Cold War Soviet Heavy Tank Prototypes

IS-7 (Object 260)

Soviet Union (1946-1948)
Heavy Tank – 7 Prototypes Built

The IS-7 (ИC-7), starting life under the project title of Object 260 (объект 260), followed on from the ill-fated IS-5 (Object 730) and IS-6 (Object 252/253). With these failures, the request was still standing for the USSR’s next heavy tank.
The IS-7 was the brain-child of the Soviet tank designer Nikolai Fedorovich Shashmurin. As well as having a hand in the design of the rather successful IS-2 which would serve well in the later years of World War II, Shashmurin also drew up plans for the ill-fated KV-4 (Object 224) project, which never came to fruition.
The IS-7 would be Shashmurin’s crowning glory and could be considered the zenith of the Iosif Stalin heavy tanks. At the time of its conception, it was one of the most technologically advanced heavy tanks in the world, and one of the most heavily armored.


The seeds of the IS-7 were first sown in December 1945 in Factory No. 100 in Leningrad, with a full-scale wooden mock-up produced soon after. Running prototypes were ready for testing in 1946. These tests ran through 1947, ending in 1948 when the designers believed they had reached a finalized design. It was then given the title of IS-7. This final design was armed with a stabilized 130 mm (5.12 in) cannon fed by an autoloader, a total of 8 machine guns, infrared scopes, and armor up to 300 mm (11.8 in) thick. It was the largest tank that the USSR had or would ever produce.
The wooden mockup of the IS-7, at this point known as the Object 260
The wooden mockup of the IS-7, at this point known as the Object 260


The tank was designed to withstand the impact of a shell fired by the 12.8 cm Pak 44 Gun found on the German Jagdtiger. The armor on the IS-7 was up to 300 mm (11.8 in) thick, some of the thickest being found on the specific pike nose, formed from homogenous steel. The upper plates were 150 mm (5.9 in) thick angled at 60 degrees. The lower glacis 100-120 mm (3.94-4.72 in) with a slight angle.
Rear cutaway view of the IS-7. Note the thicknesses of the armor on the turret and hull sides.
Rear cutaway view of the IS-7. Note the thicknesses of the armor on the turret and hull sides.
The side armor was also not to be underestimated. The upper hull was 150 mm (5.9 in) thick, while the lower sides measured 100 mm (3.94 in) and was curved outwards, meeting the upper hull seamlessly. The bending of the lower hull was done in a large press, which literally forced the metal into shape.
The mantlet was 350 mm (13.8 in) thick. The turret itself was cast, with the cheeks being the thickest part at 240-250 mm (9.45-9.84 in). They were angled, or curved, at about 50-60 degrees. The shape of the turret was extremely rounded and smooth all the way around, with no obvious shot traps or prominent cupola. There were slightly raised portions of the turret roof where crew positions were found. The commander’s station on the right was slightly higher than the gunner’s one found on the left. The top of these raised portions had direct vision blocks.
In a hull-down position, the turret would have been almost impenetrable. The armor proved not only immune to the intended 12.8 cm, but also the tank’s own 130 mm cannon.


The IS-7’s main armament consisted of the 130mm (5.11 in) S-70, although it was originally intended to carry the S-26. The S-70 was derived from a naval gun. It had a barrel length of 54 calibers. The gun could fire a 33.4 kg shell at 900 m/s and was able to penetrate up to 163 mm (6.4 in) of armor, sloped at 30 degrees, at ranges up to 2000 meters.
The 130 mm S-70 gun with the coaxial KVPT on top.
The 130 mm S-70 gun with the coaxial KVPT on top.
As mentioned above, the IS-7 was equipped with an autoloader. It is not an autoloader in the current sense of the word, however. A more accurate description would be an Automatic Loading Assistance Device, that would be operated by the tank’s two loaders. This piece of equipment was located in the turret bustle. The ammunition of the IS-7 was composed of two parts, separately loaded. As such, the charge was at the bottom of the device, while the projectile sat above. It was operated by a crank handle. The first turn would drop a projectile onto the conveyor belt located in the center of the system, a few more turns would drop the propellant behind. The conveyor would then carry the ammunition to the mouth of the breach, where it would be rammed in. The conveyor would then lift clear of the gun. The gun then fired and the process began again.
The IS-7s loading system
The IS-7s loading system.
This theoretically gave the tank a 6 to 8 rounds per minute rate of fire. Whether actual operation matched this time is unknown, as it doesn’t take into account the reloading of the device. However, it could technically be resupplied as it worked from the various ammunition racks inside the vehicle. The tank carried 25-30 rounds. The downside of this system was that the gun had to return to a neutral position for the loading device to work, meaning the gunner would have to re-lay the gun onto to a target after each shot. Should the mechanism go down, the gun could be manually loaded of course.
To say that the IS-7 was lacking in secondary armament would be an understatement of the highest order. The IS-7 was equipped with no less than 8 machineguns. Four of these were 7.62 mm (0.3 in) SGS-43s and they were mounted in a unique way. Two were placed on both flanks of the hull, towards the rear, fixed in place and fired by the driver. The machine guns were housed in a simple armored box. There were separate shoots for the spent casings and belt links. The ammunition was stored underneath.
There were two more of the machine guns fixed on the rear of the turret, facing backward. These two were staggered to accommodate the large ammunition shoots on the turret roof. Sheet metal boxes were attached to the outside of these to collect the belt links, but casings were left to fall away. It is believed these guns were operated by the gunner or loader who would take aiming orders from the commander to turn the turret left or right. The practical use of these weapons is highly questionable. Whether they would have stayed on a production model is unknown, but some of the prototypes were not equipped with the ones on the turret.
The roof was home to a 14.5 mm (0.57 in) KPVT heavy machine gun on an AA mounting that could pivot down to the left when not in use. The only way to operate this gun was by standing on the engine deck. There were tests to see if it could be remotely controlled by the commander, but these were unsuccessful.
The IS-7 had no less than 3 coaxial machine guns. As well as the KPVT mounted on top of the main armament, 2 SGS-43s were mounted either side of it.


