Saturday, 25 March 2017

LPP-25: Light, Simple, and Unwanted

The light LPP-25 anti-tank gun was built as an answer to the German s.Pz.B.41 anti-tank rifle. As a result of information that reached Soviet designers from the front lines, a weapon was born that did not lose out to the German gun, but without the complex and short-lived conical barrel. What was this LPP-25 like?

The idea of a light anti-tank gun with high penetration was born in the Dzerzhinskiy Artillery Academy in the spring of 1942, when its lecturers learned of light and effective German anti-tank weapons. This information was combined with information about massed use of fast tanks, assault guns, and armoured cars with, at the very least, bulletproof armour, and the theories of the lecturers about the use of anti-tank guns in battle.

Ambitious plans

The academy's students and most of the teachers were sent to the front lines. The academy itself was evacuated to Samarkand in mid-November of 1941. The remaining teachers did not lose contact with their former students and colleagues, and proposed a new weapon based on correspondence with th front lines.

Drawing of the LPP-25 type 1, travel position.

Anti-tank guns were the main method of dealing with tanks and armoured cars. They were very effective during defenses when firing from prepared positions, but needed tractors during an offensive to keep up with tanks and infantry. If the enemy counterattacked, they did not have time to prepare convenient positions. For these reasons, the use of anti-tank rifles to reinforce infantry units on the defensive and during an offensive was considered optimal. These rifles had a number of advantages: they were light, small, and had good penetration at short range. At the same time, they had their drawbacks: heavy weight for only one soldier, difficulty in aiming at moving targets, insufficient penetration at ranges past 300 meters.

As a result, a project was created to plug the gap between an anti-tank rifle and a medium anti-tank gun: a light anti-tank gun, capable of keeping up with infantry. The main opponent of this gun would be light and medium tanks, armoured cars, regular cars, and enemy strongholds. The larger caliber would improve penetration and the mount would make it easier to aim at moving targets. The s.Pz.B.41 conical barreled anti-tank rifle influenced the development, as it was ideal for that role.

The project's main author was Engineer-Lieutenant-Colonel A.N. Sidorenko. Engineer-Captain M.F. Samusenko and Engineer-Captain I.I. Zhukov worked alongside him. They composed tactical-technical requirements for a weapon which was presented to the department of artillery. After a long discussion, work on the project was approved.

Drawing of the LPP-25 type 1, battle position.

The 25 mm caliber was chosen for the gun, as it was optimal from the point of view of compactness and overall weight, but allowed for penetration of over 35 mm of armour. The gun was designed to use as many parts from guns that were currently in production as possible.

The ammunition was new, but made with existing components. The 295 g AP shell was taken from the 25 mm AA autocannon mod. 1940, and the casing was a necked-down version of the 37 mm mod. 1930's round. The muzzle velocity of 1200 m/s was expected. The overall weight of the gun was limited to 230 kg.

Seems that the designers of the project, indexed LPP-25, had the opportunity to familiarize themselves with the ammunition for the s.Pz.B.41, and not just the gun itself. A special 25 mm shell with a tungsten core was proposed, similar in size to the one in the German shell. The argument was that the USSR already produced tungsten cores for 12.7 mm bullets and a slightly larger core would not be an issue. The mass of such a shell was 200 grams, and the muzzle velocity would increase to 1400 m/s.

Barrel of the anti-tank gun.

Since the tungsten core shell would be expensive to produce, it was assumed that the ammunition loadout would contain no more than 25% of these shells and that they would be used only in special circumstances, such as when enemy heavy tanks appeared less than 300 meters away and all regular shells were expended.

Calculations were also done for a shell analogous to the German s.Pz.B.41. In this case, the muzzle velocity increased to 1700 m/s and the penetration would have been 1.5 times higher. The calculated penetration of the LTT-25 with any shell was higher than that of its German equivalent.

The barrel and breech of the gun were developed in April of 1942. The overall project was finished and approved in May, at a special meeting with the academy's dean. After that, the blueprints were passed on to the People's Commissariat of Armament for production.

The barrel and breech were built at the Molotov factory #172 in Motoviliha, a suburb of Molotov (within modern day Perm). Since the factory was busy with production of the 45 mm mod. 1937 gun and tasks connected with the M-42 and M-6 guns, it took some time to fulfill the academy's request. Only a long string of letters and personal involvement of GKO member L.P. Beria in October of 1942 managed to get two barrels and two breeches produced and sent to factory #702 in Tashkent.

