BMP-3 in Russian Army

No bud, I don't buy that.
This thing is simply not needed.

Of course it is needed.

The BMP had a 73mm gun with HEAT and later on HE Frag rounds, but the BMP-2 with its 30mm cannon was found to be more ideal in dealing with enemy helicopters and BMPs... the HE rounds were found to be useful against bunkers and other area targets on the battlefield... they were complimentary... the 30mm and ATGMs for armour and HE for soft and area targets on the ground.

The BMP-3 went a step further with a much better much longer ranged HE round but the 30mm was still adequate with improved AP ammo.

Well now the 30mm is not good enough... in terms of HE it was always marginal which is why the 73mm and 100mm were kept in service (note I am talking about BMP use... for BTRs then 30mm is fine, or even HMG).

The replacement for the 30mm and the 100mm is a 57mm but which one?

The competition was between a new essentially telescopic ammo grenade launcher/APFSDS round launcher 9A94, or the upgraded and improved S-60 anti aircraft gun the 9A91 which uses bottlenecked ammo the same as the ZSU-57-2 and towed S-60, but with a wide range of new ammo types being developed for it.

The advantage of the grenade launcher is much bigger HE bomb and before I knew about the APFSDS round... a lack of AP ammo which meant the S-60 gun round was a shoe in... despite the rounds being much bigger and heavier but with a less powerful HE projectile.

The trump card of the 9A94 gun is its APFSDS round... which will be much more powerful than any APFSDS round you could fit in a 30x165mm calibre shell in terms of length of propellent weight.

You have a low pressure tube that enables to fire projectiles .. let's be optimistic ... with 600-700m/s.

Why do you assume it is a low pressure tube?

The only reason the HE round has such a low velocity is because it is more than 90% projectile with a tiny short propellent stub... if the 125mm HE round only had propellent in the metal stub section its muzzle velocity would probably be lower too.

That is already double the regular pressure, so want to guess how it applies to the bore?

The weapon was designed from the outset to fire High velocity APFSDS rounds... why are you expecting it to struggle with the pressures this round would generate?

And why ...?
If you have w Bulat battery, and long range Kornet on hand?
Why even bother...?

Cost and weight. An APFSDS round is much more compact and cheaper and lighter than either Bulat or Kornet and if the target is within 3-400m and is stationary then why not take the shot with APFDS rounds?

Sure that 57mm rounds are in development, that is what spoils the view.

There are plenty of new rounds in development for both calibres because both calibres are going to be introduced... the 9A91 for the navy and army for air defence roles and 9A94 for BMPs for use against equivalent enemies...

It simply does not adds up. Think about that using your own experience, and turning off the wishful thinking.
No gains, tons of troubles.

No gains?  A very powerful and effective low velocity HE round you can lob out to targets 6km away is amazing, and having a subcalibre high velocity APFSDS round with a bigger heavier longer dart than could be fitted in any 30mm cannon shell case, probably moving at 1.2 to 1.5km per second is the best of every world... in terms of ammo storage and amount of ammo carried and effect on target.

... and you have still shot it with 350-400m/s, or face a massive barrel detonation.

What are you talking about?

The weapon was intended to replace the 30mm cannon in the anti armour and anti soft target roles. For use against soft targets they went for max projectile weight which means it wont be moving very fast through the air at all. That does not matter because when you throw a hand grenade that explodes on impact the speed at which the round arrives means nothing compared to the size of the HE charge that bomb is carrying.
For anti armour use the projectile is tiny and super light weight and the enormous volume of the HE round is removed and replaced with extra propellent with a very light weight low drag projectile.

If you look at the American 20mm cannon for their fighter aircraft it has a small lightweight projectile and it leaves the barrel at over 1.1km/s. That was a choice.

The comparable Soviet round is the 23 x 115mm round that moves at 700m per second from the muzzle. The difference is in the projectile... the Soviet projectile has a heavy HE payload and is intended to do serious damage to anything it hits... the American 20mm is much smaller and relies on multiple hits from a gatling gun to be effective.

If you put the light projectile of the American round in the Soviet round and used a suitable propellent charge you would get a similar very high muzzle velocity.

The point is that the Americans are happy with flat shooting high velocity rounds and the Soviets slower heavier rounds also fired at very high rates of fire.

The Soviet guns wont explode if you put lighter projectiles with more propellent in them... and the American guns wont explode if you put heavier slower projectiles in them either.

Yes, really, because you are using just an opposite example.
You can add a 1/3 of powder to any barrel, but 3x the load to hardly any.
You are a way to smart&old to do that shit without purpose scratch
Are you trying to prove some agenda or something? scratch
I am not interested if so.

You seem to be under the impression that they have taken a low velocity grenade launcher and tried to load high velocity APFSDS ammo in it without any modifications to the design.

We have seen the ground based Grenade launcher, but what we have not seen is the aircraft mounted version for the Il-102 which was twin barrelled and designed to be aimed downwards at targets on the ground in a way to throw the sabots away from the aircraft to limit the chance they would be ingested into the engines. The Il-102 was shown with twin barrel 30mm guns on the centreline but there was a 57mm gun in development... do you think it likely an S-60 be mounted there or the 9A94 with much less recoil for APFSDS and for HE rounds...

Missiles of both Bastion and Arkan modes are loaded separately missles and charges, and by hand. So you can load as fast as a human can handle. The instruction says 6rpm, and that is still perfectly fine.

Manually loaded in the old mount, but with the upgraded system for the BMP-3M the autoloader carried 36 HE rounds and 6 missiles which are all loaded automatically.

Any estimate of loading speed depends on how they are loaded and how far the autoloader has to rotate to get the requested round... less of a problem on the BMP-3 than for a tank with multiple options for each autoloader position.

The old 57mm gun (S-60) had HE and AP rounds but they fired both together so both had to be similar weight and move at similar velocities for the both to hit the same point of aim at any distance. That reduced the AP performance of the old APHE rounds, which was not really very important because aircraft don't carry enough armour to protect from 30mm AP ammo let alone 57mm calibre rounds.

For a BMP role however you need better penetration than an AA gun would require so there are APFSDS rounds for both guns... don't think of them as high velocity and low velocity guns as they both have the capacity to fire high velocity rounds... but the old AA gun should manage better performance in that regard.

In terms of volume:



From right to left we have the 60mm Israeli mini anti tank round, the 57mm 9A91/S-60 round, then an old 40mm Bofors round, and then a new western 50mm round developed from a 35mm round but necked out to take a larger calibre projectile, then the 35 x 228mm round the 50mm round is based on and finally a 40mm telescoped round.