The IS-7 was powered by the M-50T 12 cylinder diesel engine, rated at 1050 hp, and was derived from a naval marine engine. It would run through an 8-speed planetary gearbox. This would propel the vehicle to 60 km/h (33 mph) on roads, a respectable speed for a tank weighing 68 tons fully loaded. Spare diesel fuel could be stored in canvas pouches in compartments towards the rear of the vehicle on each flank.
The weight of the IS-7 was supported on 7 roadwheels on each side. These wheels also supported the return of the track, as there were no return rollers. Each wheel was attached to a road wheel arm, in turn, attached to the torsion bar suspension. The wheels had internal rubber bushings to give the all-metal wheels an extended service life.
The tracks of the IS-7 were some of the first in Soviet use to have a retaining clip in the track link pins, instead of having to rely on a wedge of metal welded to the lower hull to whack the pins back in.

Photo: – Alexey Khlopotov


After the initial factory tests, the prototype tanks were handed over to the State Commission. The test drivers were famously fond of how the IS-7 handled. Reporting that it would respond to the smallest adjustment with ease. The tests were not without incident, though.
During one of the trials, an IS-7 caught fire, despite both sets of internal extinguishers firing, the fire continued to burn resulting in the abandonment of the vehicle and its complete destruction. The cause of the fire was thought to have originated with the weight-saving plastic lined canvas fuel tanks. Quite understandably, these were deleted in later versions.
Though it was liked and generally thought to be a good vehicle, the governing bodies refused to accept it into mass production. The official reasons are not known as to it was rejected. As such, the IS-7 would never enter service, with its successor, the IS-8, later known as T-10, proving to be a more flexible vehicle and able to better meet the needs found on the now fast moving battlefields. It served from 1953 to 1996.
Only one IS-7, built in 1948, survives today and is currently on display at the Kubinka Tank Museum.
The IS-7 as it stands today in the Kubinka Tank Museum
The IS-7 as it stands today in the Kubinka Tank Museum, alongside the IS-4.

Planned Variants

Object 261

While work was ongoing with the IS-7, plans were drawn up for a self-propelled gun variant based on the IS-7’s hull. There were 3 planned versions, the Object 261-1, -2 and -3. The 261-1 was a closed type with the fighting compartment on the bow end of the vehicle. It was armed with a 152 mm (6 in) M-31 gun. The configuration was similar to the ISU series.
The 261-2 had a rear mounted open fighting compartment. For this version and the following, the chassis was reversed, meaning the drive wheels were now at the front of the vehicle. What was the IS-7’s front was the 261-2’s rear. It was armed with a long-barreled M-48 152 mm (6 in) gun. The Object 261-2 was later redesignated Object 262.
The 261-3 had the same configuration as the 261-2/262, but was up-gunned with the naval derived 180 mm (7.09 in) MU-1 gun, also known as the B-1-P. Despite them being Self Propelled Guns, designed to be behind the lines giving fire support, these vehicles were intended to be well armored, with armor 150 to 215 mm (5.91-8.46 in) thick. The vehicles didn’t go further than the scale model phase.
The small-scale mock-up of the Object 261-2/261-3
The small-scale mock-up of the Object 261-2/261-3. A Recoil-spade was also added to the rear.

