Monday 16 October 2017

Penetration: British Edition

On March 31st, 1944, a demonstration of various British vehicles was held at the Lulworth proving grounds in Great Britain. The usual fare of British and American tanks were accompanied by something a little more exotic.

Comparative firing demonstrations means that we might get another penetration table done to one standard, like this one! Unfortunately, we are not so lucky, and the KV-1 only has the muzzle velocity recorded.

There are some interesting comparisons that can be made here nonetheless. Let's compare the numbers for tank guns present in both tables. The Tiger's gun penetrates 102 mm of armour at 1000 meters at a 30 degree angle, and 84 mm in the same conditions by Soviet standards (interestingly enough, the penetration at normal is almost the same). The KwK 40 from the PzIV penetrates 83 mm vs 60 mm by Soviet standards. Here, the penetration at normal is still significantly less than the British value. The German data disagrees with the British as well: according to them, the PzIV and Tiger's guns penetrate slightly less in these conditions, 82 mm and 99 mm respectively.

The British guns also perform significantly differently. By Soviet standards, the 6-pdr only penetrates 39 mm, while the British credit it with 53 mm of penetration. Same as the KwK 36, the gun does not performs close to British expectations when the plate is placed at normal. Interestingly enough, the gun had a higher muzzle velocity when tested in the USSR (837 m/s vs. 830 m/s). According to Soviet trials, the 17-pounder could penetrate 100 mm at 1000 meters and 30 degrees, versus the British 120 mm figure, which dispels the notion that Soviet-derived penetration values are lower than those in foreign tables because they are calculated.

The American 75 mm gun has a lower muzzle velocity (590 m/s vs 618 m/s on the British table), but once again falls far short of  the Soviet standard: 63 mm in the UK, 39 mm in the USSR. 


  1. values seem to change by date quite a bit during the war depending on the testing done at the time and the plate tested against.

    At times they have some guns as estimations as firing tests have not yet been fully finished on them, and later dates are actual results.

    March 1942 80% estimation for a few guns

    1943 results



  2. "Comparative firing demonstrations means that we might get another penetration table done to one standard, like this one!"

    The penetration figures from this table are based on DeMarre formula, factor K=2400. The front page of the CAMD RF 81-12038-303 report acknowledge that:

    "Расчетная при к=2400" - Estimated with K=2400

    Link to the missing front page:

    " [..] which dispels the notion that Soviet-derived penetration values are lower than those in foreign tables because they are calculated.

    But that's what they are, I don't know why you refuse to accept it. The German themselves made a lot of guesswork for their anit-tank pamphlets. The glacis of the Panther was descirbed as invulnerable to the Soviet 122mm gun. Yet we know that any hit to the glacis would be completely destructive, and leave nothing but gaping holes.

    1. Correct. Soviet figures with De Marre K=2400 quoted here again are calculated based upon the presumption of exactly similar projectile-armor energy interaction as encountered by soviet domestic AP projectiles striking their armor. It has nothing to do with TESTS. Soviet AP was characterised by uncapped designs, a low surface hardness, a low degree of impact (Charpy) toughness and low alloy composition with some examples of poor hardening treatments, which caused their projectiles to be inferior to other in armor penetration.

      In terms of penetration standart, the russion CP=80% and IP=20% were both inferior to the german G(D)=100% penetration standart.

    2. Penetration values from practical trials held by the Soviets routinely result in less penetration, even with foreign guns and foreign shells. I give many examples of this. Hell, there's even one in this article. I know that it's easier to keep hammering at the "Russian stuff sucks" angle, but come on, put some effort into reading first.

    3. I'm not on a bandwagon to rrrrreeeee "russian stuff sucks". The linked penetration table (CAMD RF 81-12038-303), does not orginate from a "comparative firing demonstrations" as stated. The linked article itself, notes that the Soviets used "whatever ammunition that was captured alongside German tanks", to perform these "tests". However, that just frenzied speculation, and even collide with the report's covering page, that states: "Расчетная при к=2400"

      I can't see any other Soviet penetration data of "foreign gun tests" that you have linked, except the calculated data from the CAMD RF 81-12038-303 report.

    4. "According to Soviet trials, the 17-pounder could penetrate 100 mm at 1000 meters and 30 degrees, versus the British 120 mm figure"

      That's just one example. Shooting against PzIIIs, the British record their 2-pounder as capable of penetrating the 50 mm of homogeneous front armour from 200 meters, Soviet trials say it can't penetrate at all. The American 37 mm penetrates from 500 meters in British tests, 100 meters in Soviet tests.

