Regimental Support Gun

The history of vehicles and weapons developed and produced in Leningrad in the summer of 1941 and during the blockade is an interesting topic for researchers. One of the most interesting parts are the improvised armoured cars, guns, and SPGs. Some of them are widely known, but others remain in obscurity. One such vehicle that became the foundation of the blockade SU-26 SPG will be covered in this article.

An obvious solution and non-obvious solvers

The idea of building an SPG on a truck chassis was pretty widespread in the USSR in the early 1930s. This resulted in the creation of the SU-12 SPG. It was meant to support moto-mechanized units and was supposed to become their primary artillery solution. The SU-12 was built on the chassis of either the Moreland TX6 or GAZ-AAA trucks. Instead of a truck bed, a platform with a pedestal mount and a gun shield was installed. The mount carried the oscillating part of the 76 mm model 1927 gun. These SPGs were built at the Red Putilovets factory, later renamed to the Kirov factory.

Images of the SU-12 SPG from the 1934 manual.

It's likely that this design influenced the creation of an an SPG that Kirov factory named Project 423. This project is unknown to the factory at this time. Documents contain only brief technical descriptions and no drawings or photographs at all. Interestingly enough, this rare vehicle was recorded on video. Comparing it with the description in documents makes it clear that this is indeed the Project 423. Earlier it was believed that the film depicted the SU-12.

The Leningrad VKP (b) municipal committee issued the decree titled "On producing the 76 mm model 1927 regimental gun" in early July of 1941. This decree organized widespread cooperation for production of regimental guns at Leningrad's factories. Kirov factory was put at the head of the process and was expected to deliver 400 guns in July.

Kirov factory did not stop at building towed guns. On July 27th, 1941, a description of Project 423 was composed at the factory. The description signed by department #4 chief L.I. Gorlitskiy and project lead V.A. Vishnyakov was sent to a number of recipients. The Main Artillery Directorate (GAU) was the only external organization to receive the letter. The rest of the copies were sent to other departments at the factory (SKB-4, SKB-2, MKh-9, the military representative).

Project 423: an SPG on a wheeled chassis designed at the Kirov factory.

The list of recipients allows us to theorize about how the project was developed. SKB-4 worked on artillery systems and was likely responsible for the gun mount and shield. SKB-2 built tanks, and was likely responsible for stiffening the truck chassis, which was necessary to fire the gun from it. The MKh-9 workshop was responsible for assembly, and the military representative would control the quality of the process.

At least two Project 423 SPGs were built, as shown on film.

The Project 423 wheeled SPG consisted of a mount with the oscillating part of the 76 mm model 1927 regimental gun and two DT machine guns installed on the chassis of the three ton ZIS-5 truck. The gun had a vertical range from -6 to +24 degrees and 240 degree traverse. Machine guns were mounted on the gun shield and could be aimed independently within a +/- 15 degree cone. The 6 mm thick gun shield protected the gun and crew from the front and partially from above.

Project 423 SPG on the streets of Leningrad.

The vehicle carried 45 rounds of ammunition in racks. 30 more rounds could be carried in crates. 18 magazines of 63 rounds each were carried for the machine guns with 1134 rounds in total.

The weight of the mount, ammunition, and crew added up to 2700 kg. The overall weight of the SPG together with the ZIS-5 truck was 5500 kg. The top speed on roads was 40 kph.

The SPG could be used to:

• Escort motorized infantry, cavalry, and transports.
• Attack enemy personnel and quickly change location.
• Fire on the move.
• Carry out typical missions of regimental artillery.

GAU representative at the Kirov factory Captain Gladyshev examined the progress of the work on August 1st, 1941, and reported the following to the secretary of the Leningrad VKP (b) municipal committee, Ya.F. Kapustin: "On the installation of oscillating parts of the 76 mm regimental gun on the 3 ton ZIS-5 truck [...] One gun with a shield carrying two tank machine guns in addition to the gun was installed. No ammunition crates installed yet."

SU-12 SPG on the Moreland TX6 truck chassis. The design and size of the gun shield are clearly different from the Project 423.

Captain Gladyshev listed a series of drawbacks: no armour for the driver's cabin, no seat for the loader, no window to talk to the driver in the back of the cabin. According to him, "These drawbacks must be resolved, since otherwise drivers will be hit often, the crew will have to work crawling around the floor, and work will be unproductive due to painful impacts; the vehicle will be uncontrollable". The military representative also thought that "it is necessary to remove the two tank machine guns from the gun shield and install one for the driver, as presently it is impossible to use the gun and machine guns at the same time."

On August 2nd, 1941, a letter arrived at the Experimental Artillery Scientific Research Proving Grounds (ANIOP) from the Kirov factory, asking to conduct trials of a 76 mm model 1927 gun mounted on a ZIS-5 truck with a supercharged round. It was mentioned separately that these would be factory trials.

