Do we need light mortars?

The Soviet Union abandoned its company mortars halfway through the war, deeming them too weak and short-range for the contemporary combat conditions. But in NATO their 60mm counterparts blossomed and flourished. Now our army is facing these weapons again, and the estimates of their effectiveness vary greatly - from "worthless garbage" to "god of war". At the same time the real assessment of their effectiveness is nowhere to be found. Recently I asked people to tell me if they have ever used 60 mm mortars and what they think about them, and I read the information on their use in Ukraine and tried to select the main points. The result was this article.
I will start with a couple of 60mm mortars to give an idea of their technical capabilities. The most distinctive is the American M224 LWCMS (Lightweight Company Mortar System). As the name suggests, it is used as a company fire support weapon, usually one squad with 2 mortars, but in the Marines with 3. It consists of a M225 barrel, M170 bipod, M7A1 base plate weighing 4.4 kg for firing like a classic mortar, or a small M8 of 1.6 kg for hand-held firing (a common practice in Afghanistan), and M64A1 or M67 sights. The mortar weighs 21 kg overall or a little over 12 kg when firing in handheld mode. There is also a lighter modification, M224A1, which started to enter the army in 2011. It was lightened by 4 kg with light composite barrel. Negative side effect is abandonment of cooling ribs, which leads to the rapid barrel deterioration under severe firing. And so, if you want, you can get up to 30 rpm in the first minute, and in actual combat 15-20 rpm. The ultimate range is as much as 3490 m, which is quite comparable with the 82mm BM-37, which are not so rare. The standard 60 mm high-explosive fragmentation bombs are M888, M720 and M720A1, the training type M769, various smoke and illumination bombs. Initial velocity depending on the charge varies from 65 to 241 m/s. Now the improved fragmentation M1061 with 256g PBXN-110 explosives began to arrive, comparable in power with the old 81mm bombs and flying as much as 4500 m. It can be equipped with several types of fuses, including timer-detonated and multi-mode, with which it can work as a purely fragmentation bomb as well as a high-explosive bomb.

The Polish LMP-2017 (Lekki Moździerz Piechoty - Light Infantry Mortar) is a rare guest, but very distinctive. The Poles began working on their 60mm in 1991, almost immediately after leaving the WTO, and ended up with the LM-60 to arm platoons and companies. Its size was severely limited by the size of the troop compartment of their vehicles, so it ended up being relatively short. The idea was developed in the LMP-2017, the mortar became even smaller and lighter, only 6.6 kg, can be fired only with arm support. Various lightweight materials were widely used - titanium, plastic, aluminum alloys. The range of fire of Polish bomb O-LM60 Pluton-1 is only 1100 m, but it has a solid mass of 2 kg against the standard American M888/M720's 1.67 kg. There is a long-range O-LM60H, which flies at 1300 m, and an illuminating S-LM60. The fragmentation mines are equipped with a ZGM fuse, have 1500 ready fragments and 166 m/s initial velocity (175 for O-LM60H). Interesting fact: with the listed caliber of 60mm, the actual caliber of the LMP is 59.4mm, while the others have 60.7. But it was decided to switch to NATO ammunition, mortars will be given 60.7 mm barrels as the old ones are worn out. For greater efficiency, a long-range (like, 1500 m) version LMP-2017M weighing 19 kg was developed, equipped with a digital sight. Our guys sometimes write that Polish mines are inaudible because of the special plummet device, but everything is somewhat simpler - they have a very low muzzle velocity.

And now we can move on to the main course, namely the collected results of the use of light mortars in Ukraine.

P.S. The italicized opinions below are written by the author. It is as subjective as possible and is not a reference.

Where and who uses them

In most cases the light mortar is a weapon of sabotage and reconnaissance groups, mobile detachments, and is often mounted on some kind of vehicle. In some places it was actively used by regular infantry (but most likely someone acted in the same formation as it). In conditions of a stable frontline it is fired at the front, during firefights soldiers may not notice that mortars are firing at them. It can operate from trenches without much preparation of the position. SRG and mobile groups use it both at the front and during incursions into the rear. There was a case where they captured a pickup truck of armored vehicle hunters where RPGs and ATGMs were stacked in the back, and in the cabin together with the men they pushed a 60-mm mortar with two dozen mines - the size allows. In urban areas on a weak charge the light mortar confidently hits over the buildings, especially if they are not 9-storey buildings, not allowing the enemy to relax in all sorts of coutyards.