The 50mm round is obviously 7mm narrower than the 57mm 9A94 round but otherwise they look very very similar and as you can see would take up rather less space than the 57mm rounds that the 2S38 will be using as an air defence weapon.

Perhaps you might want some further reading... try:

https://www.russiadefence.net/t4074p600-kurganets-boomerang-discussions-thread-2

Can I suggest you start reading from post 606 and specifically focus on the posts by Mindstorm.

Edit... BTW the 100mm gun of the BMP-3 was designed specifically for low pressure 4km range HE rounds and missiles... when they developed new ammo they found the gun and the turret had problems because the gun was not mounted in the centre so the offset recoil cracked the turret rings... with redesign and improved barrels they can now use higher pressure ammo just fine.

Now if they display APFSDS ammo with the gun as well as HE rounds as being the standard ammo why would you have problems accepting it might go into service using both?

I doubt they have started mass producing the weapons yet...

ALAMO wrote:

And this is a part I don't buy.
Don't belive the high velocity of this gun.
As easy as that.

Note that hypervelocity performance is not a strict requirement for subcaliber projectiles to penetrate through the thin armor of current and incoming NATO IFVs. That's only really necessary for tank main guns because the typical LOS thickness of target armor is close to the length of the subcaliber projectile itself and only when impacting at hypervelocity speeds would the projectile have the energy to displace more armor material faster than it is eroded (and therefore defeated). With minor exceptions, most target IFVs would have a protection rating that is barely above stanag level 6 - so 30 mm APFSDS and the like, which is easily outclassed by the more massive 57 mm APFSDS. Even if the latter is a lot slower, it simply wouldn't matter since the armor would have far more projectile to defeat than it was designed for.


As for the Bulats, its presence within the Kurganets loadout is really simple to explain. While the APFSDS might suffice for combat ranges from 0 to 2 km, it probably would not have as much energy to punch through the same IFV targets at 3 - 5 km. You can't really ignore these targets either because they have ATGMs that can kill MBTs at any range they hit. You can make use of your own heavy ATGMs but since they are so few and grossly overkill for IFVs its not really a good trade. So that leaves the Bulat mini-ATGMs as the only other option to take care of lightly armored targets that are beyond the effective range of the APFSDS.

And that is exactly my point. I suppose we will see different guns in different modifications.

Enemy armour has changed... when the BMP first came out the 73mm gun was to use against tanks and armour within 500m where the ATGM could not be gathered in time for reliable hits... when it first entered service it had two buttons for the 73mm gun... HE and HEAT... but not HE was available till much later.

When the BMP-2 entered service the newer ATGMs solved the short range engagement issues against tanks so the 30mm cannon was for AP and HE use, but by then the BMP had its HE shells which were rather more effective than the 30mm HE shells against some targets so they kept both in service.

When it came time to introduce the BMP-3 the 30mm cannon was becoming a bit marginal and the HE performance was upgraded... it was no accident that there was no HEAT 100mm round except for the missiles.

In this day an age however the 30mm is not powerful enough against enemy BMPs let alone tanks so they are going to 57mm and it is pretty clear the 57mm 9A94 has won the competition for the BMP-3 upgrade to the B-19. The turret with the high velocity 9A91 for the BMP-3 tests was the B-17 with the Dagger turret and they chose the B-19.

Because it is how the producer describes it. Using both "low pressure" and "low ballistic" terms.

The HE round is a low pressure round... there is no value in a high pressure HE round for anything except AA use.

The 2S38 uses the high velocity 57mm gun because that is useful for air defence... hell... for all we know they might introduce a towed 57mm high velocity gun for air defence and ground support in static and mobile roles.

Yes, that is a valid point, but I would bet that what we see as APDS here, is merely a try to get a 30mm level of armor piercing.

That does not make sense... you go for a bigger calibre in APDS to get better penetration... not to keep it the same.

If 30mm penetration levels were OK then they could just keep the existing arrangement with the 100mm and the 30mm guns for the BMP... in fact they could hang the Kornets on the outside (being 152mm calibre weapons) but the Bulat missiles should be able to fit down the 100mm gun tube with a sabot shoe to get a gas seal.

And this is a part I don't buy.
Don't belive the high velocity of this gun.
As easy as that.

Why is it so hard?

The Steyr entry for that American competition for a new super assault rifle used a 5.56mm sized cartridge but it had a very light flechette round projectile instead of a much heavier bullet... it was like 1-2 grammes compared with about 5-6 grammes for a normal bullet... the rifle had iron sights that were fixed to 800m because there was no bullet drop to that range. It just wasn't particularly accurate... and recoil was almost zero.

Converting existing rounds to high velocity small calibre darts is easier and much more common than you seem to think... the very light weight projectiles greatly reduce felt recoil and are accelerated down the barrel much more rapidly than full calibre rounds.

A typo. I meant deterioration.

Plastic driving bands should reduce that as a problem... they are already using those for their aircraft cannon to extend their useful life by a couple of times.

Because this is what the producer states. Who am I to argue with them?

The producer of the grenade launcher pitching it as a grenade launcher for infantry use.

They are talking about a new replacement MANPAD missile for Verba... for quite some time even Verba was not mentioned and now they are talking about its replacement...

What are they not talking about and why?

Note that hypervelocity performance is not a strict requirement for subcaliber projectiles to penetrate through the thin armor of current and incoming NATO IFVs.

Indeed the simple fact that the penetrator could be much longer and therefore concentrate more weight at the point of impact means it will have good penetration even if it is not faster.

As for the Bulats, its presence within the Kurganets loadout is really simple to explain. While the APFSDS might suffice for combat ranges from 0 to 2 km, it probably would not have as much energy to punch through the same IFV targets at 3 - 5 km. You can't really ignore these targets either because they have ATGMs that can kill MBTs at any range they hit. You can make use of your own heavy ATGMs but since they are so few and grossly overkill for IFVs its not really a good trade. So that leaves the Bulat mini-ATGMs as the only other option to take care of lightly armored targets that are beyond the effective range of the APFSDS.

You also have to be aware of the fact that APFSDS rounds in a 57mm grenade launcher is different from that of a tank round in that you could probably direct a burst of 3-4 rounds at a BMP target so the chances of hitting a soft spot and doing real damage are increased... for which you don't have to stop to fire...

The real irony is that the round in this picture that looks most like the 57mm grenade round is the 40mm telescope round which we know has a large HE projectile with a small propellent load... like a grenade launcher... and also a sabot round with a high velocity dart and the rest of the case filled with propellent to get max possible velocity...

