BMP-1 and BMP-2 in Russian Army

Just a quick question what was the reasoning for soviets developing the 73mm grom gun for bmp-1 while they were already using the 76mm gun on the PT-76?

I would turn that around and ask what real practical advantage does standardising calibres for different weapons achieve?

I mean a 122mm tank gun/artillery piece and a 125mm tank gun, not to mention the 120mm mortar and indeed the 122mm Grad rocket.

The 122mm round of the D-30 and 2S1 is not compatible with the 122mm round of the IS-3, and the Grad rocket can't be fired by either gun as well.

Imagine it is WWII and you have some accountant called up for service and he gets a call for 7.62mm small arms ammo... now does he send 7.62x38mm rounds for Nagant Revolvers, or 7.62x54mm rimmed cartridges for MGs and rifles... or does he risk sending 7.62x25mm rounds for TT-33 pistols and SMGs?

If the unit is armed with Mosin rifles and DP28 LMGs and Maxim Machineguns they wont want 7.62x25mmm ammo as only the officers pistols can use it, but then if the unit has mostly PPSh-41s then 7.62x54mm R rounds are not so useful either.

Of course with small arms the same machine that makes machine gun barrels can make rifle barrels and SMG barrels and pistol barrels too... indeed in the immediate post war period they could also make SKS carbine barrels and AK assault rifle barrels and RPD LMG barrels too.. all the same .311 calibre.

The 73mm gun on the BMP was intended to penetrate enemy tanks within about 600m, which no 76.2mm gun of the time or since could be relied upon to do.

Both have similar penetration and the 76mm has a little more range. I know that spg-9 uses same calibre and similar rounds but effectively they already had a turret on the pt-76 and the pt-76 wasn't getting decommissioned anytime soon.

The 73mm gun was a cheap recoilless rifle type weapon but closed off for firing from a turret, except it was a simple smoothbore weapon... it was pretty much a super RPG-7 to fill the gap created by the minimum effective range of the AT-3.

When the AT-4/5 launcher was adopted, the 73mm gun became redundant in terms of anti armour performance, but by then they realised that direct fire HE rounds bigger than 30mm cannon shells were useful against some targets.... and by then a HE rocket had been developed and deployed.

Note from the first production the BMP-1 had a button to load HE rounds but they weren't issued for a long time.

The Russians developed a BTR with a 85mm gun and the Cuban's have even mounted a T-55 turret on a BTR-60. So 57mm would be no problem. (I posted pics of the Cuban BTR on this forum Cuba section)

Tank armour overtook medium sized gun capacity very quickly... leading to the adoption of missiles to replace them.

The Soviets learned that HE fire power was useful for an IFV so they kept the 73mm gun and replaced it with a rifled 100mm gun... not the rifling is key...

The 73mm gun of the BMP-1 and 125mm gun of their tanks are smoothbore because their primary rounds are HEAT and APFSDS that don't like to be spinning, so that means they are primarily for anti armour use.

the rifled barrel of the 100mm BMP-3 gun is because its primary round is a HE shell that benefits from spinning.... the other round is a missile with fins and slip rings so it does not spin so its HEAT warhead has full effect on target...

The 85mm gun on the BTR was an anti tank gun... like the airborne ASU-85... it became obsolete, because even in rear areas tank armour is too thick to be reliably penetrated by such a low power gun.

A lot pressure gun like the 100mm BMP gun means good calibre for good penetration for its guided missile round but also a nice compact short stubby round to deliver a heavy HE projectile at a sedate pace with not too much recoil and just enough range... early rounds 4km, later rounds 7km.

An 85mm gun would have a much larger shell case but a lighter projectile so in comparison against targets within 7km the 100mm round might take several seconds longer to arrive but will make a bigger bang and be more effective when it does arrive and its calibre is large enough for a practical guided missile to be used, while 85mm would be too narrow.

