Rare T-70

Here's a pretty standard photo of some tanks being shipped by railroad.

But wait, what is this? Zoom, enhance!

It's a T-70. But no ordinary T-70! It's a very rare T-70 with a cast turret. Only three such turrets were made. The turret was discovered to be inferior to the welded one, and no one had the resources to develop (or even produce) a better version. 

The tank was originally to be manufactured with a cast turret designed by Dedkov, but it was replaced with a welded one before the tank entered production.

World of Tanks History Section: Type 89

In 1927, the Osaka Rikugun Zoheisho arsenal began construction of the "#2 light tank" (Type 87). After trials, the Japanese decided that the tank needs more armour and firepower. The design was completed in 1929, and resulted in the medium tank #2589, or "Type 89 I-Go".

The Type 89 had a classic layout: driver's compartment in the front, fighting compartment in the center, engine in the rear of the vehicle. The hull of the I-Go was riveted, and, at least on initial vehicles, was a re-built Vickers MkC hull, also tested by the Japanese at the time. The turret, also riveted, was equipped with a 47 mm, and later 57 mm, gun. The turret was turned manually. The I-Go also had two machine guns, one in the front of the hull, and one in the back of the turret.

The Type 89 had a Daimler gasoline engine. Later vehicles used a domestic Mitsubishi engine. The tank could accelerate to 27 kph, and had a range of 160 km.

The first I-Go tank was built in 1931. The main producer of the tank was the arsenal in the city of Nagoya.

Soon after entering production, the Type 89 received a turret upgrade, with a commander's cupola and rear bay for the machinegun. This variant is known as Type 89A.

In 1935, after experience in Manchuria, the tank was modernized. The tracks were replaced with sturdier ones, with smaller track links, the front hull plate was improved, the observation devices were better protected. The commander's cupola grew in size, and the gun mantlet changed shape. This vehicle was indexed "Type 84B Otsu". The Otsu was mainly produced by Mitsubishi. Type 89A and Type 89B tanks were used by the Army and special landing groups of the Imperial Navy. Production continued until 1937, when they were replaced by the Type 97 Chi-Ha medium tank.

Original article here.

World of Tanks History Section: Soviet-Japanese War

1. Introduction

In February of 1945, at the Yalta conference, the USSR promised to declare war on Japan three months after the defeat of Hitler's Germany. In exchange for this aid, the Soviet Union would gain Sahalin and the Kuril islands, lost in the Russo-Japanese war of 1904-1905.

At that moment, Japan and USSR had a neutrality pact, signed in 1941, lasting 5 years. In April of 1945, the Soviet Union declared a one-sided annulment of the pact, citing Japan's alliance with Germany and military action against allies of the USSR. “In this situation, a neutrality pact between Japan and the USSR has become meaningless, and there is no point in prolonging it,” claimed the Soviets. The sudden annulment of the pact sent the Japanese government into a panic, and for a good reason. The war situation was becoming critical. Allied forces dealt a series of crushing blows in the Pacific theater. Japanese cities and industrial centers were constantly bombed. No reasonable person remained in the Japanese government that believed in victory. The only remaining choice was to tire out the Americans until acceptable conditions for surrender can be negotiated.

America understood that a victory over Japan would not be easy. A handy example would be the battles for Okinawa. Japan had 77 000 soldiers on the island. America sent 470 000 against them. The island was taken, but America lost 50 000 soldiers. The Minister of Defence estimated that a final victory over Japan without the involvement of the Soviet Union would cost one million killed and wounded.

A declaration of war was handed to the Japanese ambassador at 17:00, on August 8th, 1945. It declared that combat will start the next day. Considering time zone differences, this left the Japanese effectively one hour before the Red Army marched into battle.

2. Resistance

The Soviet strategy included three stages: the Manchurian, South-Sahalin, and Kuril. The first stage was the largest and most important, and it deserves a detailed description.

The Kwantung army, led by General Otsudzo Yamada, opposed the USSR in Manchuria. It contained about one million soldiers, over 6000 artillery and mortars, about 1500 planes and over 1000 tanks.