And the 57mm grenade round is bigger than the 50mm US round in this picture:




So for clarity, from the left, the 40mm telescope round, the 35mm cannon round popular in the west, a 50mm necked out shell based on the 35mm case which is essentially similar to the 57mm grenade except about 1cm narrower in calibre, then we have to old 40mm bofors calibre, and then the Russian High velocity 9A91 gun round and lastly the Israeli 60mm round for use as a light anti tank round for tank killing vehicles (older T-55/62 early 72 models and Chinese and western vehicles of a similar generation mostly).

ALAMO wrote:Yes, that is a valid point, but I would bet that what we see as APDS here, is merely a try to get a 30mm level of armor piercing.

Alamo i understand what you think ,but i have the sensation that you do not perfectly understand the difference in mass between a 57 mm round and a 30 mm one and the huge difference in muzzle energy delivered.

https://quarryhs.co.uk/CANNON2.pdf


Even with a reduced muzzle velocity (let put in the 750-800 m/s at the barrel bore) a modern 57 mm APFSDS rod will literally pass from the front to the rear the armor of practically any foreign IFV operative today at tactically relevant ranges (may be with the exception of some parts of frontal projection of Puma IFV in the most heavier armoured version at 2000 m of disrance and over).

The gun which we are talking about here is indeed a reduced ballistic one , the reason is to: 1) allow a greater volume's fraction of explosive to be included in the explosive/fragmentation rounds ,that represent obviously the main round used by IFVs 2) allow a greater number of rounds to be carried without the necessity to occupy the internal space of the infantry squad 3) reduce weight and complexity of the feeding mechanism reducing logistical burdens.

The point to include an APFSDS -3БМ76- among the rounds available for the 2A94 gun is that even if an enemy moving IFV would in some way survive to the attacks at large stand-off ranges carried on with guided missiles , it could be successfully engaged with a salvo of 7-8 rounds at distances greater than the maximum of theirs 30-35 mm guns with a very high probability of destruction.

The computations of hit possibility of a moving enemy IFV at 2000-2500 m with a similar salvo give, as result, that at least one round ,and often two, would hit directly the enemy IFV's chassis in spite of the reduced muzzle velocity .

the american 50mm is seemingly a modified 25mm, while the LSHO is an all new gun that is around the same size as the 2a42. It would therefore be reasonable enough to guess that it may well be quite a bit more powerful than the american 50mm.

The-thing-next-door wrote:the american 50mm is seemingly a modified 25mm, while the LSHO is an all new gun that is around the same size as the 2a42. It would therefore be reasonable enough to guess that it may well be quite a bit more powerful than the american 50mm.

The "50mm" round of the future american authomatic gun use the chase of the 35 mm round.

From 1:34

ALAMO wrote:While you are saying "greater fraction of explosives" that applies perfectly well to any different than APDS round.
That does not add up.

ALAMO the point is that just reducing the overall gun pressure allow you to employ a greater number of HE/HE-Frag/incendiary rounds with a greater fraction of filling explosive material and moreover those rounds can follow a more arched trajectory increasing, in this way, sharply the efficiency against enemy infantry in defilade and entrenched ATGM and machine gun squads.

This allow the infantry squads transported by a group of Курганец-25 in IFV configuration to gain a crushing superiority over the enemy one and this is the primary mission of an IFV.

Obviously on the other side a similar gun will explot only a fraction of the ballistic potential of the 57mm caliber ; to be clear in a pure gun versus gun duel a Курганец-25 will decisively lose against a 2С38 Деривация-ПВО because the latter could engage the former from a significantly greater range with greater P-hit and penetration chance.

At the same time an IFV armed with an high ballistic 57 mm gun, like that of a 2С38, would be vastly inferior in execute and support combined arms infantry/mechanized missions both on the offense and on the defence.

As I said, this might be my own fetish that if you can have a 57mm cannon capable of punching 200+mm, why stay relaxed having something doing half of that, only because it is just good enough.
Unreasonable Laughing but all mine! Very Happy

But they will have both guns, so if they needed better penetration and higher muzzle velocity they could simply swap turrets.

At the start of WWII the Soviets had to make a choice... what gun to put on their T-34... they had a 76.2mm gun that didn't have great penetration, but the HE round was very effective. They also had a new 57mm gun whose penetration was very very good, but its HE round was on the small side and the AP materials were expensive and not in full production... they already had munitions factories making 76.2mm rounds.

They chose the 76.2mm gun because it had a much better HE round so for most targets it was better than the 57mm and for armoured targets of the time it was good enough.

When it came time to up arm the T-34 they could still have gone with a 57mm gun... it was in production and could have done the job, but the 85mm gun had a much better HE round making it a better round on a battlefield where there were only a few thousand tanks that needed such penetration to deal with.

When it came to heavy tanks they made the same decision... they went for 122mm guns instead of the better performance 100mm guns because the HE rounds were better and it was already in production.

In this case, there is an APFSDS round for the 57mm grenade launcher, but the HE round for the 57mm grenade launcher is far bigger but also far slower than the HE round for the high velocity 57mm gun... but muzzle velocity is irrelevant and is actually a problem for shooting over cover.

A BMP-2M has a 30mm high velocity cannon, but also has a 30mm grenade launcher because the 30mm grenades are essentially a projectile with a tiny propellent charge that can lob bombs over front cover at targets that would be impossible to hit with the high velocity flat shooting 30mm cannon rounds.

They compliment each other and are different enough for it to make sense to have both.

In the case of these two 57mm rounds for infantry support against ground targets the grenade launcher is excellent... 6km range... huge HE bomb... command detonated with radio command system... and an APFSDS round for anti armour use for harder targets. With the high velocity rounds the range is probably 12-14km and the higher velocity makes engaging aircraft much easier and more efficient... air burst HE rounds and even guided rounds would be excellent for shooting down drone targets... guided rounds for manouvering targets you could otherwise waste hundreds of shots trying to hit.

I think this is a win win situation... and more so because an APFSDS round is a very fast very low drag round that generally shoots pretty straight so against a hovering helicopter... even if it is hovering behind a building or a tree could possibly be engaged with APFSDS rounds because the round should be able to deal with several centimetres of armour and retain energy so for a helicopter it could do some serious damage having a few of those being fired in its direction...

What is really exciting is the new BMPT designs.

