A bigger gun for lighter armored vehicles?

Earlier this year, I was intrigued to learn that Russia has decided to standardize on a 57mm. cannon (derived from the early-Cold-War-era AZP S-60 anti-aircraft cannon) for its next generation of infantry fighting vehicles (IFV’s) and armored personnel carriers (APC’s).  This is a development with both up- and downsides, and I’ve been trying to figure out the reasons behind the decision.

NATO and other armored vehicles are also in the process of being “up-gunned” in various countries, although not (yet) to as large a caliber as 57mm.  The US Bradley‘s M242 Bushmaster 25mm. cannon (using shells about 1″ in diameter) proved very effective in both Gulf Wars, capable of destroying even former Soviet Cold War-era main battle tanks when engaging them from the side or rear.  Recent developments have included:

A 57mm. shell is approximately 2¼” in diameter.  It’s no longer a light cannon, and its ammunition is considerably larger and heavier than that of a smaller-caliber weapon.  Vehicles can carry many hundreds (in some cases, even thousands) of rounds of the latter, but perhaps no more than 100-150 rounds for the bigger weapon.  That may pose difficulties in an extended combat situation, where resupply is difficult or dangerous.  Of course, each larger round is considerably more effective than each smaller one;  but they have to hit their target in order to be effective.  With the larger cannon, one can’t afford to miss very often, for fear of wasting ammunition.  To be sure, modern targeting systems make it easier to get a first- or second-round hit;  but if they’re disabled, one goes back to “ye olde Mark 1 eyeball” to hit something, which isn’t nearly as accurate.  In combat in Angola in the 1980’s, we carried, and could afford to spray, hundreds of rounds from the Ratel IFV’s 20mm. cannon (and our Angolan and Cuban opponents could do likewise with their very effective ZU-23-2 23mm. weapons), both sides knowing that at least some of them were likely to connect.  With a modern large-caliber cannon, such profligate expenditure of ammunition simply won’t work.  One can’t carry enough rounds to be able to afford to miss with them.

Effectively, the larger-caliber main gun of an IFV or APC will no longer be a primarily anti-personnel weapon.  It’ll be there to take on enemy IFV’s, APC’s, and perhaps even main battle tanks, as well as gun emplacements, static defenses, and defensive missile teams.  The latter is a primary reason for the heavier caliber gun – its longer range.  When highly effective infantry-portable missiles such as the Javelin can reach out to 2½ miles (in its latest version), an armored vehicle simply daren’t get within range of them.  It would be too easily neutralized.  It has to keep its distance and shoot at the missile teams, vehicles and emplacements until it’s sure it can advance in relative safety.

That also means it has to rely on sophisticated optical, infra-red and laser sighting systems to detect the enemy, even when well camouflaged, and ensure its rounds will be on target.  Therein lies another vulnerability.  If an enemy can disable or destroy those sighting systems, the long range of the vehicle’s gun simply won’t matter – it won’t be able to put its rounds where they need to go.  Even relatively unsophisticated weapons, such as machine-gun fire or anti-personnel “beehive” or canister rounds fired from a cannon or recoilless rifle, can accomplish this, even if they can’t penetrate the vehicle itself.  I witnessed the effectiveness of such tactics and equipment during the 1980’s.  Airburst artillery rounds can accomplish the same thing, even without scoring a direct hit.

Some might argue that such a vehicle, armed with such a weapon, can simply “stand off” from such dangers, and eliminate them before getting close enough for them to be effective.  That’s all very well if the battlefield allows it, and if one’s sighting systems allow such threats to be detected at stand-off ranges:  but if that’s not the case, then the advantage of the heavier cannon is reduced or even eliminated.  In a bush warfare environment in Angola, where line-of-sight was frequently measured in tens of yards only, I saw UNITA guerrillas dig narrow foxholes, so deep that a fighter could stand upright in one with his head below the surface of the ground.  No thermal or other sight would detect them in such fighting positions, and they were almost invulnerable to air raids or artillery bombardment.  They could (and did) remain out of sight until enemy vehicles had passed overhead, then climb onto a box or other step in the bottom of the hole and send an RPG-7 grenade up the tailpipe of whatever had just passed – be it a tank, an APC or a truck.  The Cubans and Angolans lost more than a few vehicles that way (not to mention their crews).  In urban warfare, there are similarly short lines of sight.  An enemy can remain hidden in rubble or ruined buildings until a tank or APC is so close he can almost reach out and touch it, then use a weapon against it.  Even a primitive Molotov cocktail is likely to damage or destroy delicate sighting systems, rendering the vehicle’s weapons combat-ineffective.

The traditional answer to such threats has been to have infantry advance with armored vehicles, each protecting the other.  However, a bigger, heavier cannon on the vehicle may make it dangerous for troops to be too close, due to increased blast, noise, and the larger visual signature (dust kicked up by firing, etc., making it easier for the enemy to direct counter-fire).  There’s also the issue of active protective systems, such as the well-known Israeli Trophy (soon to enter service with the US Army).  These can effectively defend vehicles against incoming rockets and missiles;  but their explosion might also injure or kill infantry moving close to the vehicle.  See for yourself in the actual combat footage below.

There has so far been limited combat experience with infantry moving in close proximity to such systems.  I expect it to be problematic as more of them come online.  Infantry may be supposed to move alongside vehicles, but if that means they’re more likely to be injured or killed by the vehicles’ defensive systems, then no matter what their orders may be, they won’t do so.  They’re not stupid!

