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The Last 76 mm Hole Punch

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Armament and vehicles become obsolete quickly in war. This is caused by rapid development of both new types of weapons and defenses. This can be seen in the history of WW2. It's easy to see progress if you compare what the belligerents were using at the start of the war and what they were using in 1945. This applied to all aspects of the tanks: chassis, engines, observation devices, armour, and of course the armament. Tank armament evolved rapidly during the war. This evolution was directly linked to the growth of armour protection. Early war tanks could be defeated with a heavy machine gun, but towards the end gunners had to crack open mobile pillboxes with 150-200 mm of armour. This required rapid development of anti-tank guns.

 
76 mm ZIS-5 gun with ballistics of the F-22, summer of 1941. The gun went into production with USV (F-34) ballistics.

The typical Soviet tank gun at the start of WW2 had a caliber of 45 mm. By 1939 it was clear that a higher caliber tank gun was needed. The 76 mm L-11 was this gun, although it was quickly replaced with the F-32 and then the F-34. However, in June of 1940 orders were given to develop a 76 mm tank gun with ballistics of the 3-K AA gun. This system was named F-27. It was built and tested, but a series of transformations followed. The gun was renamed to ZIS-5 in the spring of 1941, after which the project died for the first time. 76 mm and even 85 mm was no longer enough for a heavy tank, a 107 mm gun was now required. The 3-K was also being phased out in favour of the 85 mm 52-K. The military also didn't want to stock two different kinds of 76 mm shells. Nevertheless, the ZIS-5 lived on, but with the ballistics of the F-22 divisional gun. This gun was tested and even accepted into service, but when the ZIS-5 was put into production in September of 1941, it was built with F-34 barrels. It seemed that this was the end, but the gun came back one last time.

Penetration ability of the 76 mm 3-K AA gun. However, these trials were not carried out entirely correctly, and so did not show the real ability of the gun.

Writers today have the benefit of hindsight. It's easy to say that the military was stupid and couldn't put a gun into the T-34 to defeat the Tiger. However, if one digs deeper, it can be seen that the military was anything but. Work on an 85 mm gun with ballistics of the 52-K AA gun began long before a Tiger tank was tested. Only three months passed before the official start of work on the D-5T and the start of SU-85 and KV-85 production, which is a very short time. This gun was too big for the T-34, which is why the first medium tank to get this gun was the T-43 with a 1600 mm turret ring. There was also another gun that was a halfway point between the F-34 and D-5T (and later the S-53). This was the S-54 gun, a 76 mm gun with ballistics of the 3-K AA gun, a sort of reincarnation of the F-27 and ZIS-5. Let us talk about this forgotten weapon.

Document dated September 16th ordering the development of S-53 and S-54 guns.

The development of T-34 armament followed a logical path. Penetration trials of a Tiger tank showed that the most suitable medium caliber gun for defeating the Tiger tank that could be installed in a T-34 was the ZIS-2. It could penetrate the tank's side from up to 1000 meters. Logically, work to revive the ZIS-4 (tank variant of the ZIS-2) began immediately. There was another medium caliber gun used to shoot at the Tiger, the 76 mm 3-K. In theory, it showed worse results than the ZIS-2, but there are a few caveats. First, the gun issued for tests was very worn out. Second, a number of hits were scored at 60 degrees rather than 90 degrees, which of course reflected on the penetration. There are a lot of questions that need to be asked about the April penetration trials, since the testers failed to hit the tank at all with some guns.

The S-54 was based on the F-34.

Work on the ZIS-4 progressed rapidly. Like the 85 mm gun, work officially began in April of 1943, before the Tiger was shot up. Four T-34 tanks with the new gun were ready for trials in July of 1943, but then the Battle of Kursk gave a lot of food for thought. The decision to cease production of T-34 tanks with 57 mm guns was made around this time. Many attempts were made to put the 154 barrels that were produced to good use. One thing can be said for sure: the Central Artillery Design Bureau (TsAKB) was working on a new gun by September of 1943.

This lineage allowed the gun to easily be installed in a T-34 tank.

