F-34 Installation

"Technical Meeting Minutes

Held on September 8th, 1940, at the State Order of Lenin Comintern Factory #183

Present:

• Factory #183 Chief Engineer, Makhonin
• Factory #183 Deputy Chief Designer, A.A. Morozov
• Factory #92 Senior Engineer-Designer, P.F. Muravyev
• Factory #92 Technician-Designer, B.G. Lasman
• Factory #183 Senior Engineer, Maloshtanov
• ABTU Military Representative, Military Engineer 3rd Class, Baikov

Topic: comrade P.F. Muravyev's presentation regarding the possibility of installing the 76.2 mm F-34 tank gun in the T-34 turret and the conversion of the T-34 turret made necessary by the requirement that the F-32 and F-34 be made interchangeable.

F-32 in A-34

"Secret

To the ABTU Chief, Corps Commander Pavlov

NKO House, 2 Red Square, Moscow

On the issue of: production of armour and assembly of A-34 hull and turret.

The armour for the A-34 is ready, both for the hull and the turret. The hull is in the finishing stages of assembly, the turret assembly will begin on December 22nd.

F-32 Technical Passport

Despite the stereotypes of poor Russian organization, major components of a tank (the gun, the radio, the engine, etc) all came with a technical passport that contained the data for the item in general and this specific item in particular. Here is a technical passport for a F-32 gun installed in a KV tank.

Unique T-34 Turret

Iam-Krasnoyarsk found an interesting picture.

At first sight, it's a simple model 1942 T-34 turret used as a bunker. However, looking at the barrel length, it's far too short. This isn't a simple T-34, it's using the F-32 gun from early KV-1 tanks! However, the F-32 gun that was meant for a heavy tank didn't fit into a medium tank's smaller turret that easily. It's clear that whoever made this emplacement had to do some work adjusting the turret "cheeks". Instead of being the common quarter-spherical shape, the side is now a 90 degree angle, forming a cylinder. 

Artillery Wishlist for 1940

The Supreme Military Council made a recommendation in May of 1940 regarding the state of artillery in the Red Army. The first half is about AA guns, and falls outside of the scope of this blog, but about halfway through, we get some juicy tidbits.

"
4. Consider large caliber artillery a task of utmost importance. Develop 210 mm field guns, 305 mm field howitzers in 1941, and 356 mm guns and 500 mm howitzers on rails for 1942. Develop and build prototypes of a 450 mm field howitzer in 1941.

5. On anti-tank guns:
Organize the manufacture of 45 mm shrapnel shells, producing 200,000 of them in 1940. GAU should develop an anti-tank gun, 50-60 mm in caliber, that can penetrate 50 mm of armour at 1000 meters.

Regimental guns:
Regimental guns currently being developed do not match the requirements of regimental guns due to being too heavy (900 kg). Currently developed guns should be completed and tested. In 1941, develop a new regimental gun, that weighs no more than 500 kg, has a 5 km range, and is not made for fighting tanks.
...
Medium caliber tank gun:
Leave the L-11 tank gun for 1940 Gradually shift to the F-32 and develop a new, more powerful tank gun  that is capable of fighting modern tanks. Hold the development of the F-32 until this issue is resolved.

6. On the armour piercing capabilities of field artillery.

Develop AP shells for the following artillery systems:

• 152 mm model 1938 howitzer
• 107 mm model 1910/30 gun
• 122 mm model 1931 gun
• 152 mm model 1935 gun
• 152 mm model 1937 gun"

As always, let's see how successful these requests were. The massive artillery isn't really my department (I included it for fans of large numbers), but it looks like they got somewhere, combining the 450 mm requirement and the rail requirement into...something.

CAMD RF 81-12104-36

The request for a 50-60 mm AT gun was met with the 57 mm ZiS-2. According to the table here, it overfulfilled the penetration requirement, with 75 mm of penetration (against armour at 30 degrees, no less) at 1000 meters. Similar results are achieved by the ZiS-4 here.

The request for a lighter regimental gun was almost satisfied with the model 1943 regimental gun. At 600 kg of combat weight, and with a 4200 meter range, it doesn't quite get there. Also, unlike in the requirement, it was issued with HEAT shells, making it capable at fighting enemy tanks at under 1000 meters.

The development of AP shells for the listed artillery systems was very much successful, and is explored in another article.

A GABTU wishlist for 1940 (CAMD RF 38-11355-10)  also has some artillery components in it:

"On artillery:

1. Immediately mass produce the 107 mm M-60 gun.
2. Order the 107 mm mountain gun.
3. Accelerate the trials of 203 mm howitzers.
4. Accelerate the trials of AP shells for 107 mm, 122 mm, and 152 mm guns.
5. Select the best possible 76 mm AP shell, and equip 76 mm model 1933 AA guns with it.
6. Develop armour piercing shells for the 122 mm model 1938 howitzer, 152 mm model 1937 gun-howitzer, and 152 mm model 1938 howitzer.
7. Develop armour piercing shells for 37 mm, 45 mm, and 85 mm AA guns."

