Why a ship's close-range cannon loses to a drone swarm
In April 2026, in Sevastopol, according to Ukrainian and Western analysts, the destruction of two Project 22460 border patrol ships (PSKR) was confirmed. The attacks were combined: Ukrainian unmanned boats (UBK) with warheads were launched from the sea, and swarms of unmanned aerial vehicles (UAVs) were launched from the air, with up to 43 units launched in a single night. Both damaged PSKRs were equipped with the same standard naval equipment. artillery close-in self-defense system - a six-barreled 30-mm AK-630M. The same gun is installed on dozens of other Black Sea Fleet ships. fleetFrom missile From boats to frigates and landing ships. It's also the ship's last line of self-defense, designed to operate against both sea and air targets simultaneously. It failed to fully engage either.
This isn't a question about the calculations. And it's hardly a question about the gun itself. It's a question about the class of systems to which it belongs and the task for which it was designed half a century ago.
How the AK-630 works
The system was developed by Tula designers V. P. Gryazev and A. G. Shipunov. Design work began in 1963 and it was accepted into service in 1976. It is an automatic naval gun mount with a rotating barrel block, operating on a Gatling principle. Its intended purpose is to serve as a ship's primary means of close-in self-defense. It finishes off targets missed by long-range and medium-range aircraft, including anti-ship missiles, aircraft, and helicopters. It can also engage floating mines and light boats.
At its core is the AO-18 six-barreled assault rifle. Unlike its Western counterparts, which are electrically powered, this one is gas-operated. It has a 30mm caliber, a 30×165mm cartridge, a muzzle velocity of approximately 900 m/s, a rate of fire of up to 5000 rounds per minute, and an effective range against aerial targets of up to 4 km.
Five thousand rounds per minute is a figure that's easy to remember, but requires some explanation. There are six barrels, and each barrel fires approximately 833 times per minute, or one shot per barrel approximately every 0,072 seconds. Between shots, the barrel is cooled by a closed-loop water circuit within the casing. Ammunition capacity is 2000 rounds, belt-fed; replenishment occurs from the under-turret compartment.
The mount rotates on a platform with an electrohydraulic drive. It traverses at a rate of 70°/s horizontally and 50°/s vertically. This means a 180° turn takes approximately 2,5–3 seconds. Elevation angles range from -12° to +88°: the gun can fire almost straight up and down, but there are dead zones between the extreme angles—at the water's edge and above the ship's masts.
The mount itself doesn't provide guidance. Guidance is handled by a separate shipboard fire control system, which is integrated with the SP-520M optical-electronic post, standard on the Project 22460 PSKR. The fire control systems of a number of naval ships also utilize the MR-123 Vympel radar (NATO reporting name: Bass Tilt). The radar operates in the X-band, and its antenna is mounted on a mast. One such post can control two AK-630s or one AK-630 and one 76mm AK-176.
What was it made for?
To understand why the AK-630 is currently reaching its design limits, we need to go back to the time of its creation. In the late 1960s, the main threat to surface navies was considered to be low-altitude anti-ship missiles. The benchmark for such weapons The American Harpoon missile, adopted into service in 1977, became the first to achieve this: range of about 120 km, flight altitude of 10–15 m above water, speed of about 240 m/s, warhead of about 220 kg.
This was the threat profile for which the Close-In Weapon System (CIWS) class—the ship's last line of self-defense—was designed. The logic is simple. Long- and medium-range air defense missile systems (SAMs) intercept incoming missiles. If they miss, the ship has only seconds left, and in those seconds, it needs a system capable of delivering the densest possible stream of submunitions into the air at a range of up to 4 km. Preferably, this should be done automatically, without operator sway.
Everything is designed for this task. The burst is short and dense, ensuring that at least one in a hundred shells hits the warhead or missile engine. The range is 4 km because at this distance, a subsonic missile covers its final section in 15–20 seconds, and during this time, it must be engaged and the result assessed. The rate of fire is high because there is only one target, large, and following a predictable trajectory. The control system has a single channel because one gun doesn't need to fire at two missiles at once: the second is assumed to be reached by a long-range air defense system or an adjacent ship in the formation.
Secondary objectives—targeting aircraft, helicopters, light boats, and floating mines—followed the same logic. Targets were single or few in number, appeared predictably, and were destroyed with short bursts.
