Monday, 9 January 2017

Comparative Penetration


1. As a result of trials of D-25 (122 mm) and D-10 (100 mm) tank guns, the following penetration ranges against the upper front plate of the Panther tank were established:

Distance of complete penetration
122 mm D-25
Armour piercing
100 mm D-10
Armour piercing
German 88 mm gun (Ferdinand SPG)
Armour piercing
German 75 mm gun (Panther tank)
Armour piercing
No penetration
  1. The distance of complete penetration listed for the D-25 is not the maximum distance, as trials over a larger distance were not performed.
  2. The armour piercing shell of the German 88 mm gun (Ferdinand) does not penetrate the upper front plate of the Panther tank: the impact forms a breach and the shell ricochets.
  3. The distance of complete penetration listed for the D-10 is not the maximum distance, the maximum is 1300-1400 meters.
2. The armour piercing shell of the D-25 gun (122 mm) can penetrate an 85 mm thick armour plate at 55 degrees (upper front plate of a Panther tank) from 700 meters further away than the D-10.

3. The penetration of the armour piercing shell of the D-10 gun can be increased to penetrate from 1500-1600 meters (when firing at a Panther's upper front plate) if the muzzle velocity and shell quality are increased.

4. The practical rate of aimed fire of the D-25 obtained during trials (2.5 RPM) is insufficient and is limited by the amount of time it takes to reload the gun with the two piece shell.
The practical rate of fire of the D-10 gun (7.5 RPM) is good due to the one piece shell.

5. When firing at ranges up to 1500 meters with the D-25 and D-10, fire correction is complicated by the amount of gases emitted when firing."


  1. I'm confused. The distance of complete penetration for the 8.8cm is 600 meters, but the shell ricocheted?

    1. The shell hit the sloped armour and ricocheted. The impact was hard enough to knock a hole in the armour, but the shell itself did not end up inside the tank, and thus detonation from the round didn't destroy any mechanisms or kill any crewmen. This isn't unique to this gun and tank, I've seen similar scenarios happen before.

  2. I wonder what the angle of fall of the D-25 shell is at 2000m.

    1. 1.2 degrees

    2. Thanks, it appears that angle of fall did not contribute too much to this long range hit of sloped armor.

  3. The datum for D-25 (2,000 meters) has been discussed ad nauseam in many forums, claiming that the Panther should have had defective armour plate for the round to penetrate from 2,000 meters.

    1. Then again given what state the German industry and resources were in "defective" was pretty much the norm anyway...

    2. Those sneaky Soviets, using special super-Panthers for testing German guns, but defective Panthers for testing their own! :)

  4. "(Ferdinand) does not penetrated"
    Main verb tense bro.

  5. Which projectiles were used? 100mm BP-412 or BP-412B? 122mm BP-471 or BP-471B? The terminal velocities differ significantly between those shells. Also what exactly was used as defintion of penetration? hole made? 50% of mass behind plate? 20%? 80%?
    Whether or not the plate might have been defective depends on the conditions. The performance obtained is not incredible per se.

    However, the notion that "improve in projectile quality" helps penetration at 55° obliquity demonstrates a rather poor knowledge of the armor penetration mechanics from the authors of this report. Break up actually improves penetration in this case because break up changes the headform so that ricochetting is inhibted. It´s better to have some part of the projectile penetrating than nothing at all. Compare the superior quality 88mm Pgr 39 which ricochettes off. though to be fair, break up would not have helped the 88mm nearly as much due to the smaller calibre and resultant smaller body weight. More useful against highly oblique armor would have been the 88mm Pzgr.45.

    The aspect which does improve with higher quality ammunition is penetration under conditions where break up does not occur. And the realm of those conditions where the projectile stays intact is widened in terms of velocity and obliquity. F.e. the 88mm Pzgr.39 will reliably penetrate 200mm armor sloped 30° from the normal or 240mm RHA vertical close to the muzzle that neither the 100mm and 122mm will be able to penetrate with their respective ww2 AP. I have a couple of test records with randomly selected 88mm Pzgr 39 service AP ammunition which penetrated 305mm RHA at 30° and 1280m/s striking velocity in experimental trials at the Army prooving ground in Unterlüss. A penetrative performance which was unobtainable for any soviet tank gun with ww2 AP ammunition, regardless of how much velocity You give those projectiles.

