Buff My Tank: KV-1S/IS

Disclaimer: the contents of these articles merely illustrate the resources available for a historically accurate buff. This article does not imply that these changes should happen or will happen, either in combination or individually. Please pay attention to this disclaimer before being butthurt in the comments, thanks in advance. 

Earlier this week, I did an article on the KV-1 tank. I was going to do the Kirov trinity in one go, but the KV-1 had enough material to stand on its own. The KV-1S and IS are too intertwined, however, so they will have to share an article.

Let’s start with the small stuff: armour. The KV-1S actually has less armour than the KV-1, as the tank was supposed to be lighter. However, there were KV-1S tanks with as much protection as the KV-1. Due to a shortage of hulls, 70 KV-1Ses were built with KV-1 hulls. That’s a bit of a boost, I guess.

The IS can get a bit more of an increase. The IS tank in the game is an IS-2 model 1943, with the same zig-zagging armour scheme as the KV-1. The armour plating thickness was 120 mm at 60 degrees from horizontal on the topmost plate (effective 139 mm), then 60 mm at 16 degrees from horizontal (effective 217 mm), and then 100 mm at 60 degrees from horizontal for the lower glacis (effective 115 mm). On December 21st, 1943, the “autobounce shelf” was thickened to 70 mm (effective 254 mm). In June of 1944, a change was made to straighten the hull, much like the T-34′s, in what is known as “IS-2 model 1944″ (and not IS-2M, like it is erroneously named in so many English language sources). Both cast and welded versions of this hull had 120 mm of armour at 30 degrees from horizontal (effective 240 mm) and the same 100 mm at 60 degrees from horizontal on the lower glacis. Upgrading the hull to the model 1944 standard would increase the armour everywhere but that one thin strip of the hull that is presented at a very high slope. That’s an almost two-fold increase for the majority of the upper glacis.

IS armour schemes

The post-war modernization of the tank, which was actually called the IS-2M, also increased the ammunition capacity of the tank to 35 shells, but that’s another minor buff for a stat not many people care about. The top speed should be 37 kph, instead of 34 in-game.

The gun could get a lot better, too. The D-25T had superior accuracy (Edit: the dispersion of the shells was less, not combat accuracy, for anyone that confuses the two) and comparable penetration compared to the 88 mm L/71, even though it’s vastly inferior in both categories in game (SerB: “If we give the D-25 its real characteristics, there will be no tanks other than Soviet tanks left in the game“). However, that’s the gun that the tank actually had. This is World of Tanks. We can go further.

OKB-172 developed a gun for the IS and KV tanks (the date on the document indicates that this was most likely the KV-1S) known as OBM-51, ballistically identical to another gun, the OBM-50. These names probably don’t mean anything to you, but you should know the gun by another name: BL-9.

That’s right, the top gun on the IS-3 tier 8 tank was historically built for the KV-1S, a tier 6 tank. But it gets better. You know that gun the IS-4 has that’s entirely ahistorical, the M-62-T2? Did you ever wonder why it has it? Historically, the gun replaced the D-25T on the IS-8. The plan was to use that gun as a replacement for all D-25T guns, on every tank. This includes the IS-2, and, since the KV-1S could take the IS-2 turret, KV-1S.

Bam. Tier 10 gun on tier 6 tank, or a tier 7 tank with 240 mm effective armour on the front. So the next time you complain how the KV-1S is made up of Russian Bias, think about how bad it could have been if SerB was really out to get you.

Edit: oh, and I guess that autoloader thing, but really, the M-62-T2 is in the same realm of realism here, so who cares.

Edit 2: oh, and also a 152 mm gun, but there aren’t any specifics on that one.

118 thoughts on “Buff My Tank: KV-1S/IS

  1. The single piece upper plate would just mean you only shot the lower plate (or the turret), instead of avoiding the trollish stepped plate in the middle.

    The M-62-T2 would be hilarious on a KV-1S.

  2. You know EnsignExpendable, The_Chieftain and I have said this before, but mind putting at least some integrity into your articles?

  3. The accuracy of the D-25T IS realistic! It’s just that the gunner is handed a shot of vodka every other shell…and he practices right before you load in…a lot…

  4. Always wanted the KV1S to have IS6 armor values and stomp people in T6 games even harder than it does now… Can we pretty please have a faster reload and better aimtime for the 122mm gun, to go with that armor PLEASE ?????
    Thought SilentS was mad for writing this… but after reading Daigensui’s comments I realized this was written by EE and I was glad i only briefly looked at the posted picture and skipped the text. Thx for wasting 5 minutes of my life douche… No pubbies to troll ingame tonight ??? Did you get banned from too much TKing or something ??? Do you have like a 7 day RO on NA forums ???