Alternative uses

Because of its small weight, 60-mm mines can easily be bolted to a quadrocopter, which is the best option for such equipment - VOGs are weak, and 82-mm mines are heavy. Accurate release confidently hits unarmored equipment, some models of mines are able to pierce the roof of poorly protected armored vehicles.

Effectiveness of firing

The situation here is ambiguous. On the one hand, a lot of shrapnel gives a high hit density, wounding fighters. Explosion pressure effect is small, but in the absence of reliable dugouts, pillboxes, overlapping trenches, armored vehicles can scatter tents and shelters, break the thin armor in a direct hit. One individual wrote about powerful mines, but clearly 60-mm, and quite weak, with little shrapnel. In general, the main casualties from these mortars come from shrapnel. The anti-shrapnel elements of the body armor hold up to the hits with confidence. But, again, the new shells have a huge kill field with lots of small shrapnel, wounding legs, arms, and face.

The 60mm mortars with full mounts show good accuracy and consistency, allowing them to hit trenches or single vehicles.

Use by the Allied forces

There were isolated cases, no details. At the time of the active offensive they were not the most frequent guests, and there were enough Ukrainian M60-16 Kammertons.

Advantages and similar weapons we have

Its low weight, ease of position preparation, high rate of fire, and steep trajectory make the 60 mm mortar a serious platoon-company-level weapon. The equivalent of such a motorized rifle company qualitative enhancement weapon in our arsenal is the AGS, which is much heavier, has less range, power, and is intended primarily for firing at targets in the line of sight. In principle, AGS is a different class of weapon and the comparison with a mortar is incorrect. The 82mm is excessive in mass, and the old mines are quite comparable in power to the modern Western 60mm type M1061 at a much greater mass. Compared to the old and commonly used BM-37, the M224 is even superior in range.

A separate note is the low-noise nature of the shot, due to the weak charge and low muzzle velocity (which gives rise, again, to myths about special silent Polish mortars). Because of that the position is almost impossible to detect in combat due to other noises, and it is difficult to find it using a counter-battery radar like the Aistenok and instantly hit it with artillery because of the small number of such radios and the difficulty of aiming the guns in a short time while the light mortar remains in position.

Again, here we can consider as an analogue the 82 mm Gall 2B25, the gases of which are locked in the tailpiece of the ZVO35 mine (a similar principle was used in the PSS gun). Because of this, the latter has a low range of 1200 m and a large size. Yes, it should be noted that 13 kg weight is less than that of NATO models with full mount, but because of the size and weight of the mines (no exact information) the detachment can not carry much. All the same, this is a weapon of special units, not ordinary infantry, they have other requirements.

Conclusions

Now it is time to summarize. Light mortars are needed, but for light infantry units, trench warfare, saboteurs, i.e. those who often carry all their weapons on their backs. Such troops have almost disappeared in our time, but now they are returning to them again, forming both at the front and in the rear. Combined with the drone, the 60-mm mine's ability to support a platoon-company is quite enough. It is quite suitable for the defense of fortifications in the Kursk and Belgorod regions, holding the front in Zaporozhye and near Svatovo-Kreminna. But there are problems here, such as the production of non-standard ammunition, the training of a huge number of crews, the mass production of mortars itself, so even if they want to do it now, it will not work quickly.

The situation is more interesting with motorized rifle units, which must work in conjunction with armored vehicles. Often, because of the lack of artillery, they began to use tanks and BMP-3s for firing from closed firing positions. Standard 120-mm mortars are not enough, also because of the weak mobility and high vulnerability of the complex based on the unarmored Ural. It takes too long to roll out and roll back in, you can get hit back. In the 00's they were going to give each battalion up to 9 120mm SPGs, similar to the Nona, but it all died out because of the price. Companies were left without their weapons for firing from an enclosed position in any case. But here is an interesting specimen - 82mm self-propelled mortar system 2K32 Deva. It is armed with the 2B24. This beast can shoot 3-O-26 mines, approaching 120-mm in terms of power, for up to 6 km, which means it is analogous to the Western MAPAMs. Also interesting are options to install automatic Vasilok or 57-mm LShO on a self-propelled chassis. Cheap, mass-productable and simple. At the same time such a self-propelled mortar in large-scale production can displace 60-mm variants.

Alexei Borzenkov

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Original article © A. Borzenkov