    1. The US did some post war tests of the 88mm/L71.

      3000+ muzzle velocity projectile integrity testing.

      8" (203mm) @ 0°:Two complete (NBL) penetrations with projectile passing through plate. 3124mv and 3257 mv.(550y/90y) Two ABL penetrations. Projectiles Intact. 3001 mv 3038 mv. (990y/860y)

      3 7/16" (87mm) @ 55°: Two complete penetrations. both projectiles fractured. Projectile fragments passing through plate.

      The British did 17 pdr tests on the Panther and found that it would penetrate the glacis up to 900 yards.

    2. During WWII the Russians incorrectly calculated the velocities in their firing tables. They also assumed the BR-471 and BR-471B had the same ballistics. In fact they assumed velocity of the BR-471/BR-471B at 2000m was that for 1300-1400m for the BR-471B and 900m for BR-471.

    3. Hello Mobius. How did you reach this conclusion?

    4. This comment has been removed by the author.

    5. (I'll try to post this again but it seems to disappear each time I do.)

      According to this subject the 122mm guns had erroneous firing tables up until the post wwII period when they were corrected.

      I also found that this pdf shows 1944 captured firing table that the time of flight and maximum height is considerably more than post WWII Russian 122mm firing tables below.

      This is the firing table for the 122mm BR-471B shell at 795 m/s.

      and the BR-471 shell.

      It appears the Oф-471 may have been used for the model the war firing tables.

      I'm not sure if the 1962 DDR BR-471B firing tables are entirely correct either. If you plot the 795 m/s Oф-471 to the 781 m/s DDR Oф-471 data you will see that they are more or less parallel. But if you plot the 795 m/s BR-471B data to the DDR BR-471B data you will see that they converge and cross at some point. That shouldn’t happen.

    6. Sorry Alejandro my reply doesn't seem to take.

    7. I found that this pdf shows 1944 captured firing table that the time of flight and maximum height is considerably less than post WWII Russian 122mm firing tables below.

      This is the firing table for the 122mm BR-471B shell at 795 m/s.

      and the BR-471 shell.

      It appears the Oф-471 may have been used for the model the war firing tables.

      I'm not sure if the 1962 DDR BR-471B firing tables are entirely correct either. If you plot the 795 m/s Oф-471 to the 781 m/s DDR Oф-471 data you will see that they are more or less parallel. But if you plot the 795 m/s BR-471B data to the DDR BR-471B data you will see that they converge and cross at some point. That shouldn’t happen.

    8. The spam filter caught your post. Too many links, I guess?

  6. I am not convinced that we can presume that the Panther glacis used in the test was inferior in regard to quality.

    It resisted complete Pzgr.39 penetration with 80/85mm @ 55° and 600m.
    IS3 prototype cast turret armor of somehow thicker, 90/100mm thickness was perforated by 88m Pzgr.39 at 59.2° resolved netto obliquity and velocities correponding to 1000m range.

    Nothing here indicates poor performance of the Panther glacis. It´s figure of merit compared to soviet cast armor is more than 30% more resistent for each mm thickness, factoring in obliquity and velocity differences, too.

    1. I agree, there isn’t any evidence that the Panther’s armor was compromised. British tests show the glacis hardness was around 272 BHN.

      The Pzgr 39 did not do as well against highly sloped armor than it did to vertical armor. The larger caliber Russian shells did better vs. sloped armor and not as well against vertical armor.

  7. Of course, once projectile break up occurs, all projectiles behave similarely poor, irregardless of their headshape, cap, or hardness contour. The differences are only related to if & when exactly break up occurs.

  8. Do German guns have any advantage to Russian guns? It seems they have less penetration, accuracy, caliber, and rate of fire etc. Was there perhaps better economics?