The Red Army started the operation with a pretty significant numerical advantage: 1.6 times as many soldiers, 5 times as many tanks, 10 times as many artillery pieces, more than 3 times as many planes. The advantage was not only quantitative; the Red Army's machinery was significantly more modern and powerful than that of the enemy.

The Japanese understood long ago that a war with the Soviet Union is unavoidable. For this reason, they created numerous fortification regions. Let us examine one of these: the Hailar region, which was to counter the advance of the left flank of the Trans-Baikal Front. Reinforcements were built up for 10 years. In August of 1945, it consisted of 116 bunkers, connected with concrete trenches, and a large amount of defensive engineering structures. This region was held by a division of soldiers.

It took several days to drive the enemy out of this region. This does not seem like a long time, it's not like the troops were stuck for months. However, in this time, other sections of the Trans-Baikal front moved forward as much as 150 kilometers. By the standards of that war, the delay was significant. Even after the main forces of the Hailar region surrendered, separate groups of Japanese continued to fight, showing fanatical bravery. Soviet reports constantly mention soldiers that chained themselves to their machine guns in order to prevent retreat.

Among the Red Army's successful operations, one must pay special attention to the 350 kilometer march of the 6th Guards Army through the Gobi desert and Hingan Mountains. The peaks of Hingan seemed an impenetrable barrier for tanks. Soviet tanks traveled on a road as high as 2000 meters above sea level, on slopes as steep as 50 degrees, forcing the tanks to zig-zag. Conditions were further complicated by nonstop rain, impassable mud, rushing mountain rivers. Regardless, Soviet tanks moved forward. By August 11th, they passed through the mountains and found themselves deep in the rear of the Kwantung army, on the Central Manchurian Plains. The army was lacking fuel and armament, and had to be supplied by air. 900 tons of tank fuel alone was supplied. As the result of this incomparable feat, the Red Army managed to capture 200 000 prisoners, and a large amount of guns and armour.

The First Far-East Front of the RKKA was met with brutal resistance from soldiers entrenched on hills designated “Sharp” and “Camel”, which were included in the Hotou fortified region. The approaches to those hills were swamps, scarred with small rivers and streams. The slopes were covered in trenches and barbed wire. The Japanese carved hardpoints into the mountain granite. Bunkers were covered in concrete up to 1.5 meters thick.

Defenders of “Sharp” rejected all offers for a surrender. The Japanese commander beheaded the local villager used as a translator. The Japanese were always unwilling to negotiate with the Red Army. When Soviet soldiers breached the fortifications, they discovered no remaining people, only corpses. Among them were not only men, but women, armed with grenades and daggers.

In the battle for the Mudandzyan city, the Japanese actively used suicide bombers. They threw themselves on Soviet tanks and soldiers with grenades strapped to them. On one section of the front, 200 of these “living mines” lay down in front of advancing tanks. Suicide attacks only initially had results. Red Army soldiers quickly learned to remain vigilant, and the attacker was usually shot before he could get in range and harm infantry or tanks.

3. Finale

On August 15th, Emperor Hirohito addressed his country by radio, informing the population that Japan accepts the conditions of the Potsdam conference and surrenders. The Emperor called his people to display courage, patience, and unite their strength to build a new future.

Three days later, on August 18th, 1945, at 13:00 local time, a radio message was issued from the Kwantung army general staff to its soldiers, which informed them that the decision to surrender was made, as continued resistance was futile. Over the next few days, forward detachments of the Kwantung army with no radio link were informed by messengers.

Most soldiers accepted surrender without any objections. Furthermore, in the city of Chanchun, where Soviet forces were insufficient, the Japanese themselves guarded military installations. Even so, a small number of fanatical soldiers and officers continued to resist, refusing to accept a “cowardly” order to cease fire. Their war only ended when they died.

On September 2nd, 1945, the act of unconditional surrender of Japan was signed aboard the American battleship Missouri. This date marks the official end of the Second World War.

