Monday, 24 June 2013

Soviet 45 mm AT Guns

Out of all the Soviet guns produced in the war, the "sorokopyatka" (forty-fiver) was not the biggest or strongest, but it retains a special place in history. The Soviet Union produced numerous guns that were 45 mm in caliber, and they proceeded to fight through the entire war. Each different gun was improved, and had a different name, but they were all known colloquially as "sorokopyatka".

The first such gun was the 45 mm anti-tank gun model 1932 (19-K). Using components from the license-built Rheinmetall-Borsig 37 mm gun and a new 45 mm barrel, a new anti-tank gun was born. It was installed in tanks under the name 45 mm tank gun model 1932 (20-K). Various modernizations of this gun, including a prototype to make it magazine-fed, continued until 1937.

Towards the end of 1937, model 1932 was pushed out by the 45 mm anti-tank gun model 1937 (index 53-K). The new gun had better ballistics, a higher rate of fire, and was more reliable. The new wheels were also made of metal, and not wood (model 1932 also received metallic wheels in 1937).

The tank guns also underwent modernization. The 45 mm tank gun model 1938 had some new features compared to its towed sibling, the most interesting of which was a TOS stabilized gun sight, allowing for accurate fire while the tank was in motion.

The USSR met WWII with a large number of 45 mm model 1937 guns. While they were more than enough against the front of obsolete light tanks, front armour of newer models gave them trouble. APCR shells solved that problem somewhat, but tungsten was expensive, and the gun was further modernized in 1942 into the 45 mm gun model 1942 (M-42). As well as a longer barrel, the gun received a thicker shield, in order to protect the crew from armour-piercing bullets. The USSR stopped producing the gun in 1945, but it was used in Finland as an AT gun until 1966, and only completely removed from service in 1986.

The 45 mm gun had a number of shells developed for it. The high explosive shell generated 100 fragments, with a radius of effect of 10 meters. The penetration capabilities of the AP-tracer shell will be explored further in the article. There was also an AP-tracer-incendiary shell, which ignited gasoline with 100% chance, kerosene with 80% chance, and diesel with 60% chance. Lastly, there was a grape-shot round that spread 150 bullets in a 9 degree cone.

Now, for some tests! Let's dust off the good old  "Report on the shooting of German tanks with AP and HE shells from tank guns" (CAMD RF 38-11355-832). I will also throw in tactical diagrams developed by NII-48 in their report: "Topic 2VV-2, Investigation of the armour of tanks of the German army" (CAMD RF 38-11355-778). The report contains the following data for shooting at the armour plates at various angles, which was used to make the tactical diagrams.

  • 30 mm: 
    • 0 degrees: 20% chance at 1600 meters, 80% chance at 1400 meters.
    • 25 degrees: 20% chance at 1100 meters, 80% chance at 1000 meters.
    • 35 degrees: 20% chance at 1000 meters, 80% chance at 900 meters.
    • 45 degrees: 20% chance at 500 meters, 80% chance at 250 meters.
    • 55 degrees and above: 20% chance at 50 meters.
  • 40 mm
    • 30 degrees: 20% chance at 600 meters, 80% chance at 50 meters.
  • 20+20 mm
    • 0 degrees: 20% chance at 650 meters, 80% chance at 150 meters.

First, we have the Pz 38(t), facing off against a 45 mm gun model 1934 (slightly modernized model 1932).

100 meters, a shot to the 50 mm front. The shell penetrates. Entrance diameter: 49 mm. Exit diameter: 55 mm.
200 meters. One shot penetrates. One shot does not, leaving a 20 mm deep dent in the second armour plate. A third shot penetrates again.
400 meters. The first armour plate is penetrated, but not the second.
800 meters. Insignificant damage to the first armour plate. Aiming a bit higher, at the turret armour underneath the gun, the shell penetrates. The turret ring is destroyed.
At 1000 meters, the gun penetrates the side of the turret. At 800 meters, it penetrates again, making a hole 80 mm wide at the entrance, 100 mm wide at the exit, as well as three 300 mm long cracks, and a dent on the other side of the turret, with spalling on the other side.
Another shot from 800 meters ricochets. The next makes a hole in the side of the hull. Entrance diameter: 100 mm. Exit diameter: 150 mm.
A parting shot from 1000 meters penetrates the right side of the hull.