    1. Hardly. Even the British were leagues ahead of the Germans (and Continentals in general) when it came to economic mass production; the US and Soviets, being by necessity used to designing and planning for production runs on massive scales, were in a different league entirely. (And yes, many German tanks were rather undergunned for their size.)

      Reminder that by the late war the Soviets were cramming a gun for most practical intents and purposes equivalent to the Tiger's 88L56 into the T-34 without any real problems with either ergonomics or production rates.

    2. Perhaps German guns worked better as AA guns than tank guns? Were the Russian guns good at AA work also?

    3. That 85 mm that armed first the SU-85 and later the T-34/85? It was originally a heavy AA piece, just like its German peer. The 76 mm tank guns had their roots in field artillery that doubled as AT guns. The Soviets liked to design most of their ordinance (below 152 mm or so anyway) as dual-purpose.

      Can't say I'm particularly familiar with the history of WW2 Soviet AA, but it's not like the Germans were sending "Thousand-Bomber Raids" over their cities every other night either...

    4. The Soviets used 37 mm and 85 mm AA guns as anti-tank guns from the start of the war, not to mention that the L-7 76 mm gun (the one that gave birth to the L-10 and then L-11) was based on Lender's gun, an AA gun.

    5. I wonder why the Germans didn't simply use the captured guns (other than the Marders), or copy them. I know there was an attempt to copy the T-34 (VK 30.01 DB) itself but not its gun.

    6. Because they did not base their ordnance procurement plans on alternate reality internet sites. :) And that the 76 mm guns mounted on T-34 inferior to any but the short German 75mm, as far as penetrative power that is.

    7. Because the industrial logistics would have been complete bullshit, that's why. Reminder that they modified the trophy 76 mm's to use their own 75 mm ammo too in the very sensible interests of simplifying supply. (Didn't hurt that the PaK 40 propellant charge was rather bigger, what with being designed specifically for AT work rather than for dual-role field gun.)

    8. Kell,

      that´s incorrect. They manufactured german 76.2mm AP ammunition according to the Pzgr.39 specifications because the soviet 76.2mm AP ammunition was useless and inferior even to the 50mm PzGr.39 in several aspects, particularely short range vs flat plate. They didn´t modified the trophy 76,2mm guns to fire their own 75mm shells but issued new ammo instead to fire them from tryophy guns.

      However, they DID reline the captured 85mm guns to fire 88mm Pzgr rot (FLAK ammo).

  9. They do:

    A) Due to the less blunt nose shape and the hardened nose, Pzg 39 AP had substantially more penetration under conditions where the projectile stays intact
    B) a superior envelope of conditions where the projectile stays intact in terms of cal/thickness, velocity and obliquity
    C) a significantly higher accuracy (german data give deviations in rectangles matching the radii while the soviets give deviations in circles of diameters, big difference when You consider that a radius is only half as large as a diameter
    D) they carry a tiny (Pzgr 39) or small (Pzgr rot) burster charge with a reliable delay fuze causing explodion behind target plate.
    Russian projectiles did not explode behind target plate when tested but loaded AP detonated on plate or (if the plate was thin enough) while penetrating
    D) smaller claibre guns typically had a higher rate of fire
    E) russian guns used a more energetic propellant, causing more gas exposure and flash. German propellant was flashless, and firing guns were consequently more difficult to spot than large cal russian guns with smokeless (but not flashless) powder.
    F) Russian projectiles were uncapped and always had the disadvantage of insufficient strength of the projectile body, causing low order deflagrations of the fillerdue to break up striking even at normal if the plate was more than 1 cal strong.
    G) Russian (typically larger) projectiles were heavier and only a smaller quantity could be carried compared to german

    1. I agree with most of your points except ‘C’. The Russian oval deviation system is more realistic than the German rectangular deviation system. In that it assumes the x and y deviations are independent variables. Which infers there is a square root of 2 (when x=y) deviation along the 45° diagonal. That is implausible. For example if they were to rotate their gun (or target) 45° would there be a square root of 2 times deviation along one of the axis? I doubt it.