Original article available here.

T is for Tschechisch

The Wehrmacht was pretty big on using enemy equipment whenever possible, appending it with the first letter of the country of origin. French equipment had the (f) suffix (Französisch), Soviet equipment had (r) (Russisch), etc. Some of the most frequently used captured tanks were Czech, the Pz 35(t) and Pz 38(t) (Tschechisch). However, in tank names, "t" following a number usually indicates mass. Naturally, some people were confused.

One such person was the translator of Franz Halder's diaries, as a result of which, the Russian version has the following line: "Reinforcements for tank units: Tanks will be sent from Germany ( PzIII - 100, 38-ton tanks - 40, PzIV - 40)"

Seeing as how this is August of 1941, and Germany didn't have anything close to a 38 ton tank, this is clearly a Pz 38(t). These mistakes also appear in several other non-German sources. The mistake is even common enough to be made fun of in the "Girls und Panzer" cartoon.

However, it seems it was more common than originally though.

Seeing as how the PzIII was not even close to weighing 35 tons, clearly some confusion with the Pz35(t) is taking place.

KV-4 Armour Thickness

Monsters like the KV-4 were built for a reason. The USSR knew of powerful German AA guns that could be used in anti-tank roles, and wanted to be ready for them.

CAMD RF 38-11355-14

The first column is the caliber of the AA gun, second is the thickness of the armour in question, third is the angle of the armour, fourth and sixth are the quality of the armour for penetration and nonpenetration, respectively. Columns five and seven contain the speed at which the penetration or nonpenetration would occur. The last column indicates the type of the armour: the armour is homogeneous in all cases except 2-5, where it is surface hardened with high frequency current.

The conclusions are as follows: "In order to protect the tank from the 105 mm AP shell at all distances, it is necessary to have 130 mm of armour minimum, with high hardness (2.8-3.2) or surface hardened with high frequency current. Even under these conditions, the armour will be breached when hit at 800 m/s at normal."

Inside the IS Turret

Getting measurements of the outside of a tank is easy, just go to a museum with a tape measure. Getting inside is harder. Thankfully, there are blueprints we can look at!

"Diagram of equipment locations in the fighting compartments of the IS tank and KV tank with IS turret, armed with a D-5 gun"

CAMD RF 38-11355-1529

The gunner sits on the left, the loader sits on the right. The commander sits behind the gunner, underneath the cupola. A radio is positioned right next to him. Ammunition is stored in a case behind the crew, in the rear of the turret. The rectangle in the center is the gun. 

The images on the bottom are views from the side, showing the "KV-D5" (left) and "IS-D5" (right). 

"Diagram of equipment positions in the KV tank with an S-31 gun"

The layout of the KV with an S-31 (Object 238) is similar to that of the IS tank. However, you can see one major difference that proved fatal to the project: the gun is only 75 mm away from the turret ring, unlike the D-5, which enjoys 430 mm of clearance. Because of this, the commander's position must be shifted to the left, leaving no room for his radio. 

Intelligence Gathering

Capturing enemy soldiers is a good source of intelligence on the eve of a battle. However, sometimes the intelligence is not so good.

CAMD RF 38-11355-1712

"A captured unteroffizier of the 226 infantry division Frmake Max said that he overheard other soldiers and officers discussing a new German super-powerful tank called "Panda-S", which, compared to a Tiger, has higher speed, thicker armour, and more powerful armament."

Soviet Intelligence is, as always, skeptical. Notes are made on the file: "Voroshilov: we need to confirm this report" and "we need to obtain through Sidorovich". What needs to be obtained is not written. Presumably the tank in question.

This is likely a misheard interpretation of the Panther. It was faster, had more armour (in the front), and a gun with higher penetration.

CAMD RF 38-11355-939 uncovers more German secrets: "Gefreiter Strembel Helmut reports that the German army has new tanks, that have armour that cannot be penetrated by any AT gun. Air is compressed between two steel walls, drastically increasing effective armour without increasing weight or decreasing speed."