An SPG with ammunition arrived at the proving grounds on August 2nd, 1941. The proving grounds described it as a "76 mm model 1927 regimental gun (barrel and cradle) mounted on a ZIS-5 truck in a special mount". A trials program was not composed ahead of time. It was improvised together with the chief designer, L.I. Gorlitskiy.

Trials included firing the gun in three positions relative to the truck's main axis at elevations of 0 and 24 degrees, 10 shots apiece. Supercharged ammunition with a wooden plug was used for the trial. Out of 30 shots, 28 were made from standstill and 2 more on the move, with the gun pointing perpendicularly to the direction of movement.

Positions of the gun during trials.

The gun mount was examined before the trials. Examination showed that if the gun is elevated by more than 20 degrees, the a portion of the sight's field of view (15 to 40 degrees) was obscured by the gun shield.

The following was noted as a result of the trials: "The rear window of the cabin covered with a metal shutter was shattered. The windshield cracked. The side windows shattered. The separating wall between the first and second ammunition racks in the left front corner of the vehicle broke. The lids of both bins fixed to this wall flew off. The left door of the cabin was smashed and the roof reinforcement ribs broke."

It was noted that "the damage was chiefly done when the gun fired at the 315 degree position. It is likely that the same thing will happen when the gun fires at the 45 degree position. " To safeguard the driver, the report suggested limiting the traverse of the gun mount.

When the gun was fired in the 180 degree position (position #1), the vehicle moved forward by 20-25 cm despite the handbrake being engaged. At 270 degrees (position #2) the left wheel of the truck jumped up significantly, but the vehicle did not move. The same thing happened at 315 degrees (position #3). At an elevation of 24 degrees and pressure of 24 atmospheres in the recuperator, the gun failed to return to battery by 15-40 mm.

Gun shield and gun of the Project 423 SPG.

The proving grounds composed its report on August 4th, 1941. On August 5th it was sent to the chairman of the GAU Artillery Committee. Copies were sent to the GAU Directorate of Land Artillery (UVNA), and the director and military representative at the Kirov factory.

At UVNA, the report was passed down to Military Engineer 1st Class N.G. Komarov. On August 11th, he added a comment: "This looks like a grassroots projects from the Kirov factory. No doubt, a mobile (self propelled) gun is needed, but this vehicle presentes too large a target. The prototype that was presented has a number of defects. We need to connect with this development and help out. At the same time, we should develop a system of SPGs, present it to the Marshal, and start working. Komarov" It is likely he meant Marshal Kulik, the former head of the GAU, who by that point lost his position. 

It seemed that the GAU didn't know about the work conducted at the Kirov factory.

Tracks instead of wheels

On August 26th, 1941, a decree of the Military Council of Defense of Leningrad titled "On transferring machine guns from the Kirov factory and creating a T-26 self propelled battery" was drafted. It read:

"1. Require director of the Kirov lifting and transport equipment factory comrade Moykin and military representative of this factory comrade Kurilenko [...] to restore and transfer to the Kirov factory 12 SPGs with T-26 chassis. Establish that out of the 12 SPGs, 8 should be assembled out of previously rejected parts and assemblies already at the factory. Due date: September 10th, 1941.

2. Require director of the Kirov factory comrade Zaltsman to install 76 mm regimental guns on T-26 SPGs and deliver the SPG battery to the Military Council no later than September 15th,1941.

Voroshilov, Zhdanov, Kuznetsov, Kapustin, Antyufeev"

The choice of the Kirov Lifting and Transport Equipment Factory was not an accident. Before the war, the factory participated in repair of BT and T-26 tanks in addition to civilian products. The workers were familiar with the design of these vehicles and the factory had the necessary metalworking equipment, assembly workshops, and lifting equipment for this work. The factory's warehouses already had some spare parts and even disabled or knocked out T-26 tanks of various types and years of production.

An article was published in the Tekhnika i Vooruzheniye magazine in 2019 stating that "in addition to that, the pilot vehicle with a gun on a mount with a shield was transferred to the Kirov Lifting and Transport Equipment Factory". Combining that statement with the above document lets us come to the conclusion that the pilot was delivered to the factory to copy the design and install the guns on T-26 tank chassis.

Production of SU-26 SPGs at the Kirov Lifting and Transport Equipment Factory.

Perhaps further investigation into blockade era designs will shed more light on this story. For now, we also know that Voroshilov factory #174 also worked on the T-26 SPG. This work is based on a decree of the Council of Commissars and Central Committee of the VKP(b) signed by Stalin in late May and tactical-technical requirements approved on May 27th by GAU Chief Marshal G.I. Kulik. 

The latter had a detailed description of the vehicles that were going to be built. According to the decree, factory #174 was to develop and produce the following vehicles:

• An assault gun (factory index T-26-6) with a 76 mm model 1927/32 gun on the chassis of the two-turreted T-26 tank. Two prototypes were due by September 1st, 1941.
• A tank destroyer on the chassis of the T-50 tank with a 57 mm ZIS-4 gun. A prototype was due by October 16th, 1941. Factory documents also mention the index T-26-7. There is reason to believe that the vehicle would actually be built on the T-26 chassis, but it's also possible that for some reason the project was given the name of another vehicle.
• A SPAAG (factory index T-26-8) with a 37 mm model 1939 gun. No due date was specified.