    P.S.: F**K goons… you ruin everything…

  5. I hope you’re trolling. There aren’t many other tanks in WoT which are as OP as KV-1S. It should be nerfed, and HARDLY, not buffed.

  6. I think this is doable, for both KV-1s and the IS.

    In their top configuration, as mentioned here, they could have limited MM i.e. KV-1s limited to T8 battles only and the IS to T9 battles only (but should still be considered in their respective tiers).

    • well that would fix many of the problems, the module-based MM

  7. Yeah, give D-25T it’s historical COMBAT accuracy and COMBAT ROF – up to 3 rounds per minute on IS due to separate projectile and charge, we will see those herds of Russian tanks.

    • Separate projectile and charge do not inherently make the rof lower .. The challenger has an rof to all of it’s contemporaries .

    • With big shells separated ammunition tends to be the *better* option as the loader doesn’t have to wrangle an excessively large and heavy unitary cartridge, you know. They did experiment with the latter in the T-44-122; didn’t exactly pan out.

      • My favourite was the 95 mm gun in the T-28 turret, where the length of the full shell was larger than the turret diameter minus breech length, so it had to be loaded diagonally.

        • …ouch. Waitwhat, *95*mm? Did the Soviets even have a gun like that? I know there was a 85mm one and a 100mm one, but…

  8. Buff my Tank becomes SS’s own trolling channel? It seems to. Propose buffs for the most OP tanks in the game. I hope next time you’ll write about some kind of laser cannon on the IS3. Ridiculous.

  9. Thanks for the article EnsignExpendable, it was interesting read. I am quite surprised (in a good way) and value you for the fact you continue in your work despite the herds of idiots that cannot process written text.

  10. Hey EE, Zaloga in his Osprey book about Soviet heavy tanks mentions a 203mm howitzer in a turreted KV series chassis (no further details given but I assume it’s at least KV-3 or bigger) when an attempt to create a new KV-2 like tank was discussed, do you know anything about that?

  11. you know guys.. even if WG gave these 2 some of these buffs, they won’t be at their tier anymore. would you really think that IF (and I say if.. I read the disclaimer) they give the kv1s the better gun and armor it will stay at tier 6 so you can pwn even easier? get real

    if both kv1s and hellcat are far from their historical counterparts.. why dont they just buff them and move them a tier or 2!

  12. Buff the KV-1S and/or IS!?

    ROFLMAO!!! That’s the best joke I’ve heard from you yet! XD

  13. EE, don’t listen to butthurt trolls, who don’t even want to understand what these articles are all about. For me it is always interesting to find more historical background to the tanks I play/played. Jus’ keep ‘em comin’. :)

  14. Things always appear better on paper than in the real world, especially Russian equipment.

  15. Ty EnsignExpendable for this article. Now im glad that the kv1s is just “normal” op :-D
    Plz dont listen to the disclaimer ignorants and keep posting this stuff.its funny to read :-)

  16. TBH, if the D-25T were less derpy but had worse RoF (you know, because Soviet midget tankers cramming two-pieced 122mm ammo into the breech while inside a rather cramped turret), it would be a lot better balanced- currently, it utterly murders lower tiers (and many equal tiers) with its crushing damage output, but struggles when it can’t bully weaklings because it has problems actually *delivering* that damage to anything with good armour.

  17. Place KV-1S at t8 as a premium, give it the t10 122 mm… Instant hightier swarm and lots of $$$ to WG.

    Or maybe not :p

  18. You keep using that table. I don’t think you know what it means. (Hint: purely theoretical)

      • There’s plenty of penetration tables that are made after actual firing tests. This ( http://2.bp.blogspot.com/-GHXEF_0RwAU/UTJZkUOH60I/AAAAAAAAAF4/TalwxzLN9UM/s1600/probivbaemost.gif ) is purely mathemathical extrapolation by a group of Soviet engineers, who did not have access to German guns. This is evident from that the table is perfectly consistent with calculated figures (tested myself).

        This leads to some errors that reveal that no actual German guns were fired to make this table. Pen figures for German high-end guns are generally much too low. 75 mm KwK 42 MV is too high – not actually measured, and this error reflects in too high pen when compared to other German guns. Different shell types don’t register in any way, thus Soviet uncapped sharp-nosed shells get precisely same pen figures as German old-fashioned uncapped AP shells (short 88) and newer, more efficient APCBC shells (long 88) for given shell size and MV.

        You’re making disservice for everyone in the hobby by disseminating this table as authentic gun performance indicator.

          • What tests? Never seen any source giving anywhere near that low pens for German guns as this, the recent go-to table for justifying low German pens in WoT which has zero infromation value regarding them. I can pretty much guarantee none of them are western.