This is, of course, spaced armour. Spaced armour does use air in between armour plates, but it is not compressed.

The following discoveries, on the other hand, are not at all linked to reality.

"To the head of GABTU: Lieutenant-General of the Tank Forces, comrade Fedorenko.

German sources report that the German army knows of a tank in the Red Army that weighs 115 tons.

Acting head of the communications department of the General Staff of the Red Army
Brigadier-Engineer Panfilov

May 5th, 1941"
CAMD RF 38-11355-298

"To the deputy chief of GABTU, Major-General of the Technical Forces, comrade Lebedev

According to obtained documents, the Germans, as a result of interrogating prisoners, are aware of a tank that is allegedly being produced at the Chelyabinsk factory:

Mass: 125 tons
Side armour thickness: 20 mm
Length: 750 cm
Width: 370 cm
Height: 380 cm
Speed: 30-40 kph

The German high command is very interested in obtaining more details on this tank.

Chief of the 1st department of the 2nd directorate
GRU, General Staff of the Red Army
Colonel Hlopov

June 2nd, 1942"
CAMD RF 38-11355-651

"An Azerbaijani from the 68th Tank Brigade ... was at a theoretical tank lecture, where Captain Motovalov told of new Soviet tanks. The tanks had 2, 3, and 5 turrets, and were soon to be included in the Red Army's tank forces. The facts revealed at the lecture were top secret, and were not to be repeated. Captain Motovalov said that the 68th brigade was the most reliable, and will get the new tanks for combat trials. In November/December, the brigade received two new tanks: a two-turret with a rocket battery on the roof and a five-turret.

The man reports that the tanks look like this: the two-turret tank is slightly bigger than a KV, the central turret is oval, and has a 76 mm gun and two machine guns. The top of the turret has 8 rockets, each mounted on a rail. The rocket rails can spin independently of the turret, 360 degrees. There are armour piercing rockets.

The second turret is to the left, has a 78 mm gun, and a coaxial machine gun. The turret can turn 150 degrees. There are two machine guns in the front of the tank, and the tracks are protected with armour. The tank can reach a speed of 45 kph. The tank has a plate with the name of the manufacturer: "Kaganovich factory".
NARA T-78-R579-F0887

I guess the "KV-VI Behemoth" has a historical basis after all!

T-26 Upgrades

The Red Army was very impressed with the Vickers 6-ton, and had very big plans for it. Aside from the plain copy with machine-gun turrets, the following were planned in 1931:

"Enumeration of artillery systems.

1. Artillery support weapons

37 mm AA guns: chassis: T-26, mass: 7-7.5 tons, speed: 30-35 kph, gun range, in degrees: vertical: -5 to +80, horizontal: 360, carries 200 shells. Crew: 3

...

2. Reconnaissance support weapons

...

76 mm SPG (direct support weapon). Chassis: T-26, mass: 6-7 tons, speed: 30-35 kph, armour: 10 mm, gun range, in degrees: vertical -5 to 30, carries 180, transports 40-50 shells. Crew: 3.

3. Infantry support guns.

45 mm anti-tank gun. Chassis: T-26, mass: 6-7 tons, speed: 30-35 kph, armour: 10 mm, gun range, in degrees: vertical -5 to 30, horizontal 360, carries 100 shells. Crew: 3.

122 mm mortar. Chassis: T-26, mass: 7-8 tons, speed: 30-35 kph, gun range, in degrees: vertical 0 to 75, horizontal 60, carries 20-30 shells. Crew: 3.

4. Tank unit guns.

45 mm semi-automatic SPG. Chassis: T-26, mass: 6-7 tons, speed: 50 kph, armour: 10 mm, gun range, in degrees: vertical -5 to 30, horizontal 360, carries 100 shells. Crew: 3. The gun is identical to that used by anti-tank infantry units.

76 mm SPG. Chassis: T-26, mass: 6-7 tons, speed: 30-35 kph, armour: 10 mm, gun range, in degrees: vertical -5 to 30, horizontal 360, carries 100 shells. Crew: 3. The gun is identical to that used by reconnaissance units, but with reduced armour."