      A) As the war progressed German AP caps became more blunt and harder. Thus in this way mimicking the advantages the blunt nosed Russian projectiles had vs. highly sloped armor.

    2. Not sure what's supposed to be the point of (the second) D) since for the most part the two sides used *extremely* similar calibres - 50/45 mm, 75/76 mm, 88/85 mm, 128/122 mm... the Germans never actually used 10.5 cm guns in AFVs in any larger numbers but those'd have been firmly in the same size class as the Soviet 100 mm as far as shells went, obviously.

      Ofc as mentioned earlier the Soviets cheerfully put big guns into even medium tanks while the Germans, well, didn't so yeah.

    3. Mobius,

      The german system gave seperately horizontal, vertical, and (for long range guns) z-achses deviations. Not exactly like one rectangle but many. While the actual distribution is indeed more ovaloid, the oval system is less practical because target sleds on the prooving ground are crafted rectangular. However, in order to fall in a "german" rectangle, You had to multiply the russian 50% radii with 2. This difference has not been even mentioned on the articles published here.

      A) While the bluntness does add obliquity performance, it does so by two ways: I.) by inhibiting ricochet II.) blunter shells stay better intact

      However, the russian AP ammo was of poor metallurgical quality, partly because of inferior steel they selected (I presume on purpose), party because they had no hardening treatment. So any form on russian projectiles is of little effect during penetration, they don´t keep the form during the penetration attempt but deform and/ or break up. These shells are good at low velocity impact, ideally against high hardened armor. (guess why You often find those trials at 1000m-2500m fighting ranges...)

      German shells intended to keep their form and this greatly improved their penetrative performance. The presence of a cap helped negotiating very high impact velocities.
      While the cap is negative at 0 to 40° -unless it prevents break up-, a well shaped cap helped at obliquity impact by increasing the biting angle and by digging out a piece of the plate to make passage of whatever follows from the projectile easier. Both, the 75mm Pzgr 39 and 88mm Pzgr 39 f.e. had BETTER 55°-60° obliquity performance than the soviet 85mm blunt nosed AP (Tests vs Panther and HETZER glacis).
      German shell steel was not only of higher alloy content and thus had sufficient hardenability but also received the proper, decremental hardening treatment (nose very hard, gradually softening to the base) and a cap. People are often unaware of how soft russian AP projectiles were.
      One of the reason why impact holes in german armor are bigger lies in the inferiority of the soviet projectiles. They mushroom against the plate and don´t penetrate by piercing the plate but by punching out a plug of armor, causing larger diameter hole. This requires considerably more energy than percing action. The latter, however, requires the projectile to stay intact.

      So no, the germans did not mimic the soviets at any point. Quite the opposite, after the end of ww2, and after the soviets thoroughfully studied german projectiles and prooving ground documentation, they introduced a russianized Pzgr.39 on their own, copying the benefits of the projectile design. These are the 100mm BP-412D and 122mm BP-471D introduced in the early 1950´s...

    4. What the hell are you talking about? Soviet tables also have separate figures for width, height, and depth-wise deviation.

    5. Who said they didn´t? They just found it necessary to give the deviation in radius vs a neutral point which created a rather larger diameter area than the german rectangle based system.

    6. This comment has been removed by the author.

    7. Note 3 in this PDF shows the the Russians were defining the vertical error twice a large as the US/UK.

      So to find the error in US/UK terms you have to divide the Russian error by 2.
      US/UK and Russia defined the error as Average Mean Error which is different than the 50% error zone the Germans used.

    8. "Not sure what's supposed to be the point of (the second) D) since for the most part the two sides used *extremely* similar calibres - 50/45 mm, 75/76 mm, 88/85 mm, 128/122 mm... the Germans never actually used 10.5 cm guns in AFVs in any larger numbers but those'd have been firmly in the same size class as the Soviet 100 mm as far as shells went, obviously."

