Vietnam) was the primary reason that the French sent M36 tank destroyers to Hanoi instead of Shermans, despite having Shermans in greater numbers and seeing it as superior for fighting against the light-infantry force of the Viet Minh.

-Mark
(aka: Mk 1)

Mark;

While I have seen the numbers in various places this source is a good summary.
link

I am wondering now if part of the problem may have been more HVAP was available stateside but no priority given to its delivery.

By the way, good discussion!

If we are speaking of the original IS-2 (the m1943), your slope is about right for the stepped glacis, but I think your thickness is off. If we are speaking of the IS-2m (or m1944) I think you might have inverted the slope figure.

Yes the stepped glacis is 60mm not 100mm at 60 degrees so around 120mm equivalent.

The most common equivalent I've seen rates the IS-2m glacis at ~160mm LOS. Meaning penetration was unlikely even at close range (unless striking some imperfection or seam). The turret would have been the more profitable target, but it had a lot of rounding and slope.

That seems a bit low as a 60 degree slope doubles the armour thickness, but it mean the IS2 is out of the league of the 76mm gun even with HVAP.

Marc:

Good find. I have that book somewhere at home (somewhere…). I should try to find it to see what other gems are in there that I don't recall.

Shame I didn't observe this some time back. Might have asked Zaloga about it (although I doubt he would have had any information at top-of-mind unless it was a topic of current research when I brought it up). In my conversations with him (admittedly several years ago now) the topic of number of rounds of HVAP in theater never came up, although we did have some interesting exchanges on the Panther in general.

That said, I think the general info in that book fits my impressions as well. Production of T4 projectiles pretty evenly divided between 3-inch and 76mm rounds. 76mm HVAP pretty evenly distributed between TD and tank units. Three sub-versions of HVAP before before standardization from T4 to M93, improving the AP performance against highly sloped armor. I don't recall ever seeing the reference to "an unground tungsten core" before.

But by the time the M93 HVAP was approved, it was a pretty solid performer. This round became commonly available in the post-war Army, and was the primary (not "silver bullet", but primary) AP round that US M4A3E8s used for killing T-34-85s in Korea.

-Mark
(aka: Mk 1)

Mark;

I too have heard Mr Zaloga speak on several occasions and have always come away impressed. My only wish is that he would footnote his material more. I have no doubt he is correct but what other information would his resources provide us.

Talk about good timing:
New pdf THE 76-MM GUN M1A1 AND M1A2: AN ANALYSIS OF U.S. ANTI-TANK CAPABILITIES DURING WORLD WAR II
PDF link

Boggles the mind that a brand new report on a topic over 70 years old. Incredible amount of information and the Conclusion section alone is gold. WELL done Mobius.

Aware the 7.6L/7.5L HVAP was rare but what about APDS for the 5.7L? How rare was the Brit round?

TomT

Interesting link Mobius. It is the first US document I have read which admits they could have done better.
"The decision to cut barrel length of the M1 instead of rebalancing the M18 turret reduced the capability that would have ensured successful performance against heavier German armor."
"The early war 76-mm development efforts was a missed opportunity to significantly improve upon the 3-in. gun. The lesson learned from this is to ensure that your capability exceeds the projected threat because just good enough now may not be in a few years' time."
This is another interesting quote "Doctrine stated that the role of a tank was for infantry support, not fighting other tanks. Armored Forces Field Manual: Tactics and Techniques (FM 17-10) listed tank versus tank combat as "special operations" with less than a page devoted to the subject (ref. 6)."
Maybe the flawed tank destroyer doctrine is not a myth.

TD doctrine isn't exactly flawed, but there was a horrible under-appreciation for how much mobility it would take.

No ground vehicle is fast enough to respond to armored breakthroughs (especially not when you're talking Abrams or T80s!), so your basic tank needs to spend a significant amount of time fighting other tanks, not just supporting infantry.

But attack helicopters follow the WW2 Tank Destroyer doctrine pretty closely.