    5. "Penetration values from practical trials held by the Soviets routinely result in less penetration, even with foreign guns and foreign shells."

      Quite the opposite. KWK43 exceeded penetration at 60° impact on soviet cast armor and 55° on 110mm soviet RHA by some 15%-20% compared to german official penetration G(D)vs german RHA.

      And mind that the 17pdr penetration was not tested to it´s maximum according to the article, only 100mm and 90mm plates were used. No 120mm plate was used in the trial.

      Again, I don´t expect You to understand this.

    6. Yes, and the PzIII trials were performed in a holodeck, I'm sure. Also everything is so rigid in the USSR that plates can't be placed at an angle to figure out penetration at normal, right?

    7. You wer ethe one, who stated incorrectly that:
      "Penetration values from practical trials held by the Soviets routinely result in less penetration, even with foreign guns and foreign shells."

      I just pointed out You are wrong again. These are the facts, if You don´t like them, that´s Your problem, not mine. Facts are facts. For everything else, get a psychologist.

    8. Yeah, facts like the British saying that certain guns can penetrate the PzIII in certain conditions and the Soviets saying that the same guns under the same conditions can't? You mean those facts?

    9. This comment has been removed by the author.

    10. "You wer ethe one, who stated incorrectly that:" If your hand shakes, take a break.

  3. This comment has been removed by the author.

  4. Just to be clear, British standards did change throughout the war. As previously mentioned, UK Standards prior to 1943 were quite similar to Russian in a lot of ways, they demanded penetration of plate 80% of the time and they considered a success to be more than 80% of the projectile passing through the plate.

    Later, in 1943 they relaxed their standards, likely to standardize and match more closely American standards, a 50/50 standard of penetration and considered any more than 20% of shell mass (or, in the case of a subcalibre, "most" of the core had to penetrate. This is usually defined as 80%+ of the core)

    Almost all British guns were proofed by firing versus various plates rather than estimations, although the initial performance was estimated and then verified by firing trial. The British also did not consider firing versus "foreign" or "captured" tanks to be much use in trialing of guns, mostly due to the apparent inconsistency of foreign armoring. They did trial guns versus specific tanks to verify performance, in the case of German tanks you'd find a variety of differing performance from individual vehicles due to inconsistency in german production quality, something I'm sure the Soviets were well aware of.

    When it comes to odd discrepancies such as the 2 Pounder and 6 Pounder performance versus the Pz III and Pz IV I am often left pondering myself. UK trials are quite detailed and quite clearly show those guns having the performance listed by the British rather than the Soviet claims. There are several explanations for this that I can think of, ranging anywhere from. "The UK shipped mostly poor performing ammo to the Russians- pawning off bad batches of ammo (which did exist)." to "Soviets simply fudging the numbers to make their own equipment appear better." (which seems unlikely, but has been noted by a number of other (admittedly, most western) authors

  5. The british differentiated between penetration (crack / hole through plate whether or not the projectile went through) and perforation (physical passage of the projectile through plate, regardless of it´s condition).

    It must be noted that the british generally did not use HE filler in their domestic tank and anti tank based AP-ammunition (unlike soviets, germans, US, and others). That was done for two reasons:

    (I) to improve the penetration (every cavity degrades robustness of the body)
    (II) problems in developing a suitable delay fuze and filler combination at the intended striking velocities, which detonates both, reliably and high order behind differently thick plate.

    These two concerns were universal and posed challanges for other services, too.

    However, because there was no explosive filler present, the british AP ammunition -capped or not- was never specified to NEED to remain intact during penetration (this was a very serious prerequisite for any high order detonation after perforation, and a constant issue for soviet AP -the reason why the germans had to produce their own sort of AP ammunition for captured soviet 76.2mm guns, despite having also captured large stocks of BP-350 and BP-350A ammunition).

    Soviet high hardness armor plate is suited to degrade penetration of projectiles by breaking up the AP. In this regard, it is more capable to damage incoming projectiles than either US, british or german RHA. That was because soviet armor was tuned to soviet AP and therefore was optimized to break up more completely the relaitively easy to damage domestic, uncapped AP. The strength of this armor partly relies on attributes of the attacking projectile. In turn, it made it better against weaker- but also considerably poorer against stronger projectiles than other forms of armor, due to a higher susceptibility for adiabatic shear failure against intact projectiles of these plates.