There isnt much difference between bmp -1 and bmp-2 in armour and remember it's a mix between armour mobility and speed something too heavy and it's becomes slower the made objectives is to transport troops under armour to protect against shrapnel and small arms and provide some fire support.

The original idea was that it was WWIII and everything is radioactive so you stay in the vehicle and it rolls up to the enemy position and you stay on board to fight... they quickly worked out the flaws in that plan and realised that a better use is to deliver troops to near the front line... a few kms short and have the IFV withdraw a bit and offer fire support for the tanks and troops as they moved forwards into the enemy positions... in this case the BMP-3 could do what western IFVs and western tanks do... offer auto cannon fire and heavy HE support, but by using the 30mm cannon and 100mm rifled gun it is able to fully support the troops, so the tanks can concentrate on enemy armour if present as well as supporting the troops advance with accurate direct fire heavy HE rounds.

If the enemy has no armour you could even operate some IFVs and tanks together as a mobile force that could then attack from a flank on the enemy position with the other IFVs supporting the infantry attack from a few kms back.

Still not massively different in terms of creating a new calibre and gun. The 76mm would have done the job.

The requirement was for frontal penetration of the enemy MBT of the day out to about 800m... which would have been an M60 tank... I doubt the 76.2mm or 85mm would have coped with the job.

In practical terms if an M60 appeared at 300m out to 3km they would have used the AT-3 to engage it, so the 73mm gun would really only have been used out to perhaps 500m against enemy armour and perhaps 3 times that range against troops with HE rounds.

And chassis can still be useful and bmp-1 chassis is still perfectly useful while grom has largely seen criticism.

It was useful enough to justify a large calibre replacement despite no longer being necessary... AT-4 and AT-5 missiles made it largely obsolescent in its primary role, but its secondary usefulness made a replacement necessary.

Note next gen IFVs with 57mm guns and missiles will be a half way house where the 57mm gun wont have the HE power of the 100mm rounds, but will have much better anti armour effect than 30mm shells, and with airburst rounds and guided rounds will be rather more useful than the 30/100 combo.

I would say the cheapest upgrade for the BMP-1 would be ATGM launch platform... a range of missiles... Metis-M1 for very short range engagements, plus Kornet for longer range use... the former cheap and small and light, while the latter is heavy but much longer range and better performance over much greater distances.

Whats more BMP-3M also is not perfect support vehicle due to insufficient RPG/ AGTM protection.

Add ERA to reduce the effect of any spillage, but an APS like ARENA-2 would pretty much make ATGMs and RPGs ineffectual most of the time...

I did ask the reasons why they didn't use 76mm as it was already in service

They didn't use the existing 76.2mm gun because it was not suitable for a troop transport vehicle and could not be fitted to a one man turret as used in the BMP-1.

They went through a lot of designs including wheeled and mixed half track and fully tracked designs when evaluating the BMP-1... half tracks deemed too expensive and reduced mobility over fully tracked vehicles.

They even had a model armed with an automatic cannon, but it had no way of defending itself from enemy tanks inside the 300m minimum range of the AT-3 so it was rejected in favour of the 73mm gun, which was just a low pressure rocket launcher with the rear end blocked off.

In fact for the BMP-2 there was a higher pressure larger calibre 85mm weapon similar in concept to the old 73mm weapon, but the new AT-4 and AT-5 ATGMs rendered the need to penetrate MBT armour at close range unnecessary, so they went with a 30mm cannon.

During operational experience it was found that direct fire larger calibre HE was actually useful against some target types, while the 30mm autocannon was also found to be useful (but generated lots of fumes in the turret when fired at the top rate).

The solution was a 100mm gun with a very useful HE round, and the 2A72 30mm cannon with a longer recoil stroke and lower rate of fire leading to elimination of the fumes problem in the BMP-3.