+1 to Picatinny Arsenal for shedding some long overdue light (however polite the language) upon the embarrassing bureaucratic bungling of US tank armament development during WW2.

BTW – For those so interested, TM9-1907 Ballistic Data Performance of Ammunition dated July 1948 contains armor penetration graphs for the 76mm M93 HVAP-T and the 90mm M68 APC-T, M82 APC-T and 90mm M304 HVAP-T as well.

B

The Panther problem was discovered in June 1944 and a solution was in place by the end of the year. The Germans found a similar problem in June 1941 and took far longer to introduce their antidote to the T34.

The Panther problem was discovered in June 1944 and a solution was in place by the end of the year. The Germans found a similar problem in June 1941 and took far longer to introduce their antidote to the T34.

Except it wasn't as HVAP remained very rare until the end of the war. The allies had faced the Tiger in early ‘43 and I assume would have learned of the Panther before June 1944. I make that 2 years before they found a solution. They counted on being able to continue business as usual which was very shortsighted went into production in November ‘41, so that is 4 months after the start of Barbarossa and the Germans had their own HVAP for the 5cm L42 which would penetrate a T34 upto 500m.

The Western Allies did not get a Panther to test until spring 1944. The Tiger was encountered in Tunisia and was found vulnerable to the 6 dpr and the 17 pdr was also introduced in Tunisia. What we see is the normal cycle of each side leap-frogging each other.I fail to see why the Panther gap in summer 1944 should be considered any different from say the FW 190 scare in 1941.

See the cited Picatinny Arsenal essay –

"The U.S. Army got a first look at the Panther tank in 1943 after the Russians captured some on the Eastern front. Liaison officers were offered an opportunity to examine the new tank and report back. The improvements were noted, but the Panther was not considered a tremendous threat since there were not great numbers produced in at the time (ref. 7). The new information did not alter development programs to compensate for the improvements. The M1 76-mm Gun and its ammunition were not upgraded as a result."

The USA was informed in detail regarding the Panther tank by late 1943. Physical testing of a captured example would certainly have been desirable, but ignoring the implications of the 80mm frontal plate laid back at 55deg that was staring those US observers in the face is hard to square with prudent forward planning. US Armored Forces was specifically aware of the Tiger I through personal experience and likewise chose to ignore the threat. Conversely, staring in 1942 the British Army was undertaking a crash program up up-gun its tanks, first the 6-pounder, then a 17-pounder armament. This was also ignored by the USA stateside bureaucracy.

The Soviet Union was rapidly up-gunning its tanks as well, first lengthening it 76mm tank gun, then immediately undertaking an up-gunning program to 85mm after the inadequacy of the 76mm versus the new German heavy tanks became apparent. They did not stop the upgunning effort until caliber reached 122mm in the JS series. Once again, the US stateside bureaucracy ignored development.

As for the Germans? They had commenced a tank up-gunning program even before Barbarossa. Say what you like about Germany, but the lessons of those heavily armored Chars and Matildas were not lost upon them. As soon as the T34 (and KVs were encountered in the East, the long barreled 50mm upgrade program was immediately abandoned and replaced by a move to a long-barreled 75mm. Germany had long-barreled 75mm tanks in field service within a year. Nor did Germany stop there; they moved directly very high velocity 75mm, 88mm and high velocity 88mm for all their new tank projects, as well as 128mm for their largest TDs.

B

Well the fact is no examination of the Panther was conducted until one of the Kursk examples was sent to England in early 1944. There was no time to do a thorough test before June 6 and it was too valuable to be tested to destruction. Despite claims to the contrary there was no real 'advance warning' of the Panther problem.

Note the date of the first ever examination of a Panther in England-May 1944

I got this report from the net but don't have the link. I am sure a Google will find it. Note the report mentions the possibility of a deflection of a shot down into the crew compartment off the bottom of the mantlet. The report was distributed just before D-Day and I believe it to be the source of the claims Panthers were disabled by such 'lucky shots'.
This is the tank:

This may be the link which I think was posted here before.
link

The above link is a test of 3 Panthers captured in Normandy and is late 1944.They were tested to destruction.