In 1933, some more ideas.

"Report on experimental works at OKMO for January

TR-1: APC on the T-26 chassis. "Hercules" 90 hp engine. Project 100% completed, working blueprints 95% completed, copying 90% completed.

TR-4: APR on the T-26 chassis, with a new hull. Project 95% completed, working blueprints. 

Development of the second T-26 series: experimental blueprints completed 100%, replication of blueprints completed 75%.

Two 76 mm gun systems are being explored. The main, which the turret was designed for is the semi-automatic short PS-3 and, temporarily, the short regimental model 1927 cannon with shortened recoil."

World of Tanks History Section: PzKpfw I

On June 28th, 1919, Germany and the Entente signed the Treaty of Versailles, ending WWI, the largest conflict in the history of humanity at that point. A portion of German territory was annexed by the victorious nations, its colonies were also appropriated, it was forced to pay reparations. There were also harsh limits on Germany's military force. The land army was limited to 100 000 men, drafts were not allowed, a portion of Germany's warships were handed over to the victors, and the tonnage of new ones was strictly limited. Armoured vehicles (aside from outdated police cars) and aviation were forbidden. The conditions were such that their goal was, apparently, not to maintain peace in Europe, but to humiliate Germany and force them to take revenge.

Years before the nazis, Germany already started to, step by step, violate the conditions of the treaty. Aside from theoretical developments, which were not forbidden, the manufacturing base of the country slowly but surely accumulated experience. In 1925, a tank codenamed Großtraktor (large tractor) was developed. Leichttraktor (small tractor) followed in May of 1928.

The first mass produced German tank was the PzKpfw I. Work on this tank started in 1931, when the Directorate of German land forces drafted the requirements for a teaching tank, 5 tons in mass. The vehicle was officially named Landwirtschaftlicher Schlepper (agricultural tractor), which was not unusual in Germany at the time. Friedrich Krupp AG, Rheinmetall-Borsig, MAN, and Daimler-Benz AG received orders for this new tank.

Each company produced a prototype with more or less the same characteristics. The military liked Krupp's LKA tank the most. The best thing about it was not its technical characteristics, but that it was the project that could be built the fastest, and the cheapest. Five of Krupp's tanks, still without armament, were tested at Kummersdorf in the summer of 1933. The tests demonstrated insufficient reliability of the transmission and suspension, forcing Krupp's engineers to make some changes. After that, 15 more vehicles were given the green light. The vehicles were assembled at multiple factories. This unorthodox decision was made to distribute the tank building experience.

The hull and turret were developed by Daimler-Benz. A welded hull protected the crew and components from bullets. The turret, also welded, was placed to the right of the tank's axis. The maximum armour thickness was 13 mm. The tank was equipped with a Krupp 57 hp engine, theoretically making it capable of accelerating to 37 kph. The tank's armament consisted of two 7.92 mm MG-13 machine guns.

The first mass produced chassis were made in December of 1933. In July of 1934, the tank started mass production. In the same year, the first tanks started arriving at training centers. By October 1935, Germany's first tank divisions were formed. That is when the tank received its name: PzKpfw I. According to foreign historians, there were about 1100 vehicles of the first configuration built.

When the tank entered the army, its downsides quickly showed themselves. Its engine was too weak. Instead of the ideal 37 kph, it could only reach 28 kph. Work started on an improved PzKpfw I Ausf. B. Retroactively, all existing tanks were named PzKpfw Ausf. A.

In 1935, the new six cylinder water cooled Maybach NL 38 TR engine was chosen for the tank. The new engine was more powerful, at 100 hp. Because it was larger than the engine compartment of the PzKpfw I, the tank became longer by 40 cm. The tank gained another road wheel, and an idler was lifted to make turning easier.

Interestingly enough, no work on improving armament was conducted. First "B" tanks were equipped with the same MG-13s, and later, dual MG-34s. These machine guns fired a little faster, but had the same rifle caliber. If the firepower was improved, it was so miserly, that it is not worth mentioning.