      While they did field comparable gun sizes, they did so at different times (tank guns only, ignoring the many 20mm, 37mm and 45mm guns):

      1941/2: 50mm vs 76mm & 152mm
      1943: 75mm & 88mm vs 76mm & 85mm
      1944/5: 75mm & 88mm vs 85mm & 122mm

      So yes, the german tank force relied in average on a smaller main tank gun calibre vs the contemporary soviet tank force. Just take a look at this article. Why do You think they needed to compare the penetrative performance against Panther glacis with their 100mm and 122mm vs german 75mm & 88mm guns? What´s exactly the point behind? Why don´t they include the german 128mm or the soviet 85mm?

    9. GJ forgetting the Soviets put 45 mm guns in a metric ton of smaller tanks...

      Also reminder that the 50 mm was kinda seriously struggling from the start with everything that carried the long 76 mm (the old T-28s with their howitzers can be discounted here) while the opposite... wasn't exactly the case.

      In the early years the 152 mm was only mounted in the scarce KV-2 which was an assault gun not even meant to fight other tanks and duly irrelevant to the topic. As far as AFVs went the caliber wouldn't really become relevant before the SU-152 (*also* first and foremost an assault gun) in '43.

      And the Germans didn't rely on smaller guns because they *wanted* to, they did it because their shit was bulkier and couldn't be fitted into the light to middleweight stuff that formed the factual backbone of the Panzerwaffe. The 88 mm KwK 36 vs 85 mm D-5T/ZiS-S-53 is probably the standout example; virtually identical shell weight and muzzle velocities, yet the smallest the former could be used in was the 54-ton Tiger I (IIRC attempts to mount it in the 45-ton Panther were a failure) whereas the latter merrily fit in the ~30-ton SU 85 and somewhat heavier T-34/85.

      On the same vein the 45-ton Jagdpanther carried a long 88 mm gun; the 32-ton SU-100 cheerfully drove around with a *100 mm* one... and do recall here that larger shell not only plain carries more payload which is *of some interest* with HE, but also that heavier projectiles retain their energy better at long ranges.

      You'll have to ask the doubtless long dead Soviet officers who planned this test about the choice of ordinance used. But if I had to make a guess I'd postulate the 85 mm wasn't in because it had already been thoroughly trialed previously while the German 128 mm simply *wasn't available* - Jagdtigers were a very late developement and mostly used in the West, and if they had captured examples of the towed version at hand those probably weren't of interest as this seems to have been a comparative test of AFV guns.

      And it's not like they're throwing in their own 152 mm "cat-killer" either, anyway. Were they perhaps "benchmarking" guns suitable for use in their own heavy tanks and perhaps future upgunned mediums?

    10. You seem to be ignorant of important "details" in Your comparison:
      The soviets cramped bigger ordnance in smaller hulls accepting side effects which weren´t tolerated by the german tank force:
      [1]crew discomfort
      [2]lack of bore evacuator in guns 75mm & up
      [3]lack of turret rotating platform
      [4]poor crew layout and two men turret (up to 1942/3)
      [5]very short ammo supply
      [6]poor gun depresion/elevation

      Meeting these demands required, of course, a bigger tank, as the germans were labouring as everybody else under the same laws of physics. Yeah, they instead adopted a smaller, higher velocity calibre, fired from more accurate guns, with less visibility when firing but more penetration (unless striking extremely oblique), rate of fire and effect behind target.

      It´s a conscious choice intending to preserve skilled crew force, relfecting an efficiency oriented approach. The soviets made their own. They didn´t put a lot of effort into crew protection, but then again, they didn´t invest nearly as much in crew training either. They didn´t invest a lot in quality AP projectile production either, and constantly lacked behind the germans in ordnance. However, they did compensate and arguably bridged the gap by selecting larger ordnance pieces without dealing with the required side effects at the crews expanse.

      For the record, The PANTHER wasn´t even tried with 88mm KWK36. The only 88mm they even tried fitting to the PANTHER hull was the 88mm KWK43 instead, and critisized the gun depression then but adopted this system as a platform for future development of the Schmalturm. I guess, You may want to reconsider attempting to compare the 88mm L71 with the 85mm D5T...