You are rather missing the point, mkenny.

B

Yep that's me, Woefully misinformed-except I know when the first Panther was tested and thus claims of a '1 year advance warning' of the problem are bunk.

@mkenny The point is the US did not need advanced warning of the Panther problem, they should have anticipated it. Taken what they knew of existing German armour, ie Tiger, and planned to leap ahead of that in gun power. The US officers who compiled the report that Mobius linked to admit this was a failing. Instead of redesigning the 76mm gun to fit the M18 they should have redesigned the M18 so the gun would fit. It is like running this seasons Gran Prix circuit with last years car and assuming because it won the championship last year it will do so again. There was a gun/armour race going from the start of WW2 except the US didn't join in. By contrast the design of the 17pdr started BEFORE the 6pdr entered production. The Brits had already realised the 6pdr would be outclassed.

The point is the US did not need advanced warning of the Panther problem, they should have anticipated it.

Fred:
Do you have perfect predictive ability on topics on which you have little first-hand experience? If so, please advise me on where the price of Tesla stock will be in June of 2019, as I would like to make some important decisions.

Taken what they knew of existing German armour, ie Tiger, and planned to leap ahead of that in gun power.

Taken what they knew of existing German armor, ie Tiger, the US Army decided that Panther was nothing to be too concerned about.

The evaluation of Panthers post-Kursk, observed that the weight of the tank was a bit less than the Tiger (true), and that the armor was less than Tiger (true), and that they were organized into independent formations (true at Kursk), and judged that the Panther was an attempt to make a "Tiger-light".

The Tiger was not, never was, and never could be a threat to the US Army operational initiatives. There was no case were Tigers ever prevented the US Army from doing anything it planned to do. They were too few in numbers, too rare in combat, and too limited in mobility to be an influence on operations. There is no case of Tigers producing positive operational results anywhere. When they were deployed in campaigns against the western allies, the units using them regularly lost 100% of their vehicles. No Tigers sent to Tunisia returned. None of the 134 Tigers (and Tiger IIs) sent to Normandy made it back across the Seine.

Tigers were engaged in Tunisia. They had no effect on the campaign. They were handled by 6pdrs, by field artillery, and mostly by sand and dirt and interdicting the supply trucks. Ordnance testing showed (incorrectly) that the 3-inch gun of the M10 could penetrate the Tiger frontally at reasonable combat ranges. The 76mm gun was ballistically matched to the 3-inch gun, and so something that was less than a Tiger would be even less threat than the Tiger, and the Tiger was already shown to be no threat to US Army operations.

I am not saying this is my view. I am saying this was how the US Army saw things, based on experience from Tunisia.

The mistake in the US assessment of the Panther was the conclusion that it was a replacement for the Tiger, when in fact it was a replacement for the Pz IV. They saw it as a Tiger that was easier to kill. In fact it was intended to be a Pz IV that was harder to kill. This was the critical perspective that the US Army evaluation in 1943 missed.

And BTW, even given how little actual ongoing experience the US Army had in armored combat, and even given that the US time from factory to front was 6 to 8 times longer than most other combatants … even given those limitations, as mkenny points out the US time to remedy shortcomings was in fact shorter, rather than longer, than British, German or Russian responses to similar weapons deficiencies.

There was a gun/armour race going from the start of WW2 except the US didn't join in. By contrast the design of the 17pdr started BEFORE the 6pdr entered production. The Brits had already realised the 6pdr would be outclassed.

US Army Ordnance had mounted 76mm guns in Shermans by the end of 1942. The US Army Tank Board rejected the design due to concerns over cramped turret space (it was notably better than the later British Sherman Firefly, and was revisited and used in the post-war period as means of up-gunning earlier marks of Shermans for post-war aid programs -- see the Shermans used in Kelly's Heros, for examples of this conversion).