This was not a grassroots initiative, orders came from the top. The reasoning for them was sound. The 3-K had the same penetration as the ZIS-4, but a more powerful HE shell. One can't forget that a tank is designed for a wide range of tasks other than shooting at other tanks. The NKV and GAU were looking at the D-5T gun and even angling for a modernization, but as stated above it was too big for the T-34's turret. A 76 mm gun with 3-K ballistics seemed like the optimal choice.

Gun cradle.

The 76 mm gun with 3-K AA gun ballistics was indexed S-54. Interestingly enough, work began around the same time as the work on the 85 mm S-53 gun. It seems pointless to start working on a weaker gun, but the issue was not so simple. The S-53 was essentially just a barrel with 3-K ballistics installed in the F-34's cradle. 85% of the parts were the same, whereas the S-53 was a completely new weapon. The S-54 was more interesting in the short term. It did not require a new turret or significant changes to the gun mount. For some reason no one was concerned about getting ammunition for the 3-K anymore. The decision to drop the ZIS-5 in its initial form was now clearly a mistake, but it was too late. More than two years of progress were lost, but one can't rely on hindsight again. The situation in May of 1941 was different and no one expected that the T-34's firepower would have to be boosted urgently two years later.

T-34 tank with an S-54 gun, November 1943.

The experimental T-34 tank with an S-54 gun was not only built, but also tested at the factory by November 1st, 1943. The gun fired 387 shots and the tank drove for 280 km. Meanwhile, the ZIS-4 was faring poorly and the gun needed more work. Factory #92 lost their chance to put their gun into mass production. As for the S-54, trials began at the Gorohovets ANIOP on November 14th and ended on November 19th, 1943. Since the 3-K used different ammunition, the T-34's ammunition racks had to be altered. Ammunition capacity was decreased to 68 rounds. 7 were stored in the turret bustle, 9 in slots on the sides, and the rest in bins under the fighting compartment floor.

Trials showed that the gun had quite satisfactory penetration.

610 shots were made at these trials, including 324 supercharged rounds. The S-54 was also given subcaliber ammunition. The results were quite different than when the Tiger was tested. The AP shell penetrated 75 mm of homogeneous high hardness armour at 30 degrees from 800 meters. A 90 mm thick plate at the same angle was penetrated at point blank range. Subcaliber ammunition showed more impressive results: a composite plate made of 100 mm surface hardened armour plus 40 mm homogeneous placed at vertical was penetrated from 300 meters. From 80 meters the shell penetrated 100+60 mm of armour (also surface hardened and homogeneous respectively). 110 mm thick composite armour placed at 30 degrees could be penetrated from 800 meters.

Naturally, trials did not only show advantages. Since the S-54 used longer ammunition, it was harder to load the gun. There were complaints about both the traverse and elevation mechanisms as well as the brass catcher. More fumes were detected in the turret after firing. There were problems with balance. Nevertheless, the trials commission recommended the S-54 for production. The advantages were clear: the gun could be used in the stock T-34 turret and all existing tanks could be converted to use this gun. The commission suggested that any T-34 going through refurbishment should be upgraded. The commission also suggested that an analogous system should be designed to replace the weapons of the KV-1 and KV-1S.

Maximum gun deperssion.

It seems that the time had come to polish off the S-54 and put it into production. Even the arrival of 85 mm guns would not have stopped it. The GAU knew that the 85 mm gun was more promising, but it needed a bigger turret, while the S-54 could be used to shore up existing tanks. Unfortunately, the artillery branch dug in its heels once more by the start of December. The reason was the same: they did not want to put 3-K ammunition into circulation once more. The Chief of the GAU Colonel General Yakovlev himself spoke out against the S-54. He considered it an intermediate step at best.

Installation in the T-34's turret.

The finale was predictable. The decision to build T-34 tanks with a new turret and a 1600 mm wide turret ring was made in mid-December of 1943. This left the S-54 no chance of survival. The gun simply came into existence too late. There were also doubts about rearming the T-34 with a more powerful gun. Soviet industry did not like to do this. The story with the TNSh in the T-37A and T-38 is an exception, rather than the rule. 


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