    11. Soviet guns of similar caliber were smaller than that of the Germans'. Compare the size of the breech of the KwK 36 to that of the ZIS-S-53.

      The two man turret was limited to light tanks and the T-34. The T-28, for example, had a three man turret and a turret platform.

      If you think that Germans avoided crew discomfort, you clearly ignored all the British ergonomics studies I keep referring to. Keep pushing that same old "German efficiency/Soviet horde" meme though! Stereotypes are the greatest argument, after all.

    12. Sorry, but I am not the guy who throws around stereotypes. Does "SS tanks" ring anything in Your head here? Do You remember the curious, to say the least, history article You have written about SS tanks at Mius? Or Your futile attempts to rewrite hitory at Prokhorovka, Bollersdorf and other sites?

      You seem also to have conveniently ignored the prime reason for heavier ordnance pieces: the german used a less energetic, slower and more even burning, flashless propellant, requiring differences in breech and chamber design. I´d rate the german gun propellent & projectile combination of ww2 superior to the Soviet contemporary ordnance in terms of ballistic trajectory, penetration performance, accuracy, rate of fire, and camouflage. Yes it´s larger and heavier, but not unnecessarely so and represents a superior product.

      And yes, the T28 had a turret platform. But then again, it wasn´t exactly a small tank, right? Which is agreeing with the point I raised, that such platforms require larger hulls.

    13. Right, no stereotypes, all you do is comment on every post saying that all historians are wrong and you are right :)

      I'm not ignoring anything, I am stating that the KwK 36 gun breech was bigger. Your assessment of German propellant as superior doesn't affect the fact that the Allies managed to fit guns with equal penetration into medium tanks that weighed half as much as the Tiger. One of them even managed to include a turret platform that you love so much!

      The T-28 was a large tank because it included two machinegun turrets in addition to the main one.

    14. Yeah, and You still fail to understand how gun construction, propellant and projectile influence breech design.
      And no, the (western) Allies didn´t had flashless powder either.
      The M4 Firefly had the penetration but didn´t had the protection offered by either PANTHER or TIGER. So yes, it was lighter because of that.

      Do You really want to ride a dead horse further? Comparing an M4 17pdr. with, say, a PANTHER, which isn´t twice as heavy but mere 21% heavier and offers significantly better frontal armor?
      Or a M4 17pdr with a TIGER 1, which has superior HE, and superior all around armor, and yet, isn´t TWICE as heavy as You mistakenly believe but only 1.53 times heavier?

      So, please Peter, where exactly is Your ww2 allied medium tank which offers the TIGER-I´s KWK36 gun performance (preferably also it´s armor protection) at only 27t?
      Or can we expect You to confess that You just made up this claim again?

      And yes, I am damn right to critisize Your articles when I take the trouble to go to an archive and have to realize based upon primary sources that You made it up. If You call Yourselfe an historian, feel free to but don´t expect me to fall on my knees. Beeing a historian myselfe actually has the benefit of knowing how many mistakes are made by them.

    15. You take the trouble to do nothing. You claim to be "too busy" to provide any information, and yet here you are endlessly trolling my comment section time and time again.

      Why are you bringing up the Firefly? Other tanks exist other than the Firefly. The T-34-85 for example. The Finns compare the penetration of the KwK 36 and the ZIS-S-53, I have the document on here.

    16. "-- allied medium tank which offers the TIGER-I´s KWK36 gun performance (preferably also it´s armor protection) at only 27t?"

      ...what the fuck kind of depraved lunacy did I just read. Get out.

    17. Kell,
      It´s Peters lunatic claim, not mine! I question the validity of his claim (correctly so, I have to add.)

      "Your assessment of German propellant as superior doesn't affect the fact that the Allies managed to fit guns with equal penetration into medium tanks that weighed half as much as the Tiger." -Peter Samsonov

      So yeah, the KWK 36 armed TIGER weighted what? 54t. Peter claimed that the allies fit guns with equal penetration on half of that, which is, 27t. And we both know this is complete nonsense!