Tests of latest BMP-2M infantry vehicle to be completed by December - source

The vehicle received a new module with a fire control system, improved crew awareness, new commander and gunner sights, automatic grenade launcher, and an anti-tank system

MOSCOW, November 3. /TASS/. The upgraded BMP-2M infantry fighting vehicle equipped with the Berezhok combat module will complete state tests by December 1, 2019, a source in the military-industrial complex told TASS.

"The BMP-2M with the Berezhok combat module is a deep modernization of the BMP-2 in service. Currently, state tests of the newest vehicle are underway, they should be completed by December 1," the source said.

The vehicle received a new module with a fire control system, improved crew awareness, new commander and gunner sights, automatic grenade launcher, and an anti-tank system. "Two missile launchers of guided anti-tank missiles Kornet, two missiles each, were installed in the fighting compartment of the BMP-2M," the source added.

It was reported earlier that the Far Eastern military command high school received a batch of upgraded BMP-2M infantry fighting vehicles. The number of vehicles supplied in 2019 exceeded 20 units, the Defense Ministry said.

BMP-2M is a BMP-2 modification with the Berezhok combat module. It transports troops, increases their mobility and protection on the battlefield.

https://tass.com/defense/1086734

Well, for the new vehicle families they will have had to develop new equipment and electronics sets to equip each vehicle, so practising on existing vehicles probably isn't the worst idea as you can use the next few years testing and getting it right while the final vehicles are being finalised...

The concept of modular systems on a vehicle base can be exported to allies and customers while they further work on their new familes for their own use I guess.

In a way it is like Ratnik where previously each piece of equipment a soldier carried or used was created independently and largely without really taking in to account all the other things that soldier was using and wearing and carrying.

A core feature of Ratnik is that different things can be integrated together and some things can be replaced by multifunction items to reduce costs and lighten the load and just make things better.

I suspect modular equipment between the old and new vehicles could mean first of all an enormous upgrade in performance for existing kit... just look at all the improvements on the BTR-82 as an example of correcting minor and major problems to improve performance and communication and fire power.

I don't know how true it is, but there was a rumour or belief that the Soviet Army used to train on older generation vehicles to get the crews trained to a basic level first and then they would use the new vehicles for final training... this was supposedly to reduce wear and tear on the new expensive stuff, but also to give the soldiers a good grounding in the old stuff which they might find themselves using in combat... for example in Afghanistan in the 1980s it was decided to use upgraded T-55s and T-62s instead of newer tank models because the lack of enemy armour made better vehicles unnecessary. Of course the old model tanks were fitted with add on armour and laser range finders and other modernisation kits... including Drozd APS systems experimentally, which resulted in them being good enough for the job.

They are going to have to develop and evolve new tactics and plans regarding the new capabilities their new vehicles are going to allow them to implement... new and more capable stabilisation systems for the weapons... new weapons with much longer reach because they are better stabilised, not to mention much better day and night optics that will further allow detection, identification and engagement to take place at much greater distances, not to mention improved navigation and information from external platforms like UAVs they might even be launching themselves... or information about enemy forces from aircraft and other units placed on their maps automatically, and their ability to add target information to that map to share with HQ and other units as well will change the way things work.

Artillery and air support will likely be much more responsive and therefore more often used... half the time an armoured force might just use their onboard sensors to find targets that can be marked with lasers and engaged by artillery or air power, or even vehicles within the unit using stand off weapons like 10km range Kornet missiles or 13km range with 120mm rounds from gun/mortar vehicles...

Getting some of those systems into older vehicle types will greatly improve their performance and allow earlier in field testing of systems and tactics and increase production of components for new vehicles hopefully making them cheaper and ironing out the bugs before the new vehicles enter service.

Well the fact is that there are probably just as many BMP-2 and BMP-1 vehicle chassis in operation doing jobs other than transporting troops than there are IFVs, just like all the different MTLB chassis and BTR vehicles being used for engineer vehicles and ambulance and command and communications and recon and other duties in any Russian armoured unit...