Object 263

This was a tank destroyer variant, built on the same configuration to the 261. It had a rear mounted, semi-open fighting compartment. The main armament was the 130 mm (5.12 in) S-70A, with separately loading ammunition. This was a slightly modified version of the IS-7’s gun. The armor was up to 250 mm (9.84 in) thick, with a large, flat slab on the front of the vehicle, and two plates either side of the gun mantlet. The side armor was up to 70 mm (2.76 in).
As with the 261-2 and -3, the IS-7 chassis was reversed, a configuration similar to the British Archer. The driver was moved to the left of the gun. Whether the 263 would have had the same issue of the Archer’s engine heating the middle of the barrel and throwing off accuracy is unknown. Like the 261, the vehicle never went further than small scale models.
The small-scale mock-up of the Object 263
The small-scale mock-up of the Object 263. The 263 also saw the addition of a recoil-spade on the rear.

An article by Mark Nash

IS-7 (Object 260) specifications

Dimensions (L-W-H) 7.3 m x 3.3 m x 2.4 m (24ft 2in x 11ft 1in x 8ft 1in)
weight 68 tonnes
Crew 5 (driver, gunner, 2x loaders, commander)
Propulsion 1050 hp 12 cylinder M-50T diesel engine
Suspension Independant torsion bar
Speed (road) 60 km/h (33 mph)
Armament 130 mm (5.11 in) S-70
2x KPVT 14.5 (0.57) MGs
6x SGS 7.62 (0.3 in) MGs
Armor Hull: 150 mm (5.9 in, upper glacis, angled at 60 degrees) – 100-120mm (3.94-4.72 in, lower glacis). Side armor is 150 mm (5.9 in) – 100 mm (3.94 in).
Turret: 240-250 mm (9.45-9.84 in)
Total production 7 prototypes

Links & Resources

An article on the IS-7 on FTR
An article featuring the IS-7
The above link uses the following literature as the primary source: Heavy Soviet Post-War Tanks. Written by M. Baryatinsky, M. Kolomiets and A. Koschavtsev. “Armour Collection #3, 1996”
The IS-7 on (Czech)
The IS-7 on (Russian)
English translation of the article

Illustration of the IS-7 by Jarosław Janas
Illustration of the IS-7 by Jarosław Janas.

Illustration of the IS-7 by Tanks Encyclopedia’s own David Bocquelet.

By Mark Nash

Member since 2016. Specializes in weird. 120 articles & counting...

35 replies on “IS-7 (Object 260)”

I was looking at description of the IS-7 and I noticed that next to 130 mm that it said (3.94 in) if I’m not right that should be 5.11 in or 5.12 in?

THIS TANK IS A MONSTER!!!!!!!!!! And with an autoloader for the gun! Impressive!

There is a long article translated from Yuri Pasholok’s blog about the origins of the IS-7, especially its direct link to the IS-6, that could be used to deepen the introduction of this article: (
To make short, the origins of the IS-7 comes directly from the IS-6, opponent to the Objekt 701 (future IS-4) as replacement of the IS-2 (and finally, it’s the Kirovets-1 that was selected …). The IS-6 was not selected, but work this project continued, giving the Objekt 252. The project evolved, gave the Objekt 257, evolved again, giving the Object 260 that finally was the last precursor to the IS-7.
See also:

The Yuri Pasholok article is already a source of this article, but I shall look through the other ones, thanks.
-TE Moderator

pity this tank never saw service. It would have been a match for the M60, probably.

Depends on the type of ammo fired at it from the M1, but it is likely that it would penetrate.
– TE Moderator

8 MG really? just why you need that many guns?
1 or 2 mg on top turret manned by commander or any available crew
plus another MG beside the main gun is already enough!

If you read closely, I believe it was actually ten. 4 fixed on the chassis, 2 on the turret facing rearward, 1 in an AA mount, and 3 coaxial. However, I think they only listed eight because the two on the turret rear were never actually fitted and only existed in deigns.

no the 2 on the Turret where fitted check Inside The Chieftains Hatch when they cover the IS-7 when you see him going over the tank you see the 2 forward 2 rear on hull 2 rear facing on the turret the the coax and the flex mount on the turret i dont remember him discussing the 2 smaller co-axial mounted machine guns

i mean if you look at the height of the Flex Mount the person using it would be full on exposed to enemy return fire like i mean i can understand the 2 on the rear of the turret and the coax 14.5 but the hull mounts i dont really understand maybe its just Russians like Dakka just like the Americans do lol M3 Lee, Early model M4 Sherman’s, M2 Medium machine gun fire intensifies

Maybe the Russians wanna kill themselves, That’s my guess for why the machine gun is so high up.