Left: the shell from the 25 mm mod. 1940 AA autocannon in the shell casing from the 37 mm AT gun mod. 1930. Right: LPP-25 type 1 AT gun in travel and battle position.

Factory #702 developed working blueprints and assembled two experimental prototypes on different mounts and with different barrels. Some parts were built by warehouse #20 in Tashkent. Thorough cooperation was required, and production was faced with many difficulties, mostly because of lack of communication. This delayed production.

Both guns were delivered to the academy in January of 1943. A commission inspected the prototypes on January 30th and tried out the first prototype. Due to a lack of an artillery proving grounds or proper gunpowder, a limited amount of trials was performed.

Calculated penetration of the LPP-25 depending on distance and angle of armour:


100 m
Up to 75
400 m
500 m
600 m

Variant 1: steel shell, V₀ = 1200 m/s, mass = 295 g
Variant 2: special shell, V₀ =1400 m/s, mass = 200 g
Variant 3: special shell 28/20, V₀ = 1360 m/s, mass = 123 g

Description of the LPP-25 type 1 anti-tank gun

  • Caliber: 25 mm
  • Practical rate of fire: 20-25 RPM
  • Vertical range: -7 to +11 degrees
  • Horizontal range: 30 degrees
  • Aiming speed: 
    • Horizontal: 6° per second
    • Vertical: 2°24' per second
  • Bore axis height: 300 mm
  • Clearance: 300 mm
  • Wheel base: 1080 mm
  • Mass: 240 kg
  • Time to convert from travel to battle position: 8-10 seconds
  • Dimensions in travel position, LxWxH: 3500x1250x1060 mm
  • Dimensions in battle position, LxWxH: 3300x2020x800 mm
  • Top speed: 60 kph
  • Number of parts without wheels or sight: 402, 32 of which are borrowed from other designs
The gun was made up of five assemblies:
  • Oscillating part
  • Upper mount with elevation and turning mechanism
  • Lower mount with wheels, suspension, and trails
  • Shield
  • Optical sight
The oscillating part included the cradle, recoil brake, monobloc barrel with 12 rifling grooves (34 caliber twist), 2525 mm in length (L/101), connected with the breech, the direction case, the retaining nut, return mechanism, and muzzle brake. The breech was taken from the 37 mm AA autocannon mod. 1937 with some minor changes.

Conversion of the LPP-25 from battle position to travel position. The project's authors are likely pictured.

The upper mount contained the elevation and horizontal traverse mechanisms, which were similar in design to "classical" anti-tank guns.

The pipe-like trails with travel locks were attached to the lower mount with ball joints. The lower mount was built as a platform with the wheels, suspension, and trails.

The wheels deserve special attention. Mounted on a cranked axle with a winch and leaf springs, they were taken from the TIZ AM-600 motorcycle, but with a solid tire. The shape of the axle raised the wheels in battle position, and the lower mount rested on the ground on a special spade.

The shield was 3 mm thick, had an irregular shape, and was sloped at 30 degrees. The shield was designed to protect the crew from pistol caliber bullets and light shrapnel. The shield could not deflect a rifle bullet at close range.

Aiming flywheels of the LPP-25 type 1.

The "duck" type optical sight was original, and had 3x magnification and a FOV of 12 degrees. It was designed to fire at a range of up to 1000 meters without raising the gun.

Firing trials showed that the muzzle velocity was less than calculated: 1165-1180 m/s instead of 1200. Nine shots were fired at the 465. mm rear hatch of a T-34 from 140 meters at 90 degrees. Two hits registered, one in the side, making a penetration with a fragment knocked out, one in the center, making a clean penetration.

It turned out that the muzzle brake, designed like the German s.Pz.B.41 muzzle brake, was too effective, at three times better than calculated. This caused short recoils, and the semiautomatic mechanism either worked poorly or not at all. The muzzle brake was safe and did not stun the gun crew. It was decided that using this muzzle brake design on other guns was reasonable.

Rear hatch from a T-34 tank after being shot with the LPP-25 gun.

The gun turned out to be stable when firing with the barrel in any position. This was achieved because the mount rested on the ground in battle position.

The gun was easy to move across cross-country terrain with the strength of the crew alone. The small weight and size allowed it to fit inside the truck bed of a ZIS-5 truck and many others. A proposal was made to simplify the design by removing the suspension. That way the gun could fire from its wheels.