Traditionally the BMPT was a fire power vehicle to over whelm ground targets with fire power to allow tanks to operate without infantry support... they originally used gun based air defence vehicles including BTR-40s with twin 14.5mm HMGs, and then BTR-152s with twin 23mm cannon and then ZSU-57-2s and Shilkas and then Tunguska... but pretty soon they realised the thin armour limited their ability to operate near the front line so they developed the BMPT but they went conservative and went for two 2A42 30mm cannon and two hull mounted 30mm grenade launchers and a top mounted rifle calibre machine gun plus four ATAKA missiles.

I always thought the twin barrel 30mm cannon of the Hind would offer much more devastating fire power in terms of rate of fire (3,500rpm), but also that the twin 23mm cannon used in the current model Hinds in a chin turret used a 23mm round with a heavy HE projectile but in compact 23 x 115mm rounds similar in size to a HMG round so lots of ammo and low recoil, but high fire rate and devastating fire power with all those HE rounds landing together...

The core problem I saw was that it could only hit four precision targets at more than the 4km range of the 30mm cannon with its missiles, so I was thinking taking the BMP-3 design and replacing the single barrel 30mm 2A72 gun with the twin barrel either 30mm or 23mm gun, so you had 36 good solid HE rounds and 6 missiles out to 7km which is plenty... but now with this 57mm grenade launcher that can also penetrate light armour I would say a 57mm grenade launcher together with the twin 23mm cannon from the Hind would provide devastating fire power, with a 40mm grenade launcher attached to the rear of the turret... the radio command detonated 57mm HE shells could be complimented with 40mm radio command detonated grenades that are designed with rear mounted HE charge and front mounted fragments like a small claymore mine for use in shooting down enemy drones... it would be like a super shotgun round that can be set off close to the drone.... it could also be used against enemy troops in the open and a range of other targets... you could even set it to explode on impact blasting the fragments into the target like a shotgun door entry gun...

Having three calibres of ammo (plus rifle calibre machine guns of course) means you could carry enormous loads of ammo... out to 2.5km a 40mm grenade launcher is going to be vastly more effective than any rifle calibre weapon or even HMG calibre weapon... there is a reason cannon are so devastating and that is shell fragments and explosives introduce enormous numbers of lethal projectiles on or around the point of impact... something a rifle bullet does not do.

And we never got the answer if 30mm UBR-11 APFSDS rounds are in service now....

Mindstorm wrote:

ALAMO wrote:Yes, that is a valid point, but I would bet that what we see as APDS here, is merely a try to get a 30mm level of armor piercing.

Alamo i understand what you think ,but i have the sensation that you do not perfectly understand the difference in mass between a 57 mm round and a 30 mm one and the huge difference in muzzle energy delivered.

https://quarryhs.co.uk/CANNON2.pdf


Even with a reduced muzzle velocity (let put in the 750-800 m/s at the barrel bore) a modern 57 mm APFSDS rod will literally pass from the front to the rear the armor of practically any foreign IFV operative today at tactically relevant ranges (may be with the exception of some parts of frontal projection of Puma IFV in the most heavier armoured version at 2000 m of disrance and over).

The gun which we are talking about here is indeed a reduced ballistic one , the reason is to: 1) allow a greater volume's fraction of explosive to be included in the explosive/fragmentation rounds ,that represent obviously the main round used by IFVs  2) allow a greater number of rounds to be carried without the necessity to occupy the internal space of the infantry squad  3) reduce weight and complexity of the feeding mechanism reducing logistical burdens.

The point to include an APFSDS -3БМ76- among the rounds available for the 2A94 gun is that even if an enemy moving IFV would in some way survive to the attacks at large stand-off ranges carried on with guided missiles , it could be successfully engaged with a salvo of 7-8 rounds at distances greater than the maximum of theirs 30-35 mm guns with a very high probability of destruction.

The computations of hit possibility of a moving enemy IFV at 2000-2500 m with a similar salvo give, as result, that at least one round ,and often two, would hit directly the enemy IFV's chassis in spite of the reduced muzzle velocity .

If low velocity APFSDS was so good, why was the concept never implemented during the cold war? The technology existed.

You were (over)-generalizing what I've said without context. That being I'm talking about HE against lightly armored targets, note the limiter.

I was talking about modern IFVs and wheeled tank destroyers that are too heavily armored against HE overpressure and fragments, but also too far away to be accurately hit by a low velocity gun, but also not protected against APFSDS 30mm rounds. Using ATGMs at 1-2km is a waste when autocannons with APDS/APFSDS can be used at that range.

You're not making sense. The rate of fire matters not, only the ammunition capacity does. IFVs are firepower support: you're not supporting anything if you've blown your load in 30 seconds of firing, and have to return to base to rearm.

Most AFVs both with cannons and autocannons today have pitifully low ammo counts in their ready racks/carousels. The leclerc has less than 20 rounds in its ready rack. T-72/90/80 have 22 rounds in their carousels. That means less than 20 HE rounds and less than 10 APFSDS rounds before there needs to be a lengthy process of restocking that is unfeasible in the heat of combat. Nobody has complained about their ability to support troops, even though sustained fire will deplete the carousel of one type of round in around 20-50s.

The BMP-2 has 500 rounds total and a RoF of 550rpm. That will the deplete the ammo in less than a minute, yet nobody thinks that was a problem. The Shilka, which was prized for its fire support capability, depletes all of its ammo in 20-30s sustained fire. Only you think thats a problem. Also there are no sustained engagements in peer to peer warfare that warrant sustained 20s+ fire from an AFV.

That's pitifully low that you would have to exercise as much fire restraint as the tanks themselves, only theirs have actual weight of fire behind them.

How is it pitifully low? Notice that I never said automatic fire(80+rpm) is needed. 40-50rpm is plenty and its not automatic fire. If a T-15 has a 76mm/85mm gun with 40-60 rounds and 20-50rpm it will deplete its ammo rack in 120-50s which is more than enough.

That's why nobody bought the thing, not even the Italians. Right. The Derivatsiya is just a revamped S-60, which predates the Otomatic. It even uses some of the old rounds developed for the S-60.

Only because the italians were broke and aircraft had priority for NATO over AA pieces. The OTOMATIC was ahead of its time. If it was designed today, in the era of cheap drones and obsession with programmable airburst ammo, it wouldve sold like hotcakes.

The S-60 was a towed AA gun. It has nothing to do with derivatsiya. If youre talking about the ZSU-57, the only thing in common is that theyre both tracked and have 57mm guns.

They also store that ammo alongside the crew. If you seperate the ammo and flammables from the crew you'd find you don't have much space for ammo at all.