(Although that isn’t the reason I guess they would probably later add a cover or shorten it or it could be used to make the beast more intimidating.)

and why it has so many machine guns? I guess the soviets were paranoid about their expensive heavies being taken out by infantry with RPGS which is also unlikely because the ones on the hull look like they cannot move much to deal with such a threat)

Russian designers and their motives are mysterious a lot of guesswork is involved is needed and questioning due to the lack of information and secrecy of such projects, Also I think if they were able to make the IS-7 hold more ammo make it a little more mobile, and if the high command and politicians stuck the 55-ton limit up their a** and weren’t so paranoid and liked making things cheaper and continue on with more basic designs like the t10, for example, I truly think the IS-7 if it had been researched and tested and gave a little more time it would’ve been a very very good heavy tank So much wasted potential!

Soviet tanks tend to have a very long and complex development history. This makes writing Soviet articles quite time-consuming. The language barrier can also be an issue. It will get done eventually.

Does it actually have a connection to the Object 730? Because from what I can tell development on that started in 1949, way after the IS-7.

I’ve tried to study the chronology of the IS series designations and my best guess currently is that the IS-6 got its name because it was developed after the Object 248/IS-5. And even though the 248 was cancelled before the start of the IS-7 they simply continued on the numbering past the 6. Later the 730 got the IS-5 designation because it was meant to replace the IS-3 and 4, and the 248 was probably forgotten by then.

To add further and explain the timeline, the IS-6 recieved its designation in june 1944 while the IS-3 received its in december 1944. Likely because the Object 244 (IS-3), 245 (IS-4) and 248 (IS-5) were cancelled in october ’44.

Also also. I would very much appreciate if the article also included more information about the projects early days (1945-46) when it still looked like that wooden model and was equipped with the 130mm S-26.

the reason why the IS-7 had 4 fixed machine guns was for psychological warfare; the theory was that, when these guns were fired, the tank would seem more formidable to the infantry, hence lowering their morale and making it easier to win the battle.

Could the IS-7 have a different MG or autocannon on the AA mount? This would’ve made it very versatile in infantry fighting and AA duties.

Perhaps the IS-7 was the last rank of the IS heavy tank but now that place is replaced by the T-10 heavy tank, but the IS-7 is also not the medium form because it has the S-70 cannon. This caliber 130mm is even larger than the D-25T 122mm cannon for IS-2 heavy tanks, D-25 122mm for IS-3 heavy tanks and D-25T 122mm for IS-4 heavy tanks, says For easier understanding, the cannons of these three tanks are completely weaker than IS-7 because IS-2, IS-3, IS-4 only have 122mm caliber and IS-7 130mm. The cannon of IS-7 is more than capable of penetrating the front armor of Panther, Tiger and King Tiger tanks, and in terms of destructive power, it is not discussed. IS-7 has a mass of 67 tons, 150mm thick armor of 65-degree steel inclined, a maximum speed of 60km/h and a shell weight of 33 kg, everyone can imagine its strength and ability to “strike” already. there. The armor is also more than capable of resisting Jagdtiger’s 12.8 cm Pak 44 bullets at a distance of nearly 1 km. In addition, it is also known as Object 260. This super product is stronger than that IS-2 of course, but can it withstand the shells of Panzer-Force anti-tank artillery or not? If not, I don’t know but it certainly is, but depending on the type, the rate it can resist the ammunition of the Panzer-Force anti-tank gun is very little because the Panzer-Force anti-tank gun destroyed many IS-2s. of the Soviet Union.

And it’s a pity for this super product because it was replaced in 1945 and made room for the T-10 tank, but the IS-7 is still considered one of the valuable weapons on the battlefield. In addition, it is also known by a nickname that very few people know as “The King of Heavy Tank IS-7).

Perhaps would you like an accurate 3D model of the IS-7 and object 263 and 261 and if you’d like a loading animation. I can probably make this within a month or two if I work on it an hour a day, Its is harder then you’d think when I first started 3d modeling their textures are very hard to master if you add weathering dirt and over stuff that goes into a tank and (ever so merciful to 3d designers) soviet designers with their rounded vehicles although since this is more flat it will be a hell lot easier to do

(Had to ask my friend Klaus to translate this into English)

Frieden aus Kassel Deutschland,
Hannah, Focker

this is what i remembered from the official documents on my hard drive (Destroyed when my laptop caught on fire) I didnt put what I didnt remember clearly but I put what I knew for a fact.

you guys are right on how the drivers are fond of the steering and the source of the fire was indeed the canvas oil (probably from the engine) leaked onto the canvas and the heat lit it up and why the fire didnt get put out was because the extinguishers didnt reach the fuel tanks and pretty much only covered the engine Plus it actually fired 5-8 rounds per minute not 6-8 (Depending on how fast the loader puts it in obviously and how quick it takes to put it back into nuetral) the official statement for it was that it was a good tank but they refused because of the high weight and doubts about its complicated loading system but apparently the document said it could penetrate 180mm of steel armor at 30 degrees not 163 in the higher gears it got a little stiff but overall the IS-7 proved during testing a really good tank.

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