      The T34-85 has not the same penetration as the KWK 36, unless You select a very unique set of conditions. More important, it is of inferior accuracy. And, no, the T-34/85 is not half the weight of the TIGER-I. The TIGER is only 1.7 times heavier.
      Lets not forget that the TIGER had a turret platform, had a bore evacuator, had sufficient ammo load and also had more armor all around to justify the weight differences.

    18. Yeah, I think we're done here.

    19. No self reflection, as usual. The whole methodology by comparing gun size and vehicle weight was nonsensical, if You decide to ignore all aspects but select only two.

      On a limit, one could even go so far stressing that in terms of reliable short range penetration, the 75mm L48 firing either Pzgr 39 or Pzg40/43 didn´t lacked behind the D5T firing it´s ww2, AP, APBC or APCR.
      Yet they managed to cramp that gun into a much lighter vehicle than the T34/85.

      Of course, the P4F2-J was a less capable vehicle than the T34/85 in many other aspects, which is why all factors need to be considered if meaningful conclusions are to be drawn..

  10. That has nothing to do with tank guns Mobius.

    122mm here:

    R100 & R50 refer to 50% and 100% catching radius. RADIUS is not zone. Note that only R50 x 2 is identic to the german "zone 50". Both are defined with the requirement that the zone or radius, respectively will catch 50% of the shells.

    The russian system does not use "mean" dispersion but catchant No. It´s possible, and even probable that they use a "Mean" to average different shooting results, though. For the example in question, the mean dispersion would have been 0.32m radius(!) at 1000m and 0.92m (!) at 2000m (or roughly the the shooting table dispersion at 1000m and 1.5 times that of the tabulated dispersion at 2000m). German zones are not similar to these figures. Instead of only one half of a circle, the zone defines the full rectangle, which will catch 50% of the shells. A basic question of geometry...

  11. I hope Peter can back me up on this.
    срединныe отклонение means median dispersion.

    1. Deviation, not dispersion.

    2. If you want the exact description of how the Soviet system works, here's an artillery textbook

      Figure 239 shows what срединное отклонение is.

  12. So it looks like the US translation of captured Russian firing tables (FT-F-50) have mistaken 'срединныe отклонение' for 'Mean Deviation'.
    Mean deviation has a different meaning than median deviation. 1.69 times the mean deviation converts to the 50% probability zone.

    But it should be 'Median Deviation'. Median deviation means here probable error (w). Two times the probable error converts to the 50% probability zone. It looks like Critical Mass is correct.

  13. It appears like they used the 88mm PzGr. 40 when shooting the Panther tank since the 88mm PzGr. 39 should have no problem penetrating the front of the Panther even at 1km and more.
    The question is if that was intentional or not.
    The logic could have been "if we fire this special round with improved penetration and see how well it fares, the default round must surely be worse". Since the Soviets hardly used APCR rounds at all and only with rather small penetrators, it's likely that they didn't know that APCR performs worse against sloped armor.
    At 600m the PzGr. 40 was barely enough penetration to penetrate 80-85mm at 55° which would explain why it was not able to penetrate completely.

    1. PzGr.40 is referred to as armour piercing subcaliber at all times. Testing of PzGr.40 for the 7.5 cm KwK 42 was done extensively, the Soviets were aware of the difference between it and PzGr.39 and their properties.

    2. Maybe, but the results just seem to fit too perfectly.
      I've created a slope armor calculator and the results are basically the same as stated.
      The 122mm BR-471B APBC shell defeats 80mm at 55° at around 2000m when also considering the descent angle.
      The 100mm BR-412 AP round defeats the plate at around 1200-1300m.
      The 88mm PzGr. 40 defeats the plate at around 600m.
      The 88mm PzGr. 39/43 defeats around 107mm of armor at 55° at 300m.
      This is also indicated by firing this round against the armor of an IS-3 ->

      Considering how easily the front plate was defeated by the 122mm AP round it's clear that at least parts of the armor was made of rather brittle high hardness armor that is easily defeated by large shells. Against undermatching shells the armor still be rather effective.
      Curiously both shells needed around the same momentum per area to defeat the front plate.