LPP-25 anti-tank gun, type 2

The second variant of the gun had significant differences. The barrel, designed for shells with a muzzle velocity of 1400 m/s, had its rifling twist at 45 calibers, as opposed to 34 calibers with the first type of gun. There was no traverse mechanism. Aiming was done in the same way as on the s.Pz.B.41, with the gunner's right hand pulling on a handle attached to the cradle. The handle also housed the firing mechanism. A ribbon brake was used to regulate the aiming sensitivity which was used for precise aiming (for example, at the firing port of a pillbox).

The shield attachment was simplified. The wheels were removable, and had handles for transport. The box-like trails were similar to early s.Pz.B.41 trails. The optical sight was different, the PP-9 model.

LPP-25 type 2 in battle and travel positions.

The LPP-25 type 2 was assembled from 375 parts, not counting the sight or wheels, 32 of which were already in mass production.

After trials, the academy commission concluded that the LPP-25 was a modern artillery system that could become a good anti-tank gun to support infantry and tanks. The commission concluded that the gun could be installed on an SPG, used in airborne units, was simple and safe to use, and had significant reserves for simplification. The ammunition could be put into mass production quickly. The commission deemed it necessary to send the gun to proving grounds trials.


On February 6th, 1943, the dean of the Artillery Academy, Major-General S.P. Sidorov, sent documents regarding the design and trials of the LPP-25 to the Deputy People' Commissar of Defense, Marshal of Artillery N.N. Voronov and GAU Chief Colonel-General N.D. Yakovlev with a request to perform trials.

On March 30th, 1943, a decision was made by the Chief of Staff of Artillery, Major-General of Artillery F.A. Samsonov, that if the drawbacks of the LPP-25 were resolved, it could be accepted as battalion or even regimental level artillery.

The LPP-25 began trials at the Gorohovets proving grounds in early July of 1943. Three types of shells were made: light subcaliber (163 grams), regular steel, and a tungsten core round.

Firing from the LPP-25 type 1.

Aside from trials against armoured plates and stability trials, the light subcaliber shell was used against a captured German tank "medium in weight and heavy in armament" (likely a PzKpfw III) from a range of 100 meters. The gun was aimed at the 45 mm thick upper and lower front plates. The results were all complete penetrations.

However, not all calculations were correct. For example, it took 20-30 seconds to convert the type 1 gun into battle position, and 26-45 seconds to convert it back. The mass was also a bit higher than expected at 277 kg. The width of the shield was insufficient, it was uncomfortable to aim, a lack of recoil guard meant that the crew could sustain injury when firing, and the sight markings were poor.

A number of improvements followed, including the gun shield.

The second round of trials took place during September and November of 1943. The trials found the type 1 gun superior, under the condition that newfound defects be resolved.

Improved gun shield for the LPP-25 type 2.

The penetration of the LPP-25 was established as follows:
  • The stock AP-T shell from the 25 mm AA autocannon mod. 1940 (286 g) penetrated 45 mm of armour at 60 degrees from a range of 340 m.
  • The experimental light subcaliber shell, German type (167 g) could penetrate 60 mm of armour at 60 degrees from 500 meters, 75 mm of armour at 60 degrees from 65 meters, and 90 mm of armour at 90 degrees from 200 meters.
  • The experimental subcaliber shell from the 25 mm AA autocannon mod. 1940 with a tungsten core (200 g) could penetrate 60 mm of armour at 60 degrees from 400 meters, 75 mm at 60 degrees from 115 meters, and 90 mm of armour from a range of over 190 m, but less than 300 m.
The lifespan of the barrel was 600-650 shots.

Even though the gun showed satisfactory ballistic performance, satisfactory precision, good maneuverability and low visibility on the battlefield, simplicity of service and sufficient penetration, it was not adopted into service. The 37 mm ChK gun designed by E.V. Charnko and I.A. Komaritskiy was chosen instead.

The LPP-25 gun was an excellent light gun, suitable for mid-WWII. It was an excellent example of how to achieve impressive penetration with a small caliber using simple technical solutions.

Original article by Vadim Antonov.


  1. Observtations:

    [A] the data for penetration of sPzb41 are grossly in error and reflect soviet calculation, not actual performance.

    [B] during the trial shot against the 45mm cast(?)armor hatch of the T34 at perpendicular, none of the impacts was flawfree.