    1. I do agree that the concerns, particularly with fuze delay, filler and the serviceability of fuzing was fairly universal. This is seen by UK and USA comparative trials in late 1943 where less than 1/3rd of 76mm AP (M62) shots in one particular trial functioned correctly due to either premature or utterly nonfunctional fuzing post-penetration. This was at the cost of reduced penetrative performance and increased cost. This was the same reason that when comparing the 90mm and 17 Pounder, (M82 APCBC and 17 Pounder APCBC Shot) the 17 Pounder, even though it fired a lighter shot was actually a significantly more capable ammo- with the high failure rates, variants of performance and high prevalence of shatter, even in American capped ammo.

      And to be clear, yes the British differentiated between perforations and penetrations, they noted them in trial reports they were very careful to make note that one and another different. They also noted penetrations were the shot totally broke up, as well as when "failure to penetrate" resulted in significant plate breakup, or spalling even though it neither penetrated or perforated.

      I think it also should be noted that after the war, almost everybody immediately ditched their fuzes and bursting charges and switched to either solid shot (in the case of American 90mm and 76mm ammo, or British 84mm ammo) or Tungsten subcalibre of various types.

    2. The only/main reason to produce own AP amunition for 76,2 mm guns was soviet projectile penetration behavior ? Not realiable ammo suply ? Plus german ammo while heavier, has higher muzzle velocity 740 m/s vs 690 m/s.

  6. OhSlowpoke,

    unfortunately, my previous response was "filtered out", though, I´d like to add to Your comment that the move towards unfilled AP postwar was partially in response to the advent of highly inclined, and thick armor plate on vehicles during and after ww2. These presented an even more formidable challange in the design for any working delay action projectile due to the problems associated with base slam at highly oblique impact.
    Germany started the war with workable solution in the 0° to 30° obliquity range and developed solutions late in 1944 which allowed them to increase the severity of the service proof specification to 45°. Still, low order detonations and inconsistent delay time were not infrequent occurances on the prooving ground.
    At 60° obliquity, and against ca. calibre sized, good quality homogenious armor plate, even those projectiles often broke up with only rarely a run of projectiles passing effective (at much elevated velocity compared to the velocity required for holing).
    Successful fuze action would require a major review of the basic AP concept (they had good results with experimental caps sleeved down to the base)or a shift to HEAT, which presented an easier solution to the problem.

  7. "The KwK 40 from the PzIV penetrates 83 mm vs 60 mm by Soviet standards."
    Still with those calculated numbers it can penetrate the front hull of a T-34 at 1000m.
    So says this article:

  8. "The KwK 40 from the PzIV penetrates 83 mm vs 60 mm by Soviet standards."

    KWK40 data in CAMD RF 81-12038-303 is calculated based upon the inferior soviet AP quality standart (K=2400) and does not represent actually testet data.

    Pz4 lang defeated frontally IS2 with two hits, both clean penetrations (one at mantlet where thickest, one on driver hatch) from battle range using Pzgr39. That would be difficult with just 70mm @30° penetration, even considering the low ballistic resistence of the cast armor present in the IS2.

    1. Your claims get more and more vague. No source as always. What is "battle range"? Why are you sure that it's 1000 meters?

    2. "After receiving three shots from the 88 mm Tiger's rounds on the nose from a distance of 1000-1500 metres, tank No.4032 was destroyed by fire from another Tiger some 400-500 metres away. An 88 mm armor-piercing round penetrated the sloped armor plate from the right side. First the shell-case charges ignited, and then the fuel. The crew left the tank and evacuated the driver to the rear."

      "Tank No.40254 was damaged from a distance of 800-1000 metres, by a "Ferdinand" in ambush. The first round did not penetrate the turret ring, but the second round put the engine out of order. The crew was evacuated and the tank was burnt out on the battle field."

      This are first models in combat, where problem with armour density can relate to.

      "Tank No.40255 received a direct hit by a 88 mm round of "Tiger" in the frontal lower plate at a the distance of 1000-1100 metres. Because of that, the left fuel tank was penetrated and the driver was wounded by a fragment of armour. The rest of the crew received light burns. The tank was burnt out."