It is going to be all those other uses of vehicles they will need for the first new vehicle units... I can't see them having every type of vehicle platform ready in Armata based vehicles for the first Armata unit... perhaps they will start out with Armata battalions, then Armata regiments and then Armata brigades or divisions... the new kit and equipment fitted to these BMPs could be new stuff designed for the new vehicle families so they can get them in to service and see how they stack up with existing types and then fit them to the new vehicles as they are produced with any modifications needed... while in the mean time transfering the BMP based models to standard units where there are other BMP based vehicle types anyway.

A batch of 18 upgraded BMP-2M infantry fighting vehicles will arrive for Russia’s 201st military base in Tajikistan in 2020, the press office of the Central Military District reported on Tuesday.

https://tass.com/defense/1111213

I recall an interview where they said that the Kurganets-25 was basically a further development of the BMP chassis but with the engine mounted forward.

Well the BMP and BMP-2 both had front mounted engines anyway... it was only shifted on the BMP-3 because the frontal armour and weight of the turret rendered them too front heavy to swim properly...

BMP-2M IFV with a Berezhok combat module in Alabino military training ground

BMP-2 crews overcoming a water obstacle and firing from the Fagot ATGM in a training exercise in the Moscow Region

I can imagine the tantrums in the west over the Russian Army shooting faggots during exercises...

Being sensible, the launcher itself is a sophisticated number designed to fire Faggots or Konkurs.... western designation AT-4 and AT-5 ATGMs... they are basically the equivalent of Milan and HOT ATGMs.

Bmp-1 gun isn't really precise and led to its replacement by bmp-2.

If it was not accurate enough it never would have entered service.

The BMP-1s 73mm gun is pretty much a closed end SPG-9 73mm rocket launcher.

It was the main armament of the BMP because the ATGM used to start with was the AT-3 which couldn't hit a target within 500m because the few seconds it took to gather the missile and get it under control (being a manually steered missile). That meant that tank targets that were within 500m had to be engaged with the 73mm gun, which was its purpose. Hitting a 3m by 3m target out to 500m with the 73mm gun was easy as long as it wasn't moving.

The 73mm gun could penetrate an M60 at any range it hit it from any angle.

The BMP-2 has a 30mm cannon because the AT-3 was replaced by an AT-4 and AT-5 launcher whose minimum range for targets was about 50m so the ability of the main gun to penetrate a tank was no longer a requirement.

The HE power of the 73mm gun actually complimented the high velocity 30mm cannon so both vehicles were kept in service together and the replacement vehicle for both was the BMP-3 which replaced the 73mm gun and missile launcher with a 100mm rifled gun and missile launcher and it also has a 30mm cannon too.

The BMP-3 wouldn't use its 100mm gun against enemy IFVs... it would use its 30mm cannon... in a mixed force of BMP and BMP-2s the 73mm gun would be used against targets the 30mm is not so suitable for.

bmp-2 had fagot.

The launcher on top of the BMP-2 was a dual system able to fire Fagot and Konkurs... so the French equivalent would be a mount that can fire Milan and HOT...

The BRDM-2 with the fully retractable five shot launcher could carry Fagot or Konkurs or both... it could carry 15 missiles if it was only carrying Konkurs, but when carrying the smaller Fagot it could carry 10 Konkurs and 10 Fagot, so it meant an extra 5 missiles at the cost of 10 missiles needing to be fired at targets 2.5km or less away.

Funny that in western military sources they ridiculed the BTR series, but as you point out... they were amphibious and had rather good cross country performance... central tire pressure regulation systems so you could reduce tire pressure for better traction on sand or snow or ice, and while not super protected they were better than a truck. The M113 APC wasn't that well armoured either... often grenade fragments and AP rifle bullets could penetrate it from the side.

In Afghanistan a BTR could carry on after running over a land mine... perhaps losing a tire but able to crawl away still...