So I recently got the K-91-PT from the battle pass because I'm a masochist and I like playing the weird tanks nobody else enjoys. I've played it for some games, and I've enough information to give a little rundown of the tank, in case anyone else is thinking of also getting it.
The Disclaimer
Straight from the off, I'm just going to say it – if you want a generally good tank, pretty much everything else on offer from the Battle Pass is easier to play, even the worse tanks like the 777 II. The Kunze is also much easier just to pick up and play. The K-91-PT requires alot of knowledge on where exactly you can use it to get the most out of it. The rear mounted gun, lack of turret, bad gun depression and wonky gun handling all work against you, so you have to know what you're doing to use the tank properly. Luckily I am a fan of the Chinese mediums and the rear mounted soviet medium line, so I'm used to most of these downsides.
But you've been warned – it's a very hard tank to play.
The Gun
So the gun is what probably puts most people off getting this tank – it has horrendous gun handling for a tank that only has 390 alpha. This is made even worse by the fact you don't have a turret. The rate of fire is nice (on par with Tier X mediums with 390 alpha) but it's not absolutely spectacular. You can usually outmuscle equal tier tanks outside of the Tank Destroyers, but if you get uptiered you're usually at a disadvantage. To compare, the Tortoise has higher alpha, a better rate of fire, and MUCH better gun handling. And better gun depression and traverse angles, better hull armour – you get the gist.
The penetration is also a bit of a handicap. 258 is good enough, but it's not really Tank Destroyer penetration. 315 gold again, it's normally good enough, but it's not what you really expect from a Tank Destroyer. IF you know where to aim, you'll be fine, but you can't just laugh at heavy tank armour like you can with other TDs, you have to know what you're doing.
However, just because it's a little weird doesn't mean it can't work. The gun can work against you, but usually I find it's good enough, especially at close range. You have to abuse the rate of fire as much as you safely can to outmuscle what you fight. I find against heavies this tank works exceptionally, as you usually have the DPM to devour them, and the mobility to circle them too.
Summary is that this tank has effectively a Tier X medium gun with Tier VIII handling (for the alpha it has). It's lethal if you can use the rate of fire, but the handling will hold you back at long range.
The Mobility
This is a very nimble tank destroyer. The traverse speed is extremely uncharacteristic of its class particularly, and it's better even than most mediums at it's tier. 52kph top speed and a good p/w ratio to get it there feel extremely nice, and you can often speed into position much like a medium can. Except of course, your DPM is often much higher than mediums at your tier.
You can relocate extremely easily in this tank, and find flanks quickly and efficiently to put the gun's nice DPM to use. Think faster medium tank kind of mobility – it's around the same as the medium chassis it's based on.
As mentioned earlier, this bodes extremely well against heavy tanks. You can run rings around heavy tanks, and you can do some really funny manoeuvres to outplay them. This tank is not at all vulnerable at close range – the mobility is more than enough to catch tanks that try to circle you if they don't track you.
The Armour
The hull is pretty trash – it'll work against Tier VII tanks, and maybe some Tier VIIIs at range (if they don't fire gold) but everything else can butter it. The real selling point is the casemate armour, which is around 340mm effective armour. This is enough to bounce most top tier gold ammo half the time, which is extremely strong on a tank that's so mobile. However, it's ONLY on the casemate. And that's what you always have to remember in this tank. If you can hide the hull, you are extremely strong. BUT you only have 5.5 degrees of gun depression, meaning you sometimes have to get creative to use it.
On top of this, the K-91-PT is one of the lowest profile tanks at high tier. Most rubble you'd think you can use to get hull down you actually can't because of how low this thing is. You have to know exactly what you can use to hide that hull armour, or at least make it a harder target to hit. If you've played the WZ-120 at Tier IX, you'll know the struggle. At least the mobility makes getting into such positions a bit easier.
The long and short of the armour though – don't rely on the hull. You can rely on the casemate, but only if you know where you can use it.
Everything else
So the K-91-PT has a wonky gun with a good rate of fire, medium tank mobility, and extremely strong armour in one awkward to use place. What else?
Well, the concealment is excellent. Some of the best at high tier, when stationary it's equal to tanks like the Manticore. With a fully pimped crew and equipment, you can get to around 45% camo when stationary and about 29% when moving, which is really nice, especially considering the mobility. This makes relocating even easier, and makes this tank a real threat in the late game, where you can kite heavies that can't see you and get their flanks.
On top of this, the view range is one of the best for a Tier IX tank destroyer at 390m. This would be mediocre for a medium, but for a tank destroyer with this camo value it's very strong. You can often outspot almost anything in the open except for light tanks, which is very valuable when you have near 2800 DPM.
The Summary
I personally find this tank very fun – it's extremely satisfying for me to outplay other whilst in this tank, due to how tricky it is to play. I've had the most success in this tank charging down people who I know have much inferior DPM (some lower tier heavies have like 50% less DPM than you) or by using weird positions where I can only expose the casemate and just chew up anything in front of me. The mobility and stealth make repositioning comfortable, and the view range is extremely good for outplaying opponents in the endgame.
But let me stress this again, THIS IS NOT AN EASY TANK TO PLAY. If you don't like low gun depression, you're going to hate this tank. The lack of turret makes using the gun more tricky, the bad hull armour makes aggressive plays much harder, the bad accuracy makes sniping much more frustrating – the list goes on. If you want an easy tank to play, get one of the other battle pass tanks on offer. This is not a casual tank that you can easily get damage in.
And that's it! If anyone has anything I've missed from playing this tank, feel free to comment, and I'll add it. I hope this helps some of you decide on what tanks to choose from the battle pass
Source: https://www.reddit.com/r/WorldofTanks/comments/n71f30/an_indepth_analysis_of_the_k91pt/