      Another tank hit to the lower frontal plate. Fuel tank ignited, driver get wounded by fragment of armour and rest received light burns (when helping to the driver ?). Projectile could do more demage if it get to the tank. This seems to me that it did not get to the inside.

      Your memo is probably deep extract. PzGr. 39 can not penetrate mantled on its thickest point and highly probably ca not penetrate IS-2 by two shots from two two shots from normal battle distances to the front. Even side and back armour can be problem at 1000 m, if the tank is angled to the gun by 20 degrees less or more than 90. Later model could be penetrated to the mantled above and under gun optic aperture where is around 80 mm and behind no armour. In one ocasion PaK 40 scored such lucky hit. Also M-26 was pentrated by 88 mm in similar instance.

    3. Pz4 lang defeated frontally IS2 with two hits, both clean penetrations (one at mantlet where thickest, one on driver hatch) from battle range using Pzgr39.

      Anyone can get a lucky shot or two (like, where did the shots hit, precisely? Did the hit on the turret just happen to hit the hole in the armor for the gunsight?? (that happened to the IS-2 turret front on display at the New England military museum)). To quote John Salt, in war one can always find instances where a shot that should have had a near-100 % chance of penetrating didn't, and instances where a shot that had near-zero chances did.

      In practical terms, though the Pak 40 was (Zaloga's description) "almost useless" against the front of the IS-2 (maybe lower plate, near point-blank range, being their best chance). Don't go by outlier data. I also note a King Tiger crew reported bouncing not two but *seven shots* off an IS-2's front at 1500 m, where the data you cite has the 88/L71 as superior to the 75/L40 firing at point-blank range. I'd say for statistics, a sampling size of 7 beats a sampling of 2 any day. Tiger I crews for their part reported that an IS-2 (model 1943, not the significantly improved model 1944) required closing to < 500 meters to achieve penetration, an assessment which agrees with the Germans' own WaPruf evaluations.

  9. IS2 armor would be resistent if it would be on par with german RHA. Official german battle instructions state that due to the use of cast armor for important frontal armor areas, the resitence is so low that IS can be penetrated by 75mm KWK40 from battle range.

    Vortragsnotiz "Feststellung über einen neuen schweren Panzer, vermutlich "Joseph Stalin", dated 16th of May, 1944.

    Kill was achieved by Pak 43/1 (Hornisse)from 2600m by clean penetration through the most reinforced part of the mantlet. Two shots on the shallow forward slope ricochetted off.

    A “Joseph Stalin” tank which was engaged and destroyed by AOK 8 at the beginning of May was hit by a Panzer IVL from 500m, once in the turret and another shot went into the frontal hull hatch. Both resulted in a clean penetration, the tank burned out.

    1. Ah ok, so instead of a proper test it's an unconfirmed kill claim, which we know are always reliable. Good to see that your standards of evidence are as high as ever.

    2. 1) This is an IS-2 model 1943 with the small gun mantlet and less turret protection. But funny, you claimed this very hit from the 88/L71 cited was the same as the one shown on the captured IS-2 in Peter's article here:

      Where the hole in the armor is clearly NOT on the gun mantlet, but on the weakest point of the IS-2 front turret armor (right near the edge of the mantlet). So what's what?
      How many IS-2s did the Germans get their hands on to evaluate (answer is 'not many').

      I also note you discounted even here the two shots that bounced the same armor fired by the same gun. Apparently a sample size of one beats a sample size of two to you in indicating an expected result.

      2) and another shot went into the frontal hull hatch

      Maybe that should read 'the partially open' front turret hatch??

  10. The document does not represent an unconfirmed unit claim. Something You would be able to differentiate if you´d have any understanding of how to work with primary sources. The document is an assessment of the army intellegence service FHOst, collecting information about a new vehicle encountered in battle. The IS2 in question was investigated physically and the evidence claimed by the Pz4 crew confirmed on site, the wreckage was recovered and sent to Kummersdorf for final A/WaPrüf6 assessment.