This concept worked remarkably well. American naval publications openly note that the CIWS class was designed for a single launch or a small group of no more than three or four missiles per salvo. In such scenarios, the AK-630, Phalanx, and Goalkeeper demonstrated exactly what they were designed for.
What's up with the neighbors?
It makes sense to look at how the same problem was solved in the West, so that it becomes clear: the limitations that the AK-630 ran into were limitations of the class, and not of one specific development.
American Mk 15 Phalanx
Dutch goalkeeper
Spanish Meroka
The American Mk 15 Phalanx uses a six-barreled M61 Vulcan 20mm cannon with a fire rate of 4500 rounds per minute and an effective range of 1,5–3,6 km, depending on the modification. The Dutch Goalkeeper is built around a seven-barreled 30mm GAU-8/A cannon—a naval modification. aviation The A-10 Thunderbolt II attack aircraft's cannons fire at a rate of 4200 rounds per minute and have a range of approximately 2–3 km, depending on the target type. The Spanish Meroka is an unusual design consisting of twelve 20mm barrels, producing a salvo effect at a range of 1,5–2 km.
All three are directly comparable to the AK-630 in their intended purpose. The Phalanx and Goalkeeper have their radar integrated into the mount itself, while the AK-630 has its mounted on the mast. The Phalanx is lighter, the Goalkeeper is heavier, but the architecture is the same: the radar tracks a single target, the computer calculates the lead, and the gun fires a dense burst.
The main similarity isn't in the ranges or calibers. The key is that all these systems can track and engage exactly one target at a time. A radar can maintain a search sector of several dozen objects, but it can only track one target for fire. This isn't a flaw in a specific model; it's a fundamental feature of the class, inherited from the 1970s mission.
Phalanx Block 1B received an optronic channel and the ability to engage surface and low-speed targets, expanding the threat landscape but not fundamentally changing its single-channel tracking capability. No existing CIWS is capable of tracking two targets simultaneously. US Navy technical reviews explicitly state this limitation: the class cannot be scaled in channel count without a complete architecture overhaul.
Where the system hits the ceiling: air
Now, some simple arithmetic that explains Sevastopol in April better than any statements from the parties. And it must begin with the airborne portion of the raid, because it reveals the basic limitations of the class.
Roy drones is coming on a broad front. The April 2026 attacks, according to Ukrainian and Western analysis, involved 20 to 40 drones launched in a single attack within half an hour. Approach speed drone It's slower than an anti-ship missile, but it's also detected later: its plastic casing, low radar signature, and flight close to the water or at low altitudes. The actual window from detection to critical range is 60–90 seconds.
What does the AK-630 with the SP-520M control system manage in these 60-90 seconds? According to expert estimates, acquiring a new target after losing the previous one takes about 5-10 seconds. This isn't a matter of calculation, it's a matter of physics: the radar must reposition itself, identify the signature, tune out clutter from the sea and shore, and transmit the data to the computer. Hitting a single target with a short burst takes another few seconds, plus the evaluation of the result. Total time for one target from start to finish is 10-15 seconds.
Ten targets times ten seconds equals one hundred seconds. And the system has ninety seconds. This simple arithmetic alone shows that a single AK-630 launcher alone can't cover a swarm of even ten devices. If there are twenty targets, the picture becomes dire: the crew will only have time to handle four or five, and the rest will pass without any fire impact.
The approach geography is also factored into the equation. If the drones are approaching from the same direction, within a sector of approximately 45°, reorienting them takes a fraction of a second and has almost no effect. If the front expands to 90°, azimuth rotation is activated. If they are approaching from diametrically opposite directions—from two sides at once—the turn takes up to 3 seconds, including the mechanics alone, without acquisition or targeting.
Next comes altitude. If the same swarm includes both 50-meter and 1000-meter aircraft, the barrel has to be adjusted vertically by tens of degrees. That's another second. And another second to recalculate the lead for different approach geometries.
And finally, interference. The MP-123 has elements of protection against electronic countermeasures, but against modern portable X-band jammers, the radar is forced to switch to backup modes or yield to optics. Optics perform worse at night. In rain and fog, it's even worse. And the Ukrainian side prefers to attack at night.
This is the basic limit of aerial work. But in April, there was more than just sky.