Documentation on the guns required for these projects and the guns themselves (two 37 mm ZIK-37 model 1939 AA guns and one 76 mm KT-28 model 1927/32 tank gun) were sent to factory #174 in mid-June. Additionally, the factory was loaned one T-34 tank with a 57 mm ZIS-4 gun by the ANIOP for study.

Documents confirm that factory #174 built two 37 mm T-26-8 SPAAGs and planned to have production blueprints finished by August 25th, 1941, when production would begin. The factory also at the very least developed blueprints for the 76 mm T-26-6 SPG, which was described as "KT tank gun in a turret". Alas, historians still have no information on what these vehicles would have looked like.

Strangely enough, the photo of the rare SU-26 was used to make this poster calling on workers to increase their productivity.

Trials of the SPAAGs were carried out at the ANIOP from July 19th to July 23rd, 1941. Factory #174 report dated August 12th, 1941, tells that the design of the 76 mm T-26-6 SPG is finished and the blueprints are almost done. Work at factory #174 on the T-26-6 coincides with work on Project 423. There is also an interesting note in the report: "Neither the NKSM or GAU gave direction on whether or not it is sensible to work on the T-26-8, T-26-7, and T-26-6. Letters to the NKSM, GABTU, and GAU about these projects are prepared."

By mid-August factory #174 would not have had spare T-26 hulls to make a T-26-6 SPG. This was the result of a direct order by Leningrad's industrial leadership. The issue of using existing T-26 hulls at factory #174 to build tanks was discussed on July 3rd, 1941, at a meeting of the defense commission. After that the existing hulls were counted and used to produce ordinary T-26 tanks. Since work on the T-26-8 SPAAGs began earlier, this decision did not affect them. The commission came to the following conclusions:

"1. Require factory #174 director comrade Markin to immediately begin using the 126 T-26 hulls and turrets located at the factory to produce T-26 tanks.

2. Production of battle tanks is due to begin on July 10th, 1941, with a quota of 70 tanks in the month of July.

3. Permit the director of factory #174 to use components and parts from the factory's mobilization reserve for T-26 production.

[...]

5. Control over the execution of this decree and technical assistance to factory #174 will be carried out by the secretary of the Leningrad machinebuilding municipal committee of the VKP(b), comrade M.A. Dlugach."

Industry management was in an interesting position once the war broke out. The State Committee of Defense (GKO), the highest authority in the USSR, was formed on June 30th, 1941. As for the factories, they were subordinate to People's Commissariats, but when the front line reached Leningrad its factories took orders from local Party authorities: the Leningrad VKP(b) municipal committee and associated organizations. Meanwhile, GKO decrees were still applicable to all levels of control. This put factory management in difficult positions when carrying out these orders.

The possibility that the front line would reach Leningrad was announced in early July, and a GKO decree issued on July 11th, 1941, proposed the evacuation of factory #174 to Chelyabinsk. Preparations for evacuation included partial breaking down of the equipment for shipping. On August 16th, People's Commissar of Medium Machinebuilding V.A. Malyshev proposed redirecting factory #174's equipment to Chkalov (modern day Orenburg). A meeting was held at the factory on the same day and preparations for evacuation were sped up. However, the Germans cut off the last railroad on August 29th and evacuation of personnel and equipment was only possible across Lake Ladoga or by air. Evacuation of workers and equipment slowed down, but never stopped. In these conditions factory #174 could no longer keep working on its old projects or put a whole new SPG into production.

On January 27th, 2021, the anniversary of lifting the Blockade of Leningrad, the Museum of National Military History in Padikovo unveiled a restored SU-26 SPG. This is a truly rare specimen, as no more than 30 vehicles of this type were built in 1941-43.

Clearly the design and assembly work described in the August 12th report did not come out of nothing. Work at factory #174 began in June and continued in July. It's quite likely that there was some division of labour. The Kirov factory developed the gun mount with a shield for factory #174 and then on their own initiative also installed it on the ZIS-5 truck. It is also possible that factory #174 transferred to the T-26-6 blueprints to the Kirov Lifting and Transport Equipment Factory alongside the sample gun received from the Kirov factory before evacuation. Unfortunately, this is not yet confirmed by documents. Factory #174 reported to the People's Commissariat of Medium Machinebuilding (NKSM) while the Kirov factory and Kirov lifting factory were a part of the People's Commissariat of Heavy Machinebuilding (NKTM). In this case, any cooperation between them would be reflected in factory documents, and archives of People's Commissariats and Party organizations.

As of today, we cannot conclusively say where the design of the SPG produced at the  Kirov Lifting and Transport Equipment Factory in 1941-43 truly came from.

Original article by Vadim Antonov