    1 impact penetrating too close to a drill hole, where resistence is expected to be inferior (less than three calibre to the next unsupported plate edge). Some spalling effects have to be reckoned with and are normal due to use of uncapped AP

    2. one impact is at the unsupported plate edge, agains where the armor can be expected to be inferior

    This does not indicate that the 25mm could defeat 45mm cast (?) armor at 140m distance from 90° in a flawfree impact.

  2. If you had read the s.Pz.B.41 article, you would know that the penetration data for the gun that the Soviets used was calculated. There is no grand conspiracy that you're blowing open here, but then again, reading is hard, blowing up in righteous fury is easy.

    Your righteous fury also seems to have skipped right past the part where the tests against some random junk lying at the Artillery Academy and the penetration tests against proper test plates at Gorohovets were completely different tests, but you don't seem to consider it necessary to read articles before responding to them. How long before your criticism is based entirely on the article title alone, I wonder?

    1. Why not stay within the frame of the topic? Both "penetrations" obtained holing of the plate by a specific failure mode of the plate, not by action of the projectile. The mode of failing is edge effects in one (plate edge fragment broken off, nose not penetrating through fragment), and plugging, assisted by a too close hit to a drill hole in the other. From the photos of the fragments it is clear that in neither case did the projectile itselfe penetrate. It only punched out a plug and mushroomed itselfe against the plate, thus failing.
      A higher quality projectile may have penetrated entirely and cause a ductile plate to fail by a different failure mode: Petalling, which for 1.8 cal/thick (for the 25mm AP) is to be expected unless there is some britellness caused by excessive hardness or inferior heat treatment (temper britellness) is involved.

      Neither penetration would be counted as "Durchschlag" under german definitions (by german standarts penetration would be rated below 45mm unless ten times in a row -for this calibre- complete and flawfree penetrations were obtained). It should be noted that cast armor was considered by the soviets themselves 20% to 25% less resistent than RHA (depending on thickness, in this range).

      Thus, penetration at 140m would be at or less than 45mm cast at 90° with steel AP instead of the expected ~70mm RHA. A serious shortfall in penetration performance.

      It appears possible to me that the soviet calculated penetration baed upon a projectile quality, which they were not obtaining from production. But I have hinted to this point already a couple of times before.

    2. I'm consistently impressed by your ability to make conclusions better than actual specialists who have access to infinitely more information than you do. Your talents are squandered as a blog comment troll, think of how many great historical mysteries you could be solving. Or you can try your hand at espionage, the possibilities are endless.

    3. I have primary source evidence for what I state. I can´t say the same for Your blog...

    4. Really, you have the GAU penetration tests from the Gorohovets proving grounds? Please share, I would love to see them.

  3. You might not be aware of it but some of the photographs shown here have to be considered primary sources. That includes, among others, those of the 45mm cast armor hatch, which were holed but not penetrated by the 25mmm AP from close range. Under conditions which allow assessment. Other trials may differ, but the conditions are not known. F.e. the soviet preference of burned out captured vehicle armor for ballistic trial is not indicative for actual penetrative performance of intact armor due to the secondary heat treatement affecting the plate. You blog does not differentiate this, in part because to mud the water and in part due to simple lack of basic metallurgical knowledge.

    Also, special trial ammunition or specially treated (selected) service ammunition may have been used.

    You would be shocked to know how many actual ballistic trial records are in my possession.

    1. Right, so actual real life contemporary ballistics specialists from the Artillery Academy are powerless to make any conclusions and had to send their gun to the GAU to get tested, but the mighty critical mass can make all the conclusions he needs from just one photograph! Do you do palm readings too?

      It's also hilarious that you're accusing me of trying to "mud the water" even thouh I explicitly state that the PzIV in the one test was burned out before the test. There is no other vehicle tested that was burned out aside from the ones in your imagination. There is no "preference" for burned out vehicles like you insist.

      Unlike you, I cite conclusions of contemporary professionals. I don't rely on phantom "metallurgical knowledge" and then assume extra conditions until my hypothesis makes sense like you do.

    2. "It's also hilarious that you're accusing me of trying to "mud the water" even thouh I explicitly state that the PzIV in the one test was burned out before the test"

      What a hilarious lie is that, Peter? You only admitted it was burned out, after I pointed You directly to the fact. In the article, You fail to mention that the soviet prooving ground subjected burned out armor plate to ballistic test. There is only a vague reference, that the Pz IV was "badly beaten up", not that it was burned out. To suffer a penetration or two is not the same as beeing burned in terms of how it changes the resistence of armor due to inducing britellness from secondary heat treatment and air cool. That´s understood by everybody
      with at least BASIC metallurgical knowledge - a key sensitivity solely missing by the authors of these articles.