            • Given that there’s huge relative disparity between Kwk 42 and Kwk 44 pens due to clearly false data in the table, it CAN’T “work out” with any actual testing data. How big is your acceptable margin of error? 35%?

            • So I was right. Quit ye trolling, didn’t say they don’t count. Rather that I know western tests way better than eastern and none of them give such results. Is that to say that western sources consistently and intentionally exaggerate German gun performance?

              Any links to actual Kubinka and Gorohovets test tables?

        • The Soviet data on that table are confirmed by other archive data. It’s the foreign data which doesn’t match any other source. Take for example the 85mm APBC, 57mm APCR and German 75mm AP Model 40. In yugo data they all penetrate the same about 100-105mm at 1000m. It’s not about hard or soft armor either as yugo tested against both hard T-34 armor and soft Sherman armor and the test results were all the same. Look at the table German 75mm M40 only penetrates 74mm. What gives with that disparity?

          • As said, German guns weren’t actually test fired. Figures given for them are estimates calculated based on older Soviet uncapped AP shells. This disregards that German AP shells were different, giving better penetration for energy and better velocity over range. These were Armor-Piercing Capped Ballistic Cap shells, also known as Pzgr. 39. Soviets partially moved to this shell type over late-war years.

            This is evidenced by German short 88′s performance figures closely matching to older uncapped shells used in early war. Later APCBC shells for the gun give better performance.

  19. Honestly, I can’t see why people are getting so mad here.. It’s meant to be entertaining and satirical by showing us what Wargaming *could* have done but chose not to.

  20. You completely see it the wrong way.
    Not a tier 6 tank with a tier 10 gun at tier 6 but a tier 6 tank with a tier 6 gun at tier 10.
    Or would you put the upcoming German tier 9 TD at tier 5 because it’s based on a Panzer IV?
    Or US tanks, T29 was able to mount the 155mm gun so why not remove T34 and T30 and let there be more gun upgrades for the T29.

    So please stopt this “tier 6 tank could carry tier 10 gun at tier 6″ bullshit.
    Tier 5 KV was split into tier 5 KV-1 and tier 6 KV-2 because it’s top guns did not match it’s tier and the same may happen to KV-1S, they could easily make two tanks out of it and put the one with the 122mm gun at tier 7.

  21. You mean creating a game that highlights the russian strengths and none of their weaknesses? I’m all for historic additions but I would like to also see historic accuracy too. Like… the armor increase with the KV-1s’ top turret is ~20mm all around but yet only a 600kg gain in weight and no loss is transverse speed? Its top and largest gun has more angle depression than its smallest gun and double of what is listed in most spec materials. There are a lot more bizzaro world examples with just the KV-1s, not to mention with the entire line.

    • I would like to see implemented a type of crew fatigue. In WarThunder if you pull several Gs in a turn, the pilot gets tired and less capable of pulling another one. He looses accuracy and is more likely to be wounded if shot. This could bring in WoT the main weakness of Soviet tanks which was crew comfort. They could have more of their historical stats but make the RoF decrease over time because the loader would get tired, the accuracy drop because the gunner would strain his eyes over time, the view range decrease because the commander can’t focus as well, and the tank less responsive to quick manoeuvres because the driver can’t pull those damn levers all day with the same force. Make it like this for all vehicles with a coefficient that decreases crew performance with increasing time in battle but give uncomfortable tanks a worse coefficient because this reflects the downsides of having compact designs with big guns on them, and rewards smaller guns on bigger, more comfortable platforms.

      • A lot of interesting crew skills and perks could be tied into this as well. Hm, maybe there’s something for an article here …

      • Not quite sure the well-known and potentially quite immediately dramatic side effects of high-G turns – in Korea dogfighting jets were apparently quite often temporarily out of control due to the pilots blacking out – much compares to long-term crew fatigue in tanks…

  22. Soviet tanks are so op in real life, if they made them historical in game it would be unfair.

  23. Real characteristics?
    According to DDR 1960 firing table the D-25T MV0=781m/sec. Penetrates 160mm @ 100m.
    Mean dispersion @1000m = 30cm x 30cm = 50% dispersion: 50.7cm x 50.7cm.