Conclusions: "The 45 mm AP-T shell penetrates the front armour, 50 mm thick, from 200 meters. Side armour, 30 mm thick, can be penetrated by the AP-T shell from 1000 meters."

The NII-48 report calculates more precise figures for the distances. The side of the turret platform can be penetrated at 1070 meters. The side of the turret can be penetrated at 970 meters.

Tactical diagram of a Pz 38(t). The 45 mm gun is shown on the left side.

The next victim of the 45 mm gun is the StuG. The gun is now a model 1942.

Two shots at the front, from 50 meters and 100 meters. Both fail to penetrate, making 20 millimeter dents. The side of the hull is penetrated twice from 850 meters.

Conclusion: "The 45 mm AP shell fired from a model 1942 AT gun cannot penetrate the front armour at any distance. The side armour, 30 mm thick, can be penetrated from 850 meters."

By NII-48's calculations indicate that a 45 mm gun can penetrate the side of a StuG from 1070 meters, and rear at 750 meters.

Tactical diagram of a StuG III. The 45 mm gun is shown on the left side.

Next up is the model 1934 again, against a PzIII. Two shots from 50 meters tear off the first 30 mm screen from the front of the tank.
The next shot hits the right turret hatch, from the right. The shell penetrates the turret, tearing off the hatch, and making a 200 mm crack in the turret. A shot at the rear of the turret from 800 meters penetrates. A shot from 900 meters at the front of the turret penetrates, and jams the turret. Shooting at another hatch from 900 meters tears off 6 bolts, 4 of which fly inside the tank. Two shots at the right side of the hull from 900 meters make penetrations (one as big as 75 mm entrance and 120 mm exit), and make a crack in the turret platform. A ricochet from 900 meters makes a 200 mm crack in the right turret side. Another shot to the right side results in a penetration, as well as an 80 mm crack. A parting shot to the right results in a penetration with an 80 mm exit diameter and spalling.

Conclusions: "The 45 mm shell does not penetrate 60 mm of front armour at any distance. It can penetrate the 30 mm turret armour from 800 meters. The side armour, 30 mm thick, can be penetrated from 900-1000 meters."

NII-48 calculations: The lower front plate can be penetrated at 200 meters. The side can be penetrated at 1070 meters. The side of the turret can be penetrated at 640 meters. The rear of the turret can be penetrated at 860 meters.

Tactical diagram of a PzIII. The 45 mm gun is shown on the left side.

Pretty good result, persistent hits to the front result in the tank being knocked out at up to 800 meters! Better than NII-48's calculations, since the shells can penetrate armour that was theoretically impenetrable. Let's take a look at what can be done against a PzIV with the same model 1934 gun.

At 50 meters, the armour is penetrated. At 100 meters, three shots only make dents, and result in cracks on the rear side.
40 mm side armour is penetrated from 400 meters. The next shot "cut a 200 mm long path through the 20 mm horizontal plate of the turret platform, and penetrated the right side of the turret".
At 600 meters, the 45 mm gun can only penetrate the first 20 mm armour screen, but not the second. However, after 5 shots, the screen falls off, as well as an idler. From 800 meters, the results are the same: penetration of the first screen only. HE from 200 meters is ineffective.

Conclusions: "The 45 mm AP shell, when fired from a model 1934 AT gun, penetrates the 50 mm thick front armour at 50 meters. Side armour is penetrated at 400 meters. Un-screened sides of the engine compartment, rear, and turret, can be penetrated at any effective combat distance."

NII-48's calculations are a bit pessimistic: "The front parts of the tank cannot be penetrated by 45 mm shells." The distance given for the screened sides is 310 meters, side of the turret platform is penetrable from 1070 meters, rear of the hull from 940 meters. The calculations agree: non-screened portions of the tank can be penetrated at any distance and angle.