The PzKpfw I Ausf. A remained in production until 1937, and the chassis until 1941. The PzKpfw I was seen as a strictly training tank. However, as it often happens, reality interfered. Until 1937, the PzKpfw I was the main tank of the German army. Germany started WWII with over 1000 PzKpfw I of both modifications.

The tank saw its first combat in Spain, during the Spanish Civil War. Various sources record 32-41 tanks shipped along with the German volunteers of the Condor legion, fighting on the side of Franco. These tanks formed the Drohne tank group. Despite the fact that the group's main function was to teach Spanish tankers, the group frequently saw combat. The very first battles showed the superiority of Soviet T-26 tanks, armed with cannons. Armour piercing bullets could penetrate the T-26 at 120-150 meters, but it was hard to close in to that distance, as the T-26's 45 mm gun could destroy the PzKpfw I at any range.

In order to somehow improve the situation, there was an attempt to install the Breda 20 mm autocannon. In order to fit the gun into the turret, it had to be modified with a cylindrical addition. There is no data on the combat use of this "homebrewed" vehicle.

In 1938, Germany started expanding its territory. PzKpfw I took part in the Anschluss of Austria. Here is where the PzKpfw I showed its poor reliability. At least 35% of both types of tank broke down and were abandoned by the side of the road during the march. In order to conserve the negligible number of tanks, they were delivered to the Sudetenland by trucks.

During the Polish campaign in 1939, most tanks in the German army were still PzKpfw Is. Weak armour and armament were apparent. 320 tanks were lost, but most were repaired by the Germans.

At the time of Germany's advance in the West, only 550 PzKpfw I tanks remained, and they were assigned secondary roles. Even then, the losses were very great, and 182 units were lost irreparably.

As time went on, the amount of PzKpfw I tanks declined. In the West, as well as the East, they were used until 1944, primarily to combat partisans.

Small amounts of PzKpfw Is were shipped to China, Hungary, Spain, and, according to some sources, Croatia.

Original article available here.

Shell Shape

WWII era artillery shells are all look more or less the same to the untrained eye. However, much ink was spilled in the discovery of what shape was best. Documents in CAMD RF 81-12042-85 tell a small part of that story. The document is almost entirely text, so I will not include scans. They can be found here.

"In all nations, without exception, armour piercing shells for anti-tank and field artillery are produced with sharp tips. Our shells (45 mm and 76 mm) are made only with blunt tips. Comparing their effect on tank armour shows an advantage of sharp armour piercing shells over blunt armour piercing shells. 

Blunt tipped shells migrated to land artillery from naval artillery, because a blunt shell penetrates heterogeneous (for example, cemented) armour, hardened on the surface and softer in the back. This armour is commonly used on battleships.

Homogeneous armour, armour with uniform hardness, resists blunt shells much better than sharp shells. On tanks of all countries, including Germany, armour is homogeneous, which means that using sharp tipped shells will be more effective than blunt tipped shells. Sharp tipped shells also have an advantage when fired at an angle, which happens most often. A blunt nosed shell that hits armour at an angle ricochets. A sharp nosed shell, when hitting the armour, bites into it, and penetrates. The comparative effects of sharp and blunt 45 mm armour piercing shells are shown on the table below."

The performance of the sharp tipped shell is the upper row. The performance of the blunt tipped shell is the bottom row. The table shows distances at which the shells penetrate, in meters, at the specified angle. The blunt nosed shell performs more poorly against 40 mm of homogeneous armour every time, and does not penetrate at all when the armour is sloped 45 degrees.

"Trials showed that sharp-tipped 37 mm shells work better than blunt tipped 45 mm shells, at higher muzzle velocities.

There are two reasons why we do not need to worry about the armour piercing properties of our shells. One is that our 45 and 76 mm guns are very powerful. The other is that German tanks are weakly armoured (40-50 mm in the front, 30 mm on the sides), and German armour is of poor quality.