      Contrary to the tabular listing of this article, the experimental 25mm gun with soviet ammunition was not superior to the service PzB41 with it´s ammunition in penetration. And considering contemporary anti-tank experimental ordnance equipment, by the time the soviets played with the 25mm and struggled to reliably penetrate 45mm cast armor at short range, the germans tested Wgr.-Pz HL. 66mm "Schiessbecher" for 20mm guns, which were able to penetrate frontally anything the soviets could throw at them, eventually obtaining a penetration in excess of 180mm RHA @30°, independent of range obttained 1943 with straight cone. The more elaborate and later ones with shaped cone tested in summer and autumn 1944 had the capacity to go frontally through IS3 turret or pike nose with penetration in excess of 250mm RHA @ 30°...

    3. Because overcaliber HEAT munitions are at all comparable with kinetic penetrators right.

      Also those things weren't... exactly a roaring success if memory serves, just gave badly obsolete light AT guns at least a theoretical chance to still be useful against serious ironmongery.

      Chalk. Cheese. Why are you even comparing the two?

      Also, 250mm at 30 degrees what. Isn't that equivalent to like 500mm plus flat plate?

    4. They are for handheld weapons in anti tank role. In that role, the 25mm was obsolete from the begin and did not meet modern requirements.

      And in turn of HEAT penetration, You are mistaken. Penetration for HEAT at 30° was 100%. For HEAT, penetration at 0° was only 105%, penetration at 60° was 80%. Penetration of HEAT warheads was highly variable and greatly dependet on the ideal standoff distance, liner geometry and design. Unlike AP, the variances resulted in a large spread between individual results, so that the service "reliable" penetration was considerably below average penetration).

      For whats worth, the following thicknesses of RHA armor plate were defeated at 66mm standoff distance (=1cal) using the design P H=1/3 during trials:

      These trials convinced that no practical armor thickness could prevent HEAT from penetration, and effectively ended the MAUS and related project developments.

      Compare: BA/MA RH8-v.277, Bericht Nr. 146, Untersuchungen an der 6,6cm Schießbecher Granate zur Steigerung der panzerbrechenden Wirkung, dated 16th of oct. 1944 (classified SECRET)

    5. You pointed me to the fact in the article... Which I wrote. How delusional are you? I mean it's one thing to claim to know more than an entire proving grounds worth of professional staff, it's another thing to claim that I don't admit something that I myself wrote.

    6. perhaps, next time before jumping to conclusions in regard to penetration of tank armor, You should consider mentioning that the trials are worth NOTHING due to the use of burned out tank targets.
      It´s actually fairly proper to cast in doubt the prooving grounds professionality when such practices are conducted. I mean, I can perfectly understand if a combat unit is doing this but a prooving ground establishment? Wow, that´s a downer, for sure.

    7. I am not jumping to conclusions. I am citing the findings of contemporary experts. You choose to ignore their findings and instead go off some lunacy of your own creation. I can't imagine how anyone can have an ego of that size that they consider their opinion more worthwhile than a whole cadre of professionals.

      Also the PzIV tests and these tests were done in different places, but such pesky details don't concern you, as usual.

    8. What lunacy? To point out that they used invalid targets on the prooving ground? Any historian should be interested in it and ask why one would invalidate a whole test with such unprofessional practices.

    9. Yes, how dare they perform a test while accurately recording the conditions of the test! So unprofessional, I tell you what.

    10. This got started in '42, the whole evolution of rocket-based portable AT weapons had barely taken its first steps. Plus the gun was meant as a "cheap and cheerful" counter to light armoured vehicles, which were and are a *rather* more common headache than full-blown tanks.
      And given that even the big 8-wheeler SdKfz 234 topped around 30mm plate thickness the performance oughta been quite "good enough" for the weapon's intented purpose...

      As for those penetration numbers, uh-huh. Kinda... *fantastic* figures for a mere 66mm hollow charge, when actual operational designs with far larger warhead diameters such as the ~150mm Panzerfaust only rated like 200mm.