I highly doubt that. With telescoped ammo, it wouldnt be a problem at all.

limb wrote:
I was talking about modern IFVs and wheeled tank destroyers that are too heavily armored against HE overpressure and fragments, but also too far away to be accurately hit by a low velocity gun, but also not protected against APFSDS 30mm rounds.  Using ATGMs at 1-2km  is a waste when autocannons with APDS/APFSDS can be used at that range.

There are no IFVs, or cantaloupes for that matter that can withstand a 100 mm HE hit but not 30 mm APFSDS. Not a single one.

limb wrote:
Most AFVs both with cannons and autocannons today have pitifully low ammo counts in their ready racks/carousels. The leclerc has less than 20 rounds in its ready rack. T-72/90/80 have 22 rounds in their carousels. That means less than 20 HE rounds and less than 10 APFSDS rounds before there needs to be a lengthy process of restocking that is unfeasible in the heat of combat. Nobody has complained about their ability to support troops, even though sustained fire will deplete the carousel of one type of round in around 20-50s.

That's because MBTs only service choice targets of a higher threat level (i.e. anything that can take them out) with their main gun. IFVs, on the other hand have little choice but to shoot at any and all threats to itself and its dismounts seeing as they lack the armor to resist heavy enemy fire without rapidly turning into burning hulks.

limb wrote:
The BMP-2 has 500 rounds total and a RoF of 550rpm. That will the deplete the ammo in less than a minute, yet nobody thinks that was a problem. The Shilka, which was prized for its fire support capability, depletes all of its ammo in 20-30s sustained fire. Only you think thats a problem. Also there are no sustained engagements in peer to peer warfare that warrant sustained 20s+ fire from an AFV.

The main advantage of the autocannon is the the flexibility to tailor its round output per target - a machinegun position might require a single burst of 2-3 rounds of 30 mm to demolish while an IFV could eat a couple longer bursts. The larger the calibre though, the less control you have. Suddenly instead of "killing" 250 machinegun positions with the 30 mm, you can only "kill" 50 with a 76 mm. Obviously too small a calibre and you might not be able to kill the targets at the higher end of the spectrum. A good autocannon straddles the compromise between the two requirements to achieve as much stowed kills as possible while still remaining viable against light armor.

limb wrote:
How is it pitifully low? Notice that I never said automatic fire(80+rpm) is  needed. 40-50rpm is plenty and its not automatic fire. If a T-15 has a 76mm/85mm gun with 40-60 rounds and 20-50rpm it will deplete its ammo rack in  120-50s which is more than enough.

Its not about how long you can keep shooting, its how many targets you can fire upon.

limb wrote:
Only because the italians were broke and  aircraft had priority for NATO over AA pieces.  The OTOMATIC was ahead of its time. If it was designed today, in the era of cheap drones and obsession with programmable airburst ammo, it wouldve sold like hotcakes.

The 76 mm calibre is currently in use for naval applications - there's nothing stopping people from adopting it for AFVs.

limb wrote:
The S-60 was a towed AA gun. It has nothing to do with derivatsiya. If youre talking about the ZSU-57, the only thing in common is that theyre both tracked and have 57mm guns.

We were talking about the calibre itself, not just some implementation.

I highly doubt that.  With telescoped ammo, it wouldnt be a problem at all.

So now you need telescoped ammo. Why not ask for californium nuke tips as well if we're going to ignore the feasibility of using existing systems in favor of pie in the sky implementations.

Not only those two, 2A70/2A42/2A72 is not going anywhere, anytime soon. Accepted with the newest models they have in the pipeline.

Except that the 2A70 is a BMP-3 gun mount and with the B-19, they are phasing the 2A70 out for the 2A94 it seems... presumably as they get upgrades the turrets will be replaced over time.

The 2A42 will remain in helicopter mounts of course and plenty of vehicles with small 30mm cannon turret mounts will continue to use 2A42 and 2A72 because they are useful weapons for a range of roles... especially with radio command air burst shells which will also be very useful for 2A38M cannon on Tunguska and Pantsir...

Does the 2A70 have a future.... perhaps a super APFSDS round could be developed for it... the length would allow quite a decent length penetrator to be loaded and a longer barrel and heavier higher pressure barrel might make it a useful alternative for upgrading older gen tanks in the third world... something you could fit into a T-55 or T-62 that could be effective against similar generation enemy vehicles but with a decent HE round and missiles of course... a tank diameter autoloader should allow 60-70 rounds to be carried in an autoloader ready to fire... increased pressure could allow a 10km range for HE shells moving a bit faster perhaps... certainly the company that makes the gun could consider that effectively turning it into a Russian equivalent to the Israeli 60mm APFDS round but with a much more capable HE round.

That starts to be a logistic mess, to be honest, but I suppose they will optimize the location of those units somehow.

They have managed to eliminate the 100mm rifled tank guns, though they still use 100mm smoothbore towed MT-12 gun mounts as a sort of super SPG-9, and the 115mm smoothbore is gone from the inventory too, though it sounds like they have had a rethink regarding replacing the 122mm with 120mm gun/mortar with the Hosta gun/mortar on the 2S1 artillery vehicle mount.

The real progress is in the vehicle families which will be a radical shakeup of the multitude of vehicle types they need to operate.

With previous vehicle families there were radical changes to increase protection or engine performance or weapons, but the new vehicle families are designed to have growth potential in armour and engine power and of course modular weapons options too.

And we never got the answer if 30mm UBR-11 APFSDS rounds are in service now....

I would be more interested in these radio command detonated rounds... they are using radio command for the 57mm rounds because of the fact that lasers might not reach too far in the rain or snow or dust or fog, so the radio command detonation options are more likely to have effect in bad weather or smoky conditions that would make lasers less effective... it would also be better at sea as well with sea mists and sea spray probably blocking lasers better than radio command signals.

I would assume the same would apply to the 30mm and also even the 125mm ANIET system if they are going to have a unified system... they could have billions of unique radio command combinations so the enemy could not anticipate the correct signal to render them ineffective... each individual round could be coded uniquely as it is fired so a burst from a 2A38M cannon could be signalled so that the rounds explode all around the target damaging it from all angles.

Can't see the Russian Army needing an APFSDS 30mm cannon shell urgently any time soon, but adding it to the inventory would be useful... imagine how useful it would be on a Havoc on one ammo magazine and HE air burst ammo in the other...

If low velocity APFSDS was so good, why was the concept never implemented during the cold war? The technology existed.

Technically low velocity AP was exactly what the T-34 was armed with and at the time it was just fine.

They could have fitted a much more powerful gun that was bigger and heavier and made the vehicle slower and more expensive to make, but for the first few years of the war the T-34/76 was just right.... and that is the key... good armour, excellent mobility, reasonable gun for the time... it wasn't amazing at anything, but it was easy to mass produce and it was cheap and simple which was its most important feature.