GABTU's Tank Wishlist for 1940

The Red Army received a new heavy tank in 1940, and GABTU wasted no time before demanding more things from it. CAMD RF 38-11355-10 tells us the full story.

"

1. The KV tank must have a 76 mm gun with a muzzle velocity of at least 800 m/s, in order to penetrate 70-80 mm of armour at 1000 meters. The gun must fire quickly, and have sufficient stock of ammunition. Must have an armour piercing shell and a high explosive grenade.
   At this time, the most appropriate gun is the AA gun model 1931. The tank should also have 90-100 mm of armour.
2. The KV-2 tank must have a 107 mm gun with a muzzle velocity of 730-750 m/s in order to penetrate 100-110 mm of armour at 1000 meters. The gun must fire quickly, have high penetration, and have sufficient stock of ammunition. Must have an armour piercing shell and a high explosive grenade.
   At the time, the most appropriate gun is the 107 mm M-60 gun.
3. Build heavy self propelled armoured artillery to destroy pillboxes. Use a 122, 130, 152, and 180 mm guns. 
1. The most realistic way of solving this problem is the production of an SPG on the SMK or T-100 chassis, and installing a 100-130 mm gun on it, giving it an AP shell capable of penetrating 130-150 mm, and an HE shell. 
2. In short order, develop an experimental 152 mm model 1935 gun (Br-2) mount on the SMK tank, supply the system with an AP shell capable of penetrating 150-160 mm of armour, and a concrete wall 1.5 meters thick.
   The gun must be protected by 60-70 mm of armour and weigh no more than 65 tons.
3. Install a 180 mm gun on the SMK chassis. If necessary, alter the chassis, and reduce armour. [This entire paragraph is scratched out]
4. During the transitional period:
1. Manufacture KV tanks with a 152 mm model 1938 howitzer (M-10).
2. Manufacture KV tanks with L-11 guns and regular shells.
3. Immediately develop a mount for the 76 mm AA gun model 1931 and the M-60 107 mm gun.
4. Immediately begin producing the T-100 with a 130 mm gun, and begin work on installing a 152 mm model 1935 (Br-2) gun on the SMK.
5. Install 122, 130, and 152 mm guns on the T-35 and simultaneously test armour screens.
6. Have two types of T-34 tanks, ones with 45 mm guns, and ones with 76 mm guns. Improve the armour piercing capability of the 45 mm gun, and use F-32 or F-34 guns.
7. All tanks must use DS machineguns with thickened barrels, as they allow for longer continuous fire than the DT."

That's a lot of requirements. Let's go through and see which ones came true.

The first one came from the L-11's already insufficient AP performance. The F-32 gun that the KV-1 was stuck with had the same ballistic properties. The KV-1 didn't get a gun that satisfied this requirement until the ZiS-5. Next, the KV-2's 107. The tank was tested with a gun of that caliber, and it met the penetration requirements, but the KV-2 had no worthy opponents in 1941, and production ceased. 

Heavy self propelled guns are a whole different topic. The SU-100-Y definitely satisfied the 130 mm bunker buster requirement. The requirement for a mobile 152 mm gun wasn't met until the SU-152. The Br-2 was mounted on several self-propelled platforms, but never mass produced in that configuration. Its half-AP shell could penetrate 180 mm of armour, so that requirement is satisfied. 

The KV with an M-10 was certainly manufactured (KV-2). The KV-1 eventually switched to the F-32, and then ZiS-5 guns. The model 1931 AA gun was only ever tested in the T-34, and then discarded, as it was not necessary with the advent of the T-34-85. The T-100 with a 130 mm gun was the SU-100-Y, so that one was successful. The T-35 with a 152 mm gun wish was granted, in the shape of the SU-14, but only two were built.  

Plans were drafted to built T-34s with 45 mm guns in the event of a shortage of 76 mm guns, but such a shortage never happened. The T-34 received the F-34 in 1941. The AP capability of 45 mm guns was improved, with the 45 mm AT gun model 1942.

A number of these requirements was drafted with the Winter War in mind, when the Red Army was stuck on Finnish defensive lines. When Germany invaded, the USSR no longer had any use for bunker busters, as the bunkers they would have to one day storm were hundreds of kilometers away. Additionally, Germany did not bring any tanks with armour as thick as was foreseen, so 107 mm guns with ridiculous penetration were not needed.