      I mean, that's claiming seriously better diameter to penetration ratios than Cold War designs from a decade plus later; you'll have to excuse some deep skepticism here.

    11. Well, there is nothing the heavy 25mm high velocity gun can do on a SdKfz 234 which the lightweighted PTRD rifle can´t do. So what´s the point in the first place?

      Also, soviet high velocity gun research and german HEAT research are contemporary: By 1942 the germans were experimenting already with the 8.8cm HEAT rocket thrower and Hl. Stielgranate.

      Notice: You refer to "rated penetration". There is a difference between service "Durchschlag", official penetration rating (= reliable minimum penetration) and those obtained at the prooving ground, which also quote "averages". For HEAT warheads the additional problem was defining what exactly constitutes a "penetration". As a matter of fact, unlike full bore or sub calibre projectiles, HEAT dissipates during acting on plate and leaves just a hole. So only the british "penetration" and the US Army ballistic limit definition (crack or hole through plate)could be applied to HEAT, not the original german definition, which required the penetrator fit to burst completely behind plate.
      However, the germans wanted to insist on having an "effect" behind plate, and thus required not only a "hole through" from their HEAT charges but an excess of hole -typically 1/4 cal minimum sized in order to ensure that enough molten metal is accelerated from the back of the plate to hit something in the compartment behind. Thus, after a test session, it was practice to cut sections from the plate and measure the depth of the HEAT penetration. The average was recorded on the prooving ground. The german service, however, only accepted the penetration if also effect is behind the plate, and consequently rated the penetration considerably lower for HEAT.

      You will understand that I don´t want to reproduce the whole report here (I have given the archival signatures, already) but the following page from the report compares the service 66mm Hl.PzGr. (right, with one failure marked with x) with the improved, experimental type studied 1943 and 1944 at various standoff distances:

      I happen to know that "200mm rated" PzFst penetrated frontal glacis armor of TIGER2, too.

    12. Pretty sure a high-velocity 25mm gun can get results against light AFVs from a rather longer range than a 14.5mm rifle you know. And as a bonus can serve as a light infantry gun against strongpoints and suchlike - this also being the double duty that the 20mm AT rifles like the Finnish L-39 "Elephant Gun" pulled.

      And around '42 was exactly when man-portable rocket launchers were taking their very first steps, namely the "Bazooka" and the derived "Panzerschreck". And the Stielgranate obviously had fuck-all to do with rocketry (and was impractical as Hell in practice, but beggard can't be choosers).

      Obviously nobody is going to much care for any HEAT result that doesn't actually do something meaningful behind the plate, why are you even bringing that up. Mere dents and gouges don't much count for kinetic penetrators either, aside from the spalling that might cause.

      Anyways. 66mm would be the caliber of for example the Seventies-era M72 LAW which the US military rated for 200mm RHA penetration (which would be more or less the same as what the wartime Panzerfaust gets rated for with over twice the warhead diameter), just to give a point of reference. While the IS-3 hadn't been relevant for a few decades by that time I'm pretty sure the 'Mericans wouldn't exactly have been supremely confident about trying to get through that level of armour with that thing... especially as that oughta been exactly the kind of thing the design of the tank was supposed to be proof *against*.
      So, again, maybe adjust your hyperbolic claims about a never-operational wartime first-generation warhead design accordingly?

    13. Yes, the 25mm can penetrate at longer ranges than the 14.5mm presuming it can hit something at longer ranges. This caveat shouldn´t be underestimates because the accuracy in the first trial for which we have quantified data, was very poor. Only 2 out of nine shot fired at 140m distance managed to hit a 0.47m diameter target. This translates to a 50% zone of roughly 1.0m and a total dispersion of roughly 4 metres at 140m -about as bad as a PzFaust. The dispersion was found to be better during the 2nd trials but there are considerable problems with such high power, lightweighted and low life guns in sustained accuracy (noticable drop of accuracy after some shots were fired). The soviet use of rather hot propellent, and the very high muzzle velocity further aggrevates this problem. You can´t circumnavigate physics!

      In the end, very high velocity guns can work -but not with the ww2 soviet AP ammunition. In order to produce optimal penetration, the AP bullet needs to be strong enough not to deform at impact, a problem which is considerably more difficult under high impact velocities than at low or moderate ones. Soviet uncapped, low grade steel AP-shot is the LEAST desirable AP-bullet type for high impact velocities as it breaks, and shatters with east (look to the two impacts of 25mm vs 45mm hatch). It requires instrument grade steel, with decremental heat treatment and protected by an armor piercing cap to extract optimum performance. The soviets during ww2 were not willing to change to instrument steel for AP ammunition but after the end of ww2, even they eventually consented with trial results and dumped their wartime APBC ammunition designs in favour of german Pzgr.39 series APCBC-HE ammunition types.