The AP round for the T-34 was only about 600m/s, but it was good enough for the targets it was going up against at the time.

I was talking about modern IFVs and wheeled tank destroyers that are too heavily armored against HE overpressure and fragments, but also too far away to be accurately hit by a low velocity gun, but also not protected against APFSDS 30mm rounds. Using ATGMs at 1-2km is a waste when autocannons with APDS/APFSDS can be used at that range.

I agree, you are right, but how many thousands of such enemy vehicles are you expecting the Russians to come up against right now?

Most AFVs both with cannons and autocannons today have pitifully low ammo counts in their ready racks/carousels. The leclerc has less than 20 rounds in its ready rack. T-72/90/80 have 22 rounds in their carousels. That means less than 20 HE rounds and less than 10 APFSDS rounds before there needs to be a lengthy process of restocking that is unfeasible in the heat of combat. Nobody has complained about their ability to support troops, even though sustained fire will deplete the carousel of one type of round in around 20-50s.

I think you are over estimating the role of vehicle mounted guns in modern combat, most of the time they will be delivering and supporting mounted infantry and taking the odd potshot missile launch at any enemy vehicles that appear. The Kornet and Bulat are very cheap laser beam riding missiles they could order in enormous numbers and still not break their bank.

I would say an AFV with 12 ATGMs... all ready to fire and including 8 under armour and protected from enemy fire and a 57mm main gun is pretty damn well armed compared with any competition... especially considering they likely have the communications capability to call in helicopter support and artillery support providing those forces directly with accurate target data... and it is not just tanks and BMPs in Russian armoured forces... they will also have mortar carriers, and organic artillery support including rocket artillery as well as ATGM vehicles in an Infantry division... lack of fire power really isn't going to be one of their problems.

Only you think thats a problem. Also there are no sustained engagements in peer to peer warfare that warrant sustained 20s+ fire from an AFV.

Except that when engaging soft or area targets then HE rounds will be used much more often than AP... which in many situations might not be used at all... which is why the 73mm gun of the BMP led to the 100mm gun of the BMP-3 and was not just a dead end.

The selection of the 57mm grenade launcher was mainly because the big HE bomb is more useful most of the time than the APDSDS would be, though of course they will carry both... perhaps a 20-30mm subcalibre APHE round with perhaps a 1kg HE payload with fragments that could be developed for penetrating light cover to destroy things like buildings where it penetrates into a room rather than just exploding on the outside... Extra propellent leading to a higher flight speed of perhaps 700-800m/s or something to flatten out the trajectory and give it some soft target penetration performance... against buildings or bunkers.

How is it pitifully low? Notice that I never said automatic fire(80+rpm) is needed. 40-50rpm is plenty and its not automatic fire. If a T-15 has a 76mm/85mm gun with 40-60 rounds and 20-50rpm it will deplete its ammo rack in 120-50s which is more than enough.

What on earth are you expecting to fire at that would need that sort of fire power.... maybe if you want to sink a ship... but most BMPs could be taken out with one or two 85mm rounds so the rest of the rate of fire is pointless.

Only because the italians were broke and aircraft had priority for NATO over AA pieces. The OTOMATIC was ahead of its time. If it was designed today, in the era of cheap drones and obsession with programmable airburst ammo, it wouldve sold like hotcakes.

Its calibre is probably too big for most drones... it was certainly a clever idea but it was invented on the wrong side of the iron curtain to have any future... HATO are air power focused and likely will never take on an enemy with air power strong enough to actually need air defence vehicles.... if they have any say... and as they start wars... they normally get the entire say.

The S-60 was a towed AA gun. It has nothing to do with derivatsiya. If youre talking about the ZSU-57, the only thing in common is that theyre both tracked and have 57mm guns.

2S38 only makes sense with airburst and guided 57mm cannon shells, while the conventional HE rounds will be very interesting, and the APFSDS rounds impressive I don't think they will be used very much on land or at sea.

It is optimised to penetrate rather more armour than any aircraft could possibly be fitted with... unless airships become popular again in which case an APFSDS that goes in one side and out the other would be more effective than a round that explodes on the skin and might pop two or three hydrogen bags at the point of impact.

Its not about how long you can keep shooting, its how many targets you can fire upon.

It is also about supporting your dismounted troops and providing effective fire support and transport.

The 76 mm calibre is currently in use for naval applications - there's nothing stopping people from adopting it for AFVs.

Except the fact that most naval artillery uses two to three decks for ammo handling and loading and fusing... which is not really an option for most land based vehicles... but the concept is the same.

Also water absorbs recoil in a way that land based vehicles don't.

So now you need telescoped ammo.

The Russian 57mm 9A94 grenade launcher effectively impliments the telescoped ammo concept even if it is not exactly coke can shaped.

limb wrote:If low velocity APFSDS was so good, why was the concept never implemented during the cold war? The technology existed.

limb there is nothing inherently good in lower velocity APFSDS , the factor leading to the implementation of APFSDS in a reduced ballistic authomatic gun is that for the first time in the post WWII history such a round could anyway penetrate without any problem the armor of most advanced enemy counterpart vehicles ; this is the product of the success in engineering a remotely controled turrett with a gun of very big caliber -57 mm- for an IFV.

In substance the primary role of a Курганец-25 in IFV configuration will remain to support of its carried infantry squad of 8 operatives - that ,by Курганец-25 wide introduction in service, will be likely fully fitted with "Сотник" suit and will have theirs surveillance/tactical UAVs, squad ATGMs, support authomatic weapon and/or MANPADS - and here ,as explained a reduced ballistic 57 mm gun offer a significantly greater potential in comparison with a high ballistic one.

This same IFV Курганец-25 will be capable to shot 7-8 APFSDS (even if at muzzle speed of 700-800 m/s) and almost surely hit and destroy any moving enemy OTAN's IFV (including the models now in selection for theirs modernization and future programs , except maybe one).

This was impossible to realize with 30 mm rounds ,because reduced velecity rounds in this caliber ,while surely capable to hit an enemy IFV at tactically relevant range if used in salvo of the necessary density ,would be absolutely incapable to penetrate a latest Bradley, Warrior or Marder or worse CV-90 or Puma .

The whole concept behind telescoped ammo is that the components for a HE round and an armour piercing round are opposites... a HE round benefits from more HE, so the heavier the bomb generally the more effective it is on target. It does need some propellent to get it to the target but the focus is HE projectile weight.