These two factors somewhat mitigate the deficiency of blunt nosed shells.

Experience shows that the Germans keep increasing the thickness of their armour (in part, the front section of all German tanks has additional screens), and the mass of German heavy (PzIV) and medium (PzIII) tanks keeps growing. We must be ready to penetrate thicker armoured German tanks. This can be accomplished by means of using sharp-tipped shells. The penetration of sharp tipped shells may also be increased by using any of well known methods (variable hardening, cementing, welding on a cap, etc). 

I think that it is imperative to immediately begin production of sharp-tipped armour piercing shells for anti-tank artillery.

June 27th, 1942

V. Malyshev"

Malyshev was right, German tanks kept getting more and more armour. However, GAU KA responded to his letter a few days later:

"The influence of tip shape on penetration was studied at GAU KA as soon as armour piercing shells were introduced to land artillery. 

In 1935-36, ANIOP, under orders from the GAU KA, performed a study on this topic (NIR #25, 1936), which led to the following conclusions:

"All armour piercing shells must be produced with a blunted part about 0.7 calibers long, as shells with this blunting need less speed to penetrate an armour plate than shells with a sharp tip under most conditions." (part 8 in NIR-25, 1936).

Further along, as armour quality improved, and as necessity to produce improved armour piercing shells increased, trial shells frequently were developed in two variants: sharp tipped and blunt tipped, and were tested on homogeneous and heterogeneous armour plates.

During the last pre-war years (1939-1941), development and testing of improved armour piercing shells was performed with cemented armour, over 30 mm thick, with resistance coefficient K=2500-2700. The reason for this was that the Izhor factory sent GAU KA the sturdiest armour plates, the cemented ones. Additionally, the so called "destructiveness" of the tip of the shell was higher for cemented plates than homogeneous ones. As such, tests against cemented armour were considered more rigorous when it came to examining shell quality. New types of shells were usually also tested against homogeneous armour.

We did not have precise information on armour plates of our enemies, so GAU KA had to make sure its engineers produced shells that are effective against both homogeneous and cemented armour, as ordering shells that work only against cemented or only against homogeneous armour would have been incorrect.

The main characteristics of a shell hull are the following: speed of penetration, hull sturdiness, and lack of ricochet.

NII-48 trials (see report #1757ss dated November 19th, 1940), ANIOP trials (see report #0264ss-40), and trials of the Main NKSP Directorate demonstrated that sharp tipped shells work better against homogeneous armour at 0 degrees, and require less speed than blunt tipped shells, but work worse against cemented armour.

When shooting at a plate at an angle away from normal, as the angle increases, performance of the sharp tipped shell decreases compared to the blunt tipped shell, against both cemented and homogeneous plates. 

1. The blunt nosed shell can survive an impact against armour better.  Usually, the sharp tipped shell penetrates the armour 30-40 mm away from the place of impact at a 30-45 degree angle, which means the chance of ricochet is higher.
2. The rigidity of the sharp shell is worse when shooting at an angle, compared to a blunt shell.

The above examples of theoretical and experimental works fully back the decision to adopt blunt-tipped shells. Study of captured armour piercing shells and their comparative trials showed that:

1. All captured shells without caps are sharp tipped. If there is a cap, the tip is dulled.
2. The front part of the shell is very hard (up to 62-65 Rc), which is achieved by:
1. use of instrumental steels
2. welded on tip
3. very fine grinding, and even polishing, of the shell tip

Domestic armour piercing shells are made from more ductile 35 HGS grade steel, and, according to work of NII-24, are not improved by the above methods.

Sharp tipped armour piercing shells are only superior when manufactured from instrumental steel. At this time, the transition to instrumental steel, requiring special thermal treatment for the required high hardness and polishing of the shell tip or a welded on shell tip, would be difficult, and production of large amounts of these shells is not possible.

In order to evaluate the penetration of sharp-tipped armour piercing shells made from instrumental steel using our calibers, GAU KA gave an order to produce these shells at the beginning of 1941, but they were still not manufactured."