      In terms of Armor penetration, again Your statement is in conflict with primary sources. Both, the UK and US thorough ww2 used a penetration criterium which did not require to have any effect behind plate as long as a hole was made entirely through the plate, however small. So yes, it´s worth to know and care for these little details.

      And finally, Your characterization of the IS-3 "especially as that oughta been exactly the kind of thing the design of the tank was supposed to be proof *against*."
      are completely in error. The IS3 was not designed to be proof against HEAT charges. That was not even on the agenda by then.

    14. Right, so yet again the powerful clairvoyant abilities of the great critical mass are superior to a fully equipped proving grounds full of qualified personnel. Behold as he writes a complete and thorough analysis of the weapon based on a photograph! Who even needs expensive testing procedures and large proving grounds that take up lots of space, send this wunderkind to do the job in seconds that a whole cadre of experts can only do in days!

    15. Who can take such silly comments and articles serious, Peter? I certainly can´t. Instead of trying to cover Your own faults by embarking on yet another futile campaign of sarcasm, I suggest strongly that You start to comprehend. Educated people can qualify a projectile shatter from impact photo records when both, the plate and the plate fragments are photographed from both sides with projectile remains shown, too. That You are unable to recognize it is Your fault, not mine. And that´s not something special, it´s in agreement with other prooving ground data on wartime SOVIET AP vs german RHA, or naval AP on armor plate tests, which I own a couple of thousends of individual impact records, sufficient to form an educated opinion to say the least. Finally, the lack of willingness to change from soft 35 HGS to a proper AP steel is proven from GAU KA russian primary sources, which You posted previously on this board, and is also found in wartime and postwar analysis records of captured soviet ammunition, which I own. You are the one who doesn´t understand how armor penetration works and pretends to theorize on this topic based upon half baked, uninformed and misleading presumptions.

    16. The 25mm high velocity gun required a projectile which is mhaving a tungsten core or, if full bore AP, beeing made of decrementally heat treated, high grade steel and ap-capped to be effective. The APCR type was new and the APC-type non conforming to soviet standarts. Both were expansive -not exactly the kind of ammo anyone would want to see expanded against SdKfz231 targets.

      The eventually choosen 37mm TshK was -owing to a moderate muzzle velocity- relatively effective with service soviet ammunition types (less at very short range or against very hard armor) -and on top of that, with a mass of only 209kg considerably lighter than the 277kg heavy 25mm gun. It also fired a more effective HE-shell and was smaller.

    17. Right, educated people such as, I don't know, a GAU testing team? Of course, as always, everyone else is wrong and you are right, including actual contemporary professionals with physical data that you don't have access to. But no, as your gimmick goes, all documents are fake if you say so, all historians are Putin's shills at your discretion, the only real and absolute truth is held by the one and only critical mass, to be dispensed as he sees fit to the unworthy masses.

    18. What exactly does the GAU testing team claim in Your opinion? That the 25mm perforated the 45mm hatch? Well, it didn´t by UK, US or german standarts. Or that it the projectile did not shatter, despite photographic evidence demonstrating the opposite? If that´s the information You extract then yes, it´s time to cast their education in doubt. You made up so many claims, bullshitting around and the reason for this lies in the fact that You don´t understand what You are writing about.

    19. Man, do you even read the articles you write essays in the comments of? The GAU team's findings are plainly written. The tests against the hatch were *not* done by the GAU team, as I have told you over and over again. What's bullshitting is your claims that you know more than a whole proving ground's worth of experts whose job was literally to test guns, while your job seems to be to pollute blog comments on the internet.

    20. It doesn´t change the results of the hatch test. Nor does it change the fact that soviet crappy ww2 AP ammunition was not suited for high velocity guns for metallurgical and design reasons.

    21. Well it's a good thing that the hatch test wasn't the one that the penetration figures are based on, now is it?

      Also here's something I thought of, how come you're so swift to accuse Soviet testers and engineers of deceit and incompetence when the word "German" appears in the article, but when American or British hardware is being tested you're suspiciously silent?

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