With an AP however it comes down to a lot of different factors and for the best penetration an narrow penetrator that is strong enough to not just bend and collapse that is long enough to concentrate a lot of weight on the penetrating point and made of hard enough material that will penetrate armour but not so hard it shatters on impact.

The HE round all the weight and volume of the entire round 90% for the projectile and 10% for propellent... for APFSDS rounds 10% is a narrow arrow shaped dart as long as you can make it and with 90% the sabot holding the penetrator in place down the barrel and of course propellent to make it go as fast as possible.

The design is always a compromise based on what you want to penetrate... you could have a tiny 1 gramme penetrator that will all that case volume and all that propellent in a 57mm round would be travelling at enormous unheard of speeds, but super light projectiles can be accelerated quickly in even a short barrel but its light weight means it does not push the air in front of it aside efficiently so it accelerates to the highest speeds but it also slows down the fastest so it might only travel 300m before it drops to the ground.

Heavier projectiles means they retain speed better and penetrate armour better when they hit stuff... the material it is made of and how long it is are two easy ways to make a penetrator heavier, but if the penetrator is too heavy it wont accelerate to a very high speed.

You see it with cannon shells and bullet... very light weight bullets like the 223 and 5.45 might create fearsome wounds at short range when they are moving fast, but the Americans cancelled a 5.56mm calibre gatling gun because it was useless at 800m or more, but was heavy and expensive so they just use 7,62 calibre miniguns and 12.7mm calibre miniguns because the extra weight and cost is worth it.

Take a 7kg 125mm APFSDS round currently used on a T series Russian tank... to get extra velocity they could make it a 5 kg round by making it thinner or shorter, but making it longer means extra weight but without extra drag so it greatly adds to penetration to actually have slightly more weight than more velocity in that case.

If you want a higher velocity round just make the penetrator lighter, but you should make the penetrator as long a the case allows because that is extra mass without a lot of extra drag like you would get if you got extra mass by making it thicker.

Down the track there will be potential for growth too simply with improved propellants and new penetrator metal alloys and shapes to reduce drag.

The clever design applied to the 57mm 9A94 grenade launcher could just as easily be applied to the 100mm rifled 2A70 cannon but its best feature was compact ammo and decently powerful HE... they didn't need or want a HVAPFSDS round...

There are no IFVs, or cantaloupes for that matter that can withstand a 100 mm HE hit but not 30 mm APFSDS. Not a single one.

What is your proof?

The main advantage of the autocannon is the the flexibility to tailor its round output per target - a machinegun position might require a single burst of 2-3 rounds of 30 mm to demolish while an IFV could eat a couple longer bursts. The larger the calibre though, the less control you have. Suddenly instead of "killing" 250 machinegun positions with the 30 mm, you can only "kill" 50 with a 76 mm. Obviously too small a calibre and you might not be able to kill the targets at the higher end of the spectrum. A good autocannon straddles the compromise between the two requirements to achieve as much stowed kills as possible while still remaining viable against light armor.

You're assigning an arbitrary amount of ammunition to to kill arbitrary targets. machine gun positions arent the only things IFVs encounter and they could be easier or harder to kill. Some targets might require 2-3 shells, other 40-50 shells, others the entire belt. A 76mm airburst shell will be far more effective and quick at destroying any entrenched position at 2-3km compared to a 30mm cannon, due to far superior accuracy. Also the ability to accurately destroy tanks and IFVs and having more accuracy and faster shell speeds than an ATGM would makes a 76mm gun worth it compared to a 30mm autocannon paired with a 300m/s howitzer.
Also modern western IFVs are immune to 30mm AP-T shells, so your claim of needing "a couple of longer burts" is just your wishful assumption.

That's because MBTs only service choice targets of a higher threat level (i.e. anything that can take them out) with their main gun. IFVs, on the other hand have little choice but to shoot at any and all threats to itself and its dismounts seeing as they lack the armor to resist heavy enemy fire without rapidly turning into burning hulks.

BS, MBTs, like IFVs are are there to support infantry, which means shooting at anything that can kill infantry. The way you claim MBTs choose targets is US doctrine, where tanks are expected only to destroy other tanks and vehicles.

Its not about how long you can keep shooting, its how many targets you can fire upon.

How many is arbitrary.

So now you need telescoped ammo. Why not ask for californium nuke tips as well if we're going to ignore the feasibility of using existing systems in favor of pie in the sky implementations.

And now your utter ignorance is showing. Telescoped ammo is a very old technology from the early 70s and telescoped 40mm ammo is in service in the british warrior ajax IFV. Its a mature technology, more mature than 57mm 700-800m/s APFSDS shooting grenade launchers. Autoloading mechanisms for telescoped ammo are also more mechanically simple.

limb wrote:
What is your proof?

Its a bigger shell with a bigger bang - how is it not obvious?

limb wrote:
You're assigning an arbitrary amount of ammunition to to kill arbitrary targets. machine gun positions arent the only things IFVs encounter and they could be easier or harder to kill. Some targets might require 2-3 shells, other 40-50 shells, others the entire belt. A 76mm airburst shell will be far more effective and quick at destroying any entrenched position at 2-3km compared to a 30mm cannon, due to far superior accuracy.  Also the ability to accurately destroy tanks and IFVs and having more accuracy and faster shell speeds than an ATGM would  makes a 76mm gun worth it compared to a 30mm autocannon paired with a 300m/s howitzer.

Its far more effective at killing harder targets, yes. But what about suppression?

limb wrote:
Also modern western IFVs are immune to 30mm AP-T shells, so your claim of needing "a couple of longer burts" is just your wishful assumption.

Only the most modern western IFVs are reliably protected against even 30 mm AP shells. Stuff like the Puma and the Lynx which are about as expensive as a tank - and yet they aren't immune to the ATGM.

limb wrote:
BS, MBTs, like IFVs are are there to support infantry, which means shooting at anything that can kill infantry. The way you claim MBTs choose targets is US doctrine, where tanks are expected only to destroy other tanks and vehicles.

They aren't that myopic, since each tank still carrier a large complement of HE-frag shells. Still, there's only so much targets you can shoot with just 40 shells - maybe 1/3 of those are even HE-frags that can be used effectively against enemy positions. But that's ok, since there is the IFV just behind that could provide a higher volume of fire at longer durations.

limb wrote:
How many is arbitrary.

Most targets are going to be infantry type targets. Its not arbitrary.

limb wrote:
And now your utter ignorance is showing. Telescoped ammo is a very old technology from the early 70s and telescoped 40mm ammo is in service in the british warrior ajax IFV. Its a mature technology, more mature than 57mm 700-800m/s  APFSDS shooting grenade launchers. Autoloading mechanisms for telescoped ammo are also more mechanically simple.