    A later report by WaPrüf6 confirms that the KWK40 can deal with IS2 frontally and identifies the inferior resistence of cast armor as the primary reason. Official battle instructions written late in 1944 and issued by OKW to the front also attribute vulnerability of this tank vs 75mm KWK L/48 due to inferior resistence of cast armor:

    "c) neu aufgetreten: "Josef Stalin" KwK 12,2 L45.
    Er ist der erste Kampfwagen mit Mündungsbremse nach deutschem Muster. Trotz einer Panzerung von über 100mm hat die Panzerung eine geringe Festigkeit durch vermehrte Verwendung von Stahlguss.
    Alle bisher aufgetretenen englischen, amerikanischen und russischen Pz.Kpfwg und Sturmgesch.-Typen sind auf Gefechtsentfernung einschliesslich KwK L 48 abzuschiessen.
    Abschließendes Urteil.
    2. Alle bisher aufgetretenen feindlichen Panzer= und Sturmgesch.-Typen sind mit unseren derzeitigen panzerbrechenden Waffen einschliesslich 7,5 L 48 abzuschiessen.

    1. Right, so you trust German official instructions, but Soviet official instructions are discarded as propaganda? You're one odd duck, let me tell you.

    2. Cast armour doesnt mean weaker. As I posted above, IS-2 was knocked/perforated by hit to the lower plate (100 mm/30) at 1000-1100 m while KV-1 was fully perforated to the upper front armour (30+75 mm/30) at 1500 m. KV-1 main armour is made from rolled steel which is much softer in compare to IS as we can see some shot up exemplars.

      Lower plate is weakest point on on IS tank (at least for early version without spare track holders) and can deflect even KwK 36 stock armour piercing or at least prevent to full penetration. Here is captured one with pynthols and penetration in the turret caused by Nashorn.

  11. While the relationships between hardness, obliquity and penetrator are complex indeed, it cannot be generalized that harder armor equal more protection. The relatively high hardness levels of soviet cast armor was certainly a problem when the penetrator did not break up as it enhanced penetration of intact penetrators by adiabatic shear failure. Against such projectiles, the softer KV1 RHA armor may even have been preferable. This presumes, among other things, that none of the plates was messed up by poor attention paid to tempering temperatures in order to prevent britellness, which is not certain.

    Btw, the 75+30mm laminated array does represent only about 95mm single layer aequivalent. By WaPrüf´s own assessment, cast armor was 14% less resistent, on a thickness base, than RHA. Today, relatively similar figures are used (for cal. sized plates), in order of 15%.

    I happen to know that the bow armor was deflecting KWK36 impacts at various ranges (1200m, 100m, 700m)- but what we don´t know are the conditions in regard to target angle. The bow armor when impacted with a 40° side angle will not be penetrated by KWK36 at all -if it is from good quality. A later -soviet report CAMD RF 38-11355-2872 on IS armor goes so far to explicitely state that the IS-2´s bow armor will protect from 88mm KWK43 hits only from ranges of 5100m (when striking directly from front with 0° target angle). Mind that the 88mm KWK43 obtained a terminal velocity at 4000m in order of only 648m/s, roughly identic to the KWK36s at 1500m -with the very same 88mm Pzgr39.

    Russian assessments of IS2 knock outs are dependent on guesswork in determining the source of damage. The "FERDINAND" disabling the IS from ambush at 1100m mentioned above, f.e. was verifiedly false and represents another SPG or (more likely) a STUG because there was no FERDINAND in service on the whole eastern front in that timeframe.
    Pz4 with Schürzen more often than not were "misidentified" for TIGER in soviet after action reports. Why this common mistake shouldn´t happen when IS kills are concerned, escapes me.
    Their guesses about ranges are speculative and will be grossly incorrect unless they succeeded to interview the german crews.
    The same caveate certainly applies to the german side of the story but -unlike the soviets- they had actual records which of their own tanks was shooting / claiming a hit at what range, which narrows the source of error down to whether or not the hit/ target ID was correct. So if the disabled tank was investigated and identified by physical examination / witness / photo evidence or even sent back to Germany for further studies, we must infer that their information is accurate.

    1. It's not exactly news that the Soviets used "Ferdinand" as catchall term for all German casemate TDs/assault guns...
      Their own SU-76 received a nickname derived from that big box.

      Skirted PzIVs were misidentified as Tigers for all the usual reasons for such confusions (Tiger II's for Panthers, the Prinz Eugen for the Bismarck...) - distance, camouflage, similar profile and no convenient points of reference for estimating size. This notably led to a serious tactical misjudgement at Prokhorovka...

      Reasonably sure Soviet technicians knew how to measure the diameter of entry holes like everyone else tho.