I suppose these larger cannon are trying to answer a question that hasn’t yet been properly – or, at least, openly – discussed.  In future warfare, as far as front-line combat is concerned, does infantry still have a role on the battlefield?  Is combat going to develop into a slugging match between vehicles, and possibly between unmanned systems or artificial-intelligence autonomous weapons systems?  If so, the new, heavier cannon on IFV’s and APC’s make sense.  If not – if infantry still have their traditional role in battle – then I’m not so sure.  I think a lot of this will have to be worked out in actual combat, where people learn the hard way what works and what doesn’t, and pay in blood and bone to find out.  Certainly, the US armed forces are having to rethink their equipment and training after almost two decades of fighting guerrilla-style opponents in Afghanistan and Iraq.  Conventional adversaries won’t fight the same way, will be equipped with much heavier and more capable weapons, and will need different tactics and equipment to prevail against them.  Firepower alone won’t do it.

It’s an interesting conundrum.



  1. The Russians have always wanted their IFVs to be light tanks that also carry infantry. Hence the BMP-1's 73mm and the BMP-3's 100mm + 30mm. Plus ATGMs.

    A heavier gun makes a lot of sense when you realize that futurewar™ is only or primarily going to happen in and around cities. Buildings are no longer wood with a brick facade – they're reinforced concrete and steel. We learned from combat as early as the very brief Soviet constitutional crisis (1993) that small caliber autocannon have almost no effect on modern buildings. Even Iraqi mud huts survive direct strikes with a 25mm. It just makes divots, until you pound through and make a breach.

    I'm all for upgunning IFVs to 40mm. More than that, and you run out of ammo too quickly. It also has proximity fuses, so you could quite easily build AA variants, useful for hunting drones. (Add in a couple of dismounts with SAMs, and it would be quite capable of local air defense.)

    Personally, I'd build a light force with a mix of 25mm and 40mm autocannons (deployed in pairs), along with the dual 120mm AMOS (automated mortar) for direct and indirect fire support. Leave tank busting to the tanks and ATGMs.

  2. Russians are probably basing this decision on combat experience. My guess is Syria, more than Ukraine. The modern building hypothesis makes sense.

  3. The 57mm is an interesting choice. Being ADA, the projectiles should have a high muzzle velocity and flat trajectory, so it's a case of acquire target and fire. You can put a substantial sabot into a round of that diameter, to kill IFVs and disable or degrade MBTs. A HESH round would also do a lot of vehicle damage and make breaching easier. Another thing to consider for MBTs is the increased amount of electronics and cabling installed in them. The shock impulse from a 57mm direct hit might disrupt control buses and knock internal boxes loose. Vehicle shuts down for at least a few seconds.

    Urban warfare will include operating around a lot of reinforced structures, but also a lot of mud/adobe buildings, CMU walls, and misc. shacks. A larger cannon round, such as 40-57mm, allows vehicle commander to carry HE, HESH, AP, incendiary, and smoke. With medium or heavy mortar support, these can clear a lot of area for infantry ops.

  4. The larger rounds, 40-57mm, are also effective anti-helicopter rounds (when equipped with proximityfuses), which I suspect is helping to drive this size increase. I expect they're keeping coaxial machine guns for pure infantry support, along with several thousands of rounds for them. Maybe a .50 caliber up top, as well?

  5. the demise of Infantry on the battlefield has been predicted since tanks were introduced in WWI

    Vehicles tend to have a little bit of trouble going up and down stairs to clear buildings.

    There may be a day where man-sized robots are able to replace scared 18 year olds, but there will always be a need for man-sized combatants to go in and dig out the defending troop (think the tunnel warfare in the Pacific during WWII for the extreme case)

    Especially since it is no longer approved to just bury the enemy under rubble and let them die due to the civilians they will have around them.

    The Navy has also had the "marines won't be needed, we can flatten the enemy with out main guns" mentality pop up periodically, but that has been shown repeatedly to not be the case.

    Vehicle-only battles will happen, as they did in the deserts of the Gulf Wars, but you cannot plan to have your enemy cooperate with you to always be that way.

  6. Bigger isn't always better. Bigger means less rounds carried, and as others have said, damage to the supporting infantry if they are too close when the guns fire…

  7. Very interesting. We are repeating a trend we saw starting right before WWII, with light vehicles carrying either big machine guns or small cannon, up to 25mm, and then the move to 37mm (with the Brits jumping the gun to 40mm) and then 50mm and then 57mm and then low to medium velocity 75mm guns and low velocity howitzers.

    So this is what I predict. MBT main guns will get larger (Germany has proposed a 130mm smoothbore, mainly because they refuse to use depleted uranium rounds.) I think I read where the Russians were thinking 140mm or 150mm (again, like during and after WWII.) Effectively the 'cruiser' tank will become the 'heavy' tank, again.

    So 'light' vehicles, like the IFV and such, will up-gun, basically becoming 'medium' vehicles for all purposes. Guns will head between 40mm and 75mm of various velocities, the larger diameter the less velocity.

    And then there will be introduced a number of new 'light' vehicles running 'new' 20mm-30mm gun systems as 'light' vehicle killers…

    And then the cycle will repeat.

    We see this with cars with small econo car is released, morphs into a mid-sized mid-level car and then becomes a large cheap luxury knockoff-mobile. Meanwhile, a new small econo car is released, and starts climbing in size, luxury and price, then another small econo car…

  8. a potential problem with these new reactive systems is the reaction is so overwhelming that it may be confused with the target being hit.

    How effective are these systems at dealing with two incoming threats nearly simultaneously? I would consider two launches to become the new tank killing technique, as I suspect the reaction will momentarily overwhelm the sensors. Maybe a duplex round, with the following warhead slowed in some fashion to arrive a second later?

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