ZiS-5

"In order to solve the issue of arming the KV-1 tank manufactured by the Chelyabinsk Tractor Factory, the workers of factory #92, factory director comrade Elyan, chief engineer comrade Grabin, and chief of the OGK sub-department comrade Muravyev, determined the following:

1. In August of this year, factory #92, while mounting the F-34 gun on the KV-1, reinforced the gun mount as a result of having to move the trunnions in order to balance the gun (which takes as much effort as making a new mount).
2. The resulting 76.2 mm caliber gun is called "ZiS-5" by the factory, and is preferable for installation in the KV-1 tank for the following reasons:
1. The mount is sturdier, with 15 mm walls instead of 8 mm.
2. The button firing mechanism is made according to the Artkom GAU KA journals, and is superior in performance. 
3. A T-900 4x sight is used instead of a 2.5x sight, in order to reduce the opening in the gun mantlet.
4. The muzzle velocity of the armour piercing shell can be increased to 780 m/s with a special charge, which increases penetration to 75 mm at 1000 meters.
3. Factory #92 received an order from Moscow to cease manufacturing of prototypes, despite the fact that parts for 25 prototypes have already been produced.
4. Since the Kirov factory has stopped supplying ChTZ with F-32 guns as of August this year, ChTZ was ordered to install the F-34 gun on the KV-1, with all required mount trunnion changes. In order to assist in this, one engineer from factory #92 was sent to ChTZ by airplane with one F-34 gun, and later, 16 more F-34 guns were sent by rail. If necessary, factory #92 can send more of its employees.

Conclusions:

1. It will take as much time to adapt the F-34 gun to the KV-1 as it would take to produce the ZiS-5 gun.
2. No additional equipment is required to produce the ZiS-5 gun. Required tools have already been ordered by the factory. The factory has necessary blueprints and instruments.
3. Factory #92 can start manufacturing ZiS-5 guns at the cost of removing other guns from production, such as the F-34.
4. Major-General comrade Grabin made it clear that he can produce 20-25 ZiS-5 guns in excess of the factory's quota.
5. Major-General comrade Grabin stated that all he saw on the issue of producing the ZiS-5 is talk, and despite its advantages, there is no singular decision. If this continues, he will have to write to Stalin personally.

September 27th, 1941"

CAMD RF 38-11355-148

Letters to Stalin or not, but the ZiS-5 gun made it into mass production for the KV-1. The special AP shell, on the other hand, didn't, as every source that I have read gives identical ballistics for the F-34 and ZiS-5. 

Penetration, Part 2

I have already written an article on a very wide-spread penetration table. Here is a table for some lesser-known guns (regrettably, missing most of the ones I was interested in).

CAMD RF 38-11353-950

This document shows the penetrations of some pre-war guns, and their caliber, muzzle velocity, and shell weight. This table lists some guns we're seen before (ZiS-4, 45 mm tank gun, F-34), but some new ones. There is the DShK, whose practical penetration I covered here. The table gives it 25 mm at 0 degrees and 200 meters, and 10 mm at 30 degrees at the same distance. This seems pretty fair when compared to those tests.

Another interesting gun is the F-30. It was tested in the T-28, and never made it into anything in mass production. 100 mm at 1000 meters at 0 degrees and 90 mm at 30 degrees is around the same as the D-5-T. A lot of the time, different guns that use the same shell do not actually possess different ballistic properties, but are instead differentiated by cost, size, ease of use, etc.

We see another gun I covered next, the ZiS-6. The penetration against a 30 degree sloped plate is the same as in that document, but this document shows the penetration against a flat plate at that distance: 128 mm.

The gun after that is the M-10 on the KV-2. I can't imagine that it was used very frequently with AP, given how devastating its HE shell was. There is at least one case of KV-2s using concrete-piercing shells against tanks. This gun achieves 85 mm against a sloped plate at 1000 meters, and 90 against an unsloped plate. This is worse than the ML-20 152 mm gun in the other penetration table, which is expected, given the M-10's shorter barrel length.

CAMD RF 38-11353-951

Now we get into something really interesting: foreign guns. Since there was not yet a chance to discover the penetration of German guns firsthand, these are based on data from military intelligence. Let's take a look. Keep in mind that a) this data is from gathered intelligence and is bound to be approximate, especially considering that b) the Germans tested to a 50% penetration standard, and the Soviets to a 75% penetration standard.

The first entry is "Rheinmetall Borsig" 37 mm. The shell mass is reported as 0.665 kg, at 800 m/s. This penetrates 40 mm at 250 meters and 26 mm sloped at 30 degrees at 600 meters. The Germans' own data shows the 3.7 cm PaK 36 as having 31 mm sloped at 30 degrees of penetration at 500 meters. Projectile weight and muzzle velocity are pretty close too. 

The next gun is "Rheinmetall Borsig" 47 mm. I have no idea what this is supposed to be, but it doesn't penetrate very well, and this is at very close distances.

Next is an 88 mm AA gun. Apparently it shoots a 9 kg shell at 820 m/s, which is a little too light and a little too fast, but the penetration numbers given seem consistent with that other penetration table data. 

The next gun is a new one, "heavy gun", 105 mm, maybe a 10.5 cm FlaK gun. The one after is an "anti tank (and also AA) gun, exactly matching a 5.0 cm PaK 38.

After that, we see something interesting: a 66 mm light AT gun, penetrating 75 mm of armour at 800 meters, or 75 mm of sloped armour at 200 meters, firing a 4.5 kg shell at 850 meters per second. Perhaps this is data from some kind of 75 mm squeezebore gun. Or maybe a captured Czech gun? 

The last entry in the table is an 88 mm AT gun, which, for some reason  fires a different shell at a different velocity than the 88 mm AA gun, and also penetrates the same amount of armour at 100 meters, angled or not.