US Army Ordnance put a whole new turret with the 76mm gun on the Sherman in late 1943 (before the T-34-85), and production was approved and begun in early 1944 (before the T-34-85). 100 were available in the UK prior to D-Day. No units would accept them, as the unit commanders saw no need.

The 2nd Issigny tests were conducted on 20 August 1944. The first drafting of the post-test report was 22 August. It was finalized and distributed several days later. It identified a clear shortcoming in US guns and ammunition facing the Panther. In LESS THAN A MONTH the first M36 tank destroyers, with the 90mm gun, were issued to units in ETO. This gun was superior to the 17pdr in accuracy, in armor penetration, and in destructive power. It also threw a very useful HE round.

To suggest that these timeframes do not show any anticipation of future trends in the guns-vs-armor race seems to be a rather selective reading of history to me.

The problem was not that no one anticipated the guns-vs-armor race. The problem was consensus. Without extensive battlefield experience, there was no consistent voice to drive development, production, and issuing of new weapons. Even in that environment, development and production (for the most part, but perhaps not for HVAP) stayed ahead of the game for the most part. It was deployment that fell behind.

If you were running the show, would you have just ignored inputs from the front line units? Just let the propeller-heads back at development in the states dictate what the troops needed without asking the troops? It was the FRONT LINE UNITS that could not provide any consensus on need. And they could not provide consensus because they didn't have enough experience.

I mentioned above how the first 76mm armed Shermans were already available in the UK before D-Day, but were rejected by the frontline units due to no perception of need. As another example, as late as the fall of 1944 the US 6th Armored Division in ETO reported it had NO 76mm-armed Shermans, and saw no need for 76mm-armed Shermans. Bother with HVAP, they didn't even want the guns to fire it from! The most consistent feedback from US armored formations through the summer and fall of 1944, both in the Armored Divisions and in the independent tank battalions, was praise for and desire for more Sherman assault guns with the 105mm howitzer.

That same 6th Armored Division reported two months later that it wanted primarily 76mm armed Shermans going forward. It reported two months later that it's crews had lost confidence in their equipment because they were undergunned. These were the SAME guys who didn't even WANT up-gunned Shermans just 4 months before.

For the US, half a world away from the theater of combat, it typically took MORE than 4 months just to SHIP something to the front, bother with a development, acceptance and production cycle.

And yet even though the US Army was equipped with a tank that so many post-war voices assert was clearly useless in combat, the German army was crushed, their armored units out-maneuvered and destroyed across the board, every planned phase-line timetable for ETO was exceeded, and the war was ended before the US reply to the "Panther panic" could be deployed across the US Army forces in ETO.

D@mn those troopers for winning the war before future wargamers' laments could be resolved.

-Mark
(aka: Mk 1)

Fred:
Do you have perfect predictive ability on topics on which you have little first-hand experience? If so, please advise me on where the price of Tesla stock will be in June of 2019, as I would like to make some important decisions.

Very glib Mark! As you seem to know it all I am sure I don't need to give you any tips!

The mistake in the US assessment of the Panther was the conclusion that it was a replacement for the Tiger, when in fact it was a replacement for the Pz IV. They saw it as a Tiger that was easier to kill. In fact it was intended to be a Pz IV that was harder to kill. This was the critical perspective that the US Army evaluation in 1943 missed.

Which was what I was saying. The US made a mistake in assuming what was current in 1943 would stay that way through 1944. That was in the link that Mobius provided and is from the US Army's own evaluation. The point is quite specific.
"The decision to cut barrel length of the M1 instead of rebalancing the M18 turret reduced the capability that would have ensured successful performance against heavier German armor."
"The early war 76-mm development efforts was a missed opportunity to significantly improve upon the 3-in. gun. The lesson learned from this is to ensure that your capability exceeds the projected threat because just good enough now may not be in a few years' time."

To suggest that these timeframes do not show any anticipation of future trends in the guns-vs-armor race seems to be a rather selective reading of history to me.