Tactical diagram of a PzIV. The 45 mm gun is shown on the left side.

"Investigation of the armour of tanks of the German army" also has test data for tanks not in the previous report.

The Pz II Ausf B hull can be penetrated in the front from 580 meters, or 680 meters when shooting at the turret or turret platform. The rear can be penetrated from 1070 meters. Other parts can be penetrated from any distance.

Tactical diagram of a PzII Ausf B. The 45 mm gun is shown as a continuous line.

Surprisingly, the 45 mm gun was also tested...against the T-34.

Tactical diagram of a T-34.

This diagram shows "possible penetration" (20% chance). Even then, the 45 mm gun can penetrate the overtrack hull at 100 meters, and side from 300 meters. This is a much better result than any of the tanks listed above.



7 comments:

  1. "The next victim of the 45 mm gun is the StuG. The gun is now a model 1942.

    Two shots at the front, from 50 meters and 100 meters. Both fail to penetrate, making 20 meter dents."

    Correction 20 millimeter dents otherwise the stug would have been turned inside out.
    Hilarious mental image though

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  2. you have listed 45mm as on the right in the first diagram but the image shows it to be on the left. other than that, this is great! thanks

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  3. Conclusions: "The 45 mm AP shell, when fired from a model 1934 AT gun, penetrates the 50 mm thick front armour at 50 meters. Side armour is penetrated at 400 meters. Un-screened sides of the engine compartment, rear, and turret, can be penetrated at any effective combat distance."

    NII-48's calculations are a bit pessimistic: "The front parts of the tank cannot be penetrated by 45 mm shells." The distance given for the screened sides is 310 meters, side of the turret platform is penetrable from 1070 meters, rear of the hull from 940 meters. The calculations agree: non-screened portions of the tank can be penetrated at any distance and angle.
    Thats not a very good perfonmance since it has to be under 100 meters to pierce the front of the panzer 4 of 50 mm, this gun woul be even more inefective against the upgraged panzer 4 with 80 mm armour and dont fool yourself the germans soon changed the panzer 3 with 30+30 mm with the panzer 3 armoured with a single piece of 50 mm armour which made it invulnerable at ranges of 100 meters, since the standar combat range is of 500 meters this gun doesnt look impresive, if you want to kill a german tank use a 76 mm zis 3

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  4. Is there any information and/or pictures available of the 45mm M1932 Mountain gun, developed in the Central Asian Military District? In a report from Western Front's Operations Department on the loss of Volokolamsk dated 30 October, 1941, the strength of the regiments of 316th Rifle Division are listed:
    1077th Rifle Regiment - 2000 men, 2 120mm mortars, 4 76mm mountain guns, 4 82mm mortars, 6 45mm mountain guns
    1075th Rifle Regiment - 700 men, 1 120mm mortar, 2 45mm mountain guns, 2 82mm mortars
    1073rd Rifle Regiment - 800 men, 1 120mm mortar, 2 76mm guns, 4 45mm mountain guns

    The exact model of the 45mm guns is not mentioned, but presumably they are the M1932 mountain AT guns, I believe designed for light weight and capable of breaking down for carriage by pack horse. The 316th RD was formed as an "extra" division - when the CAMD was ordered to raise six rifle divisions, the Central Committee of the Kazakh SSR decided to raise an additional division. This meant it was made up of older reservists, and its equipment was drawn from what was available in the district. Regular M1937 AT guns were in tight supply in 1941. The July shtat for a rifle division had a 6-gun AT battery with each regiment, but no divisional AT battalion. The division was not a mountain division, but was equipped with some mountain guns apparently, presumably because there was nothing better available. If you have any information (I'm writing a book about the defense of Moscow in October) I would appreciate it. I can be reached at radey.zhukov.jack@gmail.com

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    Replies
    1. I'm not aware of a 45 mm mountain gun. There are mentions of 45 mm guns in the records of the 1073rd regiment, but they make no suggestion that these guns are in some way special.

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