Where the system hits the ceiling: the sea
Parallel to the air attack, Ukrainian unmanned boats were patrolling the Sevastopol roadsteads. A Magura V5 or similar unmanned boat is a small vessel approximately 5–6 meters long, with a warhead weighing approximately 250–320 kg. According to open sources, the cruising speed of such a craft is up to 20–25 knots, with a maximum speed of 40 knots or more; during the final leg, the unmanned boat often jerks forward, traveling almost at the water's edge. For the AK-630, this is a fundamentally different target profile than a drone or missile, and adds just as much complexity.
First problem — detection. The MP-123/SP-520M X-band radar, at the distances required for effective cannon operation, poorly distinguishes a small, low-flying vessel from sea reflections. Against a background of waves, the BEK produces a signature comparable to that of a large boat or even a large wave. The optical channel can detect it, but only at short distances, when the boat is already within the engagement zone. Early detection, which allows time for reaction, is not the responsibility of the cannon or its own radar, but of external assets: shore posts, reconnaissance UAVs, and shipborne surveillance radars. In reality, this means that the AK-630 begins to engage the BEK when it is already 1,5–2 km from the ship. In other words, half of its nominal range is already lost.
Radar station MR-123 "Vympel"
Second problem — geometry. The AK-630's elevation angles drop to -12°, and technically the gun can hit the water's surface alongside the ship. But "technically" is the important word here. At ranges less than 500 meters, the target's angular velocity relative to the ship becomes comparable to the mount's azimuth rotation speed. 70°/s is a lot against a drone at a kilometer, but very little against a drone passing alongside at 300 meters. The mount simply doesn't catch up with the target's angular velocity.
Third problem — dead zones. A ship isn't in a vacuum. It has superstructures, masts, other installations, and antennas. A gun mount physically can't cover some sectors around the ship's side: the barrel rests against its own deck or superstructure. A drone approaching from the stern or under the bow enters these zones. There, only a machine gunner at the side or a missile system with a different field of view, if one is present, can reach it.
The fourth problem — lethality. A 30mm projectile effectively rips apart the aluminum casing of a missile or the plastic hull of a drone. Against a drone with a plastic or composite hull and redundant electronics, a single hit may not be enough. Several are needed, preferably at the nose, where the fuse and warhead are located. In rapidly changing terrain, this is more difficult to achieve than against a uniformly moving missile.
When they come together
Each of the two threats, individually, is already pushing the AK-630 to its limits. When they arrive simultaneously, the effect doesn't just add up—it multiplies.
The gun crew receives input from two physically different directions. Aerial targets are overhead, flying at 50–500 meters, and have low radar signatures. Naval targets are below, near the water, also hard to detect, but against the sea, not the sky. The MR-123/SP-520M radar can track only one target at a time, meaning that within the same minute of operation, the crew must also switch between two threat types with different priorities.
Priority itself is a separate issue. A kamikaze drone carries a warhead weighing several kilograms and poses a risk of hitting the superstructure, antennas, and people on deck. A drone carries 200–300 kg and poses a risk of penetrating the side below the waterline. Which priority is more important depends on the type of ship, its displacement, its condition, and the distance to the pier. This decision must be made by the commander in real time, in conditions of noise, darkness, and incoming data. And while he's making that decision, the gun's firing cycle is wasted.
It's important to distinguish here: the defenses of ships of this class were designed to withstand a different threat, and today's combined attack is not a scaled-up version of the old task, but a new, dual one.
Taken together, this creates the picture we see in the April episodes: the cannon fires, the crew works, some of the targets are shot down, but some of the downed aircraft fall outside the water area—including, according to reports from both sides, on urban development—while some of the attacking weapons still reach the piers and ships.
The Economy of the Last Frontier
The AK-630 has one characteristic in which it clearly outperforms any Western equivalent: the cost per round. According to open estimates, a Russian-made 30mm round costs approximately $5-10. A round for the Phalanx is approximately $40-50. A round for the Goalkeeper, which uses the 30×173mm GAU-8/A family ammunition, is close to the same price range.
If a short burst of 10-20 shells hits a single target, that's a hundred dollars per kill. Against a $1,5 million Harpoon missile, that's a stellar ratio: one to 15,000. The CIWS class was designed for this kind of cost-effectiveness. The defender spends pennies, the attacker millions.