Its a mature technology that almost nobody else uses. And Ajax is hardly a good example of a functional vehicle let alone a capable demonstratoin of the telescoped ammo.

Also the ability to accurately destroy tanks and IFVs and having more accuracy and faster shell speeds than an ATGM would makes a 76mm gun worth it compared to a 30mm autocannon paired with a 300m/s howitzer.

BMPs are not intended to hunt tanks... BMPs deliver troops and support troops by shooting at enemy infantry, enemy infantry positons, and enemy infantry vehicles.... both BTRs and BMPs... in western terminology APCs and IFVs.

The anti tank capacity is purely for self defence and in real combat might equally be directed at enemy helicopters or enemy IFVs as enemy tanks.

The new T-15 will have a 57mm grenade launcher that is also able to fire APFSDS rounds... these rounds will likely have a muzzle velocity of 1,200m/s or so with a penetrator longer and heavier than the penetrator in any 30 or 35mm calibre weapon simply because the volume of the round allows it. The 57mm high velocity round probably has an even heavier penetrator but the larger shell case with more room for more propellent should enable velocities of 1.5km/s which will be able to threaten even quite heavy targets from the side and rear... the point is that to get that extra performance they are bigger and heavier rounds that take up more space and remember this vehicle is not a tank it is a troop transport so the smaller ammo with slightly less performance has been chosen because it will be effective enough and is compact enough to fit inside the turret without taking up space in the troop compartment.

Remember the T-15 also has four Kornet-EM missiles and 8 Bulat missiles both of which can take down enemy armour.

The optics and communications in the T-15 means it should be able to hit targets out to very significant distances... beyond about 4km and it is unlikely they will be firing APFSDS 57mm rounds at moving targets because the hit probability will be too low... at such distances the missiles will be used to defeat the targets rather more efficiently or at closer distances if the target is moving rapidly or erratically or randomly.

With an attacking force of T-15s there are going to be plenty of anti armour weapons it will have at its disposal...

Many targets wont require armour penetration however so the HE round is most likely to be used whether against a bunker or even troops in the open a HE bomb is always more effective than solid shot...

That is why flak jackets were called flak jackets because fragments are more abundant and kill or injure more often than bullets do.

Also modern western IFVs are immune to 30mm AP-T shells, so your claim of needing "a couple of longer burts" is just your wishful assumption.

Enemy armour is getting better and 30mm rounds are becoming less effective so that is why they are moving to 57mm calibre rounds... 30mm remains useful against aircraft and troops and older vehicles and lighter vehicles... even APDS will shred an MRAP vehicle... but for their Armata forces they needed better penetration.

The T-15 turret we have seen so far has the Epocha turret with the 30mm gun, which for lighter vehicles like Kurganets and Boomerang might still be fine... remember they still carry 12 ready to fire anti armour missiles able to demolish armour or low slow aircraft... and these BMPs will be operating with tanks carrying 125mm guns which are quite suited to dealing with enemy armour too... in fact that is why they tend to be used together...

BS, MBTs, like IFVs are are there to support infantry, which means shooting at anything that can kill infantry. The way you claim MBTs choose targets is US doctrine, where tanks are expected only to destroy other tanks and vehicles.

Russian doctrine sees both Tanks and BMPs carrying direct fire HE rounds and anti armour weapons, but even in the Russian forces the BMPs wont go hunting tanks, and their infantry are well equipped with anti armour weapons too.

Its a mature technology, more mature than 57mm 700-800m/s APFSDS shooting grenade launchers. Autoloading mechanisms for telescoped ammo are also more mechanically simple.

The 57mm grenade launcher rounds follow the telescoped round philosophy even if they don't use the same coke can design... and we don't know what the velocity of the 57mm APFSDS rounds are... it could be 1.2km/s... it really depends on the weight of the penetrator and the propellent performance.... APFSDS are rather lightweight things and can accelerate rather quickly down a barrel depending on the propellent type and charge size.

Also the ability to accurately destroy tanks and IFVs and having more accuracy and faster shell speeds than an ATGM would makes a 76mm gun worth it compared to a 30mm autocannon paired with a 300m/s howitzer.

To get moderate velocities with a 76mm gun the total round would be enormous and heavy and take up a lot of internal space.

The 57mm rounds are more compact and clearly they expect it to be powerful enough to get the job done.

They aren't that myopic, since each tank still carrier a large complement of HE-frag shells. Still, there's only so much targets you can shoot with just 40 shells - maybe 1/3 of those are even HE-frags that can be used effectively against enemy positions. But that's ok, since there is the IFV just behind that could provide a higher volume of fire at longer durations.

The ammo load would likely be adjusted depending on the situation... if no enemy armour is expected or likely most rounds would be HE frag... perhaps with a few HEAT just in case...

Its a mature technology that almost nobody else uses.

This 57mm grenade launcher round sounds like a very good approximation of the concept... but we have no idea about how the mechanism actually works.

Certainly the core idea behind the telescopic rounds was to make the ammo compact and yet rather more effective in terms of HE performance and APFSDS rounds because of the available volume and length for the latter and the extra size and weight of the former that could be accommodated.

In many ways it is just a copy of the 125mm two piece ammo concept... for HE rounds and HEAT rounds that don't need high velocity the propellent stub is sufficient to send them down the barrel at 900m/s or so, with the other part of the ammo being all projectile allowing big rounds to be fired. For APFSDS rounds however the small narrow light dart shaped projectile held in a sabot also carries several kgs of extra propellent for extra speed for which the round benefits.

Essentially you have a small core propellent base that is sufficient for HE related rounds and a HE related projectile that can be huge, which benefits its performance, and a light compact high speed projectile with the rest of the projectile volume being extra propellent to boost speeds to 1,8km/s and faster because that is what AP rounds benefit from... the only short coming is that the APFSDS rounds penetrator cannot extend into the small stub propellent charge to make it slightly longer... but other solutions can be found and have been found for that.


With the 57mm grenade launcher round they have a much bigger APFSDS dart than that that could possibly be fitted into any 30 x 165mm case, with way more propellent than could be fitted in a 30mm case too, so the penetration performance is going to be much much better, but with a round that is not as big as the high velocity 57mm S-60 cannon round. At the same time the HE projectile is going to be vastly more powerful too because it is a much bigger round and is almost all HE bomb unlike the 30 x 165mm round, whose projectile is much smaller in size.