Well that was the US Army's own evaluation of its performance certainly in respect of the 76mm gun. The British using the same calibre produced a better gun with good penetration from standard AP shot.

If you were running the show, would you have just ignored inputs from the front line units? Just let the propeller-heads back at development in the states dictate what the troops needed without asking the troops? It was the FRONT LINE UNITS that could not provide any consensus on need. And they could not provide consensus because they didn't have enough experience.

I think that is the way other armies did it Mark. Particularly the Russians. Had the T34 been submitted to the US Tank Board it would have been rejected I am sure. And yet the Soviets built thousands of them and used them to comprehensively beat the Germans. And yes I know they had lend lease and some of those wonderful Sherman's, but the bulk of the fighting was done by home produced armour. The same would apply to all the early British armour the faults of which have been well documented. All armies collected data on the performance of their tanks and feedback from their troops who used them, but unlike the US Army the end users didn't call the shots. A British or Russian commander saying they didn't want the Firefly or T34/85 would have cut no ice with the high command.

US Army Ordnance had mounted 76mm guns in Shermans by the end of 1942. The US Army Tank Board rejected the design due to concerns over cramped turret space (it was notably better than the later British Sherman Firefly,

Despite your disparaging of the Firefly the British seemed pretty happy with it and fought with it very successfully. In fact so happy with it that they increased the allocation. Maybe the US Army tank board were too fussy!

And yet even though the US Army was equipped with a tank that so many post-war voices assert was clearly useless in combat, the German army was crushed, their armored units out-maneuvered and destroyed across the board, every planned phase-line timetable for ETO was exceeded, and the war was ended before the US reply to the "Panther panic" could be deployed across the US Army forces in ETO.

I am pretty sure there was a lot more to it than just the Sherman Mark! Generalship, logistics, air support, training, morale, naval power and a touch of genius. Take the Mulberry harbours. Can't capture a port to land supplies, never mind we will bring our own. And don't forget the British and Commonwealth forces played their part with their Sherman's, Churchill's, Cromwells, Comets and the useless Firefly. The success of the British and Commonwealth in grinding down German armour in Normandy is shown by the Mortain counterattack when the 5 Panzer Divisions engaged could barely muster more than a single divisions worth of armour.

US Army Ordnance put a whole new turret with the 76mm gun on the Sherman in late 1943 (before the T-34-85), and production was approved and begun in early 1944 (before the T-34-85). 100 were available in the UK prior to D-Day.

True for the T34/85, but you neglected to mention that the SU85 went into service in August ‘43, The IS1 in October ‘43 and IS2 in February of ‘44 and the first SU100 was ready in March ‘44 and went into full scale production shortly after. The Soviets had plenty of armoured vehicles with capable guns by the spring of 1944.

No units would accept them, as the unit commanders saw no need.

Somehow I can't see that happening in the Red Army. "So you don't want the new tanks, Comrade. Here is the telephone. Why don't you phone Comrade Stalin and tell him you don't want the wonderful new tanks he is sending you!"

The US 90mm was superior to the 17-pounder in AP performance? Really?

The US 90mm was superior to the 17-pounder in AP performance? Really?

90mm APC slightly inferior to 17pdr APC, 90mm HVAP slightly superior to 17pdr APDS.

This may be pertinent, but I've only had a quick glance through after it occurred to me to see what might be on fold3.com, others may be able to put it into context.

From 'First United States Army, Report of Operations, 20 October 1943 to 1 August 1944'. Annex No.13, Ordnance Section (Inclosure 1 to Appendix 1); Expenditures 6 June to 31 July inclusive (pgs 73-75).

57mm AP – 55,184
57mm APC – 26,572
57mm SABOT – 6302

Don't know if that's of import to the original post. I can't think of anything else in US service than the regimental antitank gun that was 57-mm calibre.

Gary

The 17 pdr was slightly superior to the 90mm M82 shell but the 90mm T33 was slightly superior to the 17 pdr.