      • This table is mentioned quite a lot (if u search for ddr penetratation table D-25-t), but most websites (which host(ed)) the image have it hidden or removed,

        fun fact, Panther has 188-190mm penetration with the L70, so if D-25-t needs a buff so does the L70 :XD (us test from after the war, german ammo was better, thus for same mv / ke better penetration

        • found it:


          so please stop the bs about the derpy 122mm having better penetration as L71 aka the best gun of the war…

          Also GUN accuracy has NOTHING to do with actuall performance…. (give the best gun of the world to an idiot and its still useless) also those tests never show how that 122mm would far after driving 3 hours in a crappy, hot, stinking tank, which gets filled with smoke after u fire once, while TRYING to hit something with ur crappy optics…. (those optic “myth“ was also pure bs, everyone except ussr (hurr hurr) says german optics where far better, till the END of ww2, to quote some1:

          In Parola armoured museum the StuG III has a plaquate next to it were tanker veterans say StuG III (or “Sturmi” as it was called in Finland) having the best optics in any tank Finland used until T-72 came to service. The StuG III remained in service as a training vehicle spesifically for the excellence of the optics until late 1960′s. The praise goes spesifically to the clarity of the vision. So for 30+ years none of the Soviet or British tanks used by Finland had according to these veterans even same quality optics as the lowly StuG III

          while german (and american) “war story`s“ are biased, same goes for ussr, and im some ways even more…. (the ussr was built on lies after all, even more as “the west“)

          • Yeah, well. Finland also got a few Pz IVs – one later got to play a KV in the filmatisation of “The Unknown Soldier” – so by that logic the StuG’s sights beat those, too.

            • …which is why the Soviets switched to a three-man turret later. However the topic here was *optics* not labour distribution, pay attention.

            • Are you just like every other commietankfangirl and suggest that superior optics alone will automatically make you able to see better, further, and more of everything all the time? Optics is just one part of a larger system that is good as its weakest component. You should pay attention yourself.

              He quoted from a report and I think its important to read everything else in it too because that snippet was about only good thing they had to say about the T34 and KV. Its amazing how many things they had to fix later.

            • It is quite correct that any system is only as good as its weakest part, but that’s not really the topic here. Which is that contrary to what (the other?) Anonymous above tries to claim that wasn’t the optics themselves in this context.

              How about you actually check what’s being discussed before getting all pissy offtopic?

          • Do I need to point out that a shell that large and heavy doesn’t need to “properly” penetrate to seriously fuck up a tank? (And that’s without going into testing crietria and definitions of “penetration”…) The Soviets certainly considered it powerful enough that a more potent replacement wasn’t deemed necessary either during or for a round decade after the war – and these were the guys who were looking into putting a 100mm gun into a medium tank already in the late Forties.

            • That blog is wrong.
              Soviet WWII penetration criteria is 75% of the shell mass passes through the armor.
              Nothing like that occured.

              It might however qualify for a US protection criteria penetration as fragments might have been able to penetrate a thin aluminum sheet behind the armor.
              See section A-1

            • a few reasons it doesnt proof much:
              - ferdinand was 100mm armor with 100mm welded on top of it, so MUCH weaker as 200mm plate (more like 150-160mm if it was 1 piece of steel)

              exanmple (too lazy to get my mechanic book and read it all over again) but it comes down to: 1 homogenus plate is much more resist to all sorts of bending and twisting as 2 plates on top of eachother, no matter it its wood, steel or whatever, and also the way its connected doesnt matter (glue, screws, welds) it keeps weaker

              - that ferdinand was most likely put on fire, and fire destroys steel fast, very fast, a steel structure looses 90% of its strenght of heated too 800 degrees (c), which is easy reached by an engine fire, a lot fo strength will be gained back when it cools down, but it will most likely become brittle, welde might crack or weaken due to thermal expansion + the quality of the steel drops

              ps: it even depends on the type of steel, i know from construction work that pre-stressed steel bars, once heated above xxx degress (c) loose virtually ALL strength once cooled down.

              so instead of 200mm high quality armor it was more like 150-170mm armor with doubtfull quality + big chance they shot multiple times and all in all it doesnt say much

  24. IS-2 model 1944 is called IS-2m and the post-war modernization is called IS-2M.

    Are you sure IS-2m is incorrect? I know soviets used to say tank + model + year + factory


  25. I guess we may possibly see the obr. 1944 hull when hull upgrades come to World of Tanks. I look forward to the day of having a reliably bouncy upper glacis on my IS.

    • Oh, correct me if I’m wrong, but I recall reading on battlefield.ru that it was originally intended that the upgraded hull use a 100 mm rolled plate, but they ended up using cast armour, so they made it thicker to compensate for the lower quality of casting. Is this correct?

      The Chinese IS-2 uses a 90 mm plate for the same configuration, not sure how historical that is.

  26. a buff to the KV1s??? really???? Fuck off!!!! it needs a huge nerf and preferential MM , like from tier 6 above only!

  27. oh wait, did i say nerf? i meant “rebalance” just like the VK36.01H got “rebalanced”