With drones and unmanned aerial vehicles, this arithmetic is reversed. A Ukrainian kamikaze attack drone costs, according to various estimates, from several thousand to tens of thousands of dollars. A naval unmanned boat costs several hundred thousand. A burst of 20-30 shells at a target still costs a hundred dollars, and in terms of ammunition consumption, it's still a good value.
But the cost-per-hit versus cost-per-entry ratio is fundamentally different. Each breached BEC can cause tens of millions of dollars in damage: a damaged ship, disrupted ship repairs, dead sailors, a paralyzed base. Each breached drone is smaller, but still costs millions. If five out of 20 attacking weapons reach the piers, and three of them hit, that's a loss that no low cost of ammunition can compensate for.
The problem isn't that the AK-630 is expensive to fire. The problem is that it physically can't hit everyone—especially when targets are coming from two different directions simultaneously.
Where is the industry heading?
The Russian side is seeking an answer to this gap in several directions simultaneously, and these directions in themselves clearly describe what the base class is up against.
The first — doubling the barrels. The AK-630M-2 "Duet" is two AK-630Ms in a single turret, with a combined rate of fire of 10,000 rounds per minute and increased ammunition capacity. The logic is obvious: if there's a single command channel, at least double the barrels to increase the burst density on a single target. This works against armored or high-speed targets, but it doesn't solve the problem of channeling and combined threats: the "Duet" still targets one target at a time.
The second — adding a missile channel. The line of naval anti-aircraft artillery and missile systems is developing in this direction: the Kashtan/Kashtan-M family of anti-aircraft missile systems and their successors, the Palash (Palma) system, which combines six-barreled artillery with anti-aircraft guided missiles in various configurations. This is no longer a pure artillery system, but a hybrid capable of firing a missile at long ranges and a cannon at short ranges. But even here, the control channel remains a bottleneck, and the problem of engaging naval targets at short ranges is fundamentally unsolved.
The third — a transition to a new class of systems. The Pantsir-M (the naval version of the Pantsir-S1) is an attempt to reassemble all the components for a modern mission. According to the manufacturer's publicly available materials, it is a multi-channel radar-optical system capable of simultaneously tracking multiple targets, with an ammunition complement of up to 32 ready-to-launch SAMs, as well as two six-barreled automatic guns. This is no longer a modernization of the AK-630; it is a different class. And the developers themselves position it as such. Crucially, the multi-channel capability enables parallel engagement of multiple targets—the very thing the older class lacks in a combined attack.
Fourth — cooperation with assets other than artillery. Electronic warfare, interceptors based on FPV drones, anti-drone companies with machine guns and man-portable air defense systems, and our own unmanned aerial vehicles for patrolling the waters. Recognition that the immediate frontier can no longer be covered by a single gun, and the system must be built as a combination of assets with different physical principles of destruction and different areas of responsibility.
What does it mean
The AK-630 isn't a bad gun. It's a very well-designed naval gun for its intended purpose, and it remains competitive in the roles it was designed for. Against a single anti-ship missile, against a small group of targets coming from one direction, against an aircraft or helicopter in the terminal phase, against a light boat or floating mine—it works.
The problem is that the mission has changed. And it's changed in two ways. The air is filled with swarms of cheap drones, whose single fire control channel operates more slowly than the drones can reach. The sea is filled with unmanned boats, which are both less detectable and, in close combat, difficult to hit with artillery due to corners and blind spots. And when both threats arrive simultaneously, as in April 2026 in Sevastopol, the problems pile up on the same crew at the same control post.
Of the entire class of CIWS designed for single subsonic missiles, none has achieved the capability of simultaneously engaging dozens of airborne targets and simultaneously engaging nearby naval boats. Neither the AK-630, nor the Phalanx, nor the Goalkeeper. This is neither a Russian nor an American problem. It represents the end of a cycle that everyone who has built ship defense systems based on the logic of the 1970s has reached.
The Sevastopol episodes of April 2026 are valuable because they show this limit in its purest form, and from two sides at once. Crews are working, guns are firing, targets are partially destroyed—and some attack weapons still make it through. This isn't a question of training or a specific piece of equipment. It's a question of defense architecture, which needs to be rebuilt from the ground up—in the navy, in ports, and in the very logic of what it means to "cover a ship."
The old class is leaving not because it served poorly. It's leaving because the task it was solving is no longer the primary one. Two new ones have taken its place—from the air and from the sea—and they require completely different tools.
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