Although it may seem confusing, MRSI is actually a very simple concept. Once again, MRSI works by utilizing the different trajectories and flight times of the projectiles to hit the target at the same time, even though the shells themselves were fired at different times. In order to further our understanding, take a look at the image below.

Source[commons.wikimedia.org]

As we can see, this artillery system can hit the target using different trajectories. The higher trajectories are longer and will take more time to fly to the target, and conversely the lower trajectories will take less time. Therefore, we can fire our first shots on the higher trajectories first, and then work our way down to the lower trajectories in the follow up shots. Assuming we've timed our shots well, all of the shells we have fired will hit the target at the same time.

However, we have to create these different trajectories in order for MRSI to work. That's where the propellant charges come in. Typically, different levels of charges are used to fire at targets at different ranges since using more charges means the projectile will fire further. However, that also means that, provided there is an overlap between the effective firing ranges of the different charges, we can hit inside that overlap with multiple different trajectories.

So to summarize, we use different charge levels to create different trajectories, and fire our ordnance on those trajectories at specific times so they all reach the target at the same time. This is, in essence, how MRSI works.

In order to carry out MRSI, there are a few prerequisites that we need. The artillery system itself needs to have multiple levels of propellant charges, and must reload quickly enough to fire the follow up shots on time. Additionally, we have to position ourselves in a spot that places the target in an overlap between the effective firing ranges of different charges. Finally, we need proficiency in operating the artillery computer or, if we really want to, how to calculate firing solutions manually.

In this guide, we will be using the Mk6 mortar system which is fast firing and has wide overlaps. Keep in mind, however, that assuming the artillery system meets all of the prerequisites, it should be able to do MRSI as well (like the M4 Scorcher or M5 MLRS). Additionally, to keep things simple, we will just be using the artillery computer for this. However, once again, all of these concepts can be translated and manually calculated as well.

The last thing we need is a target within an overlap that was mentioned before. Before we do that, however, we need to know what an overlap is and how to find them in the first place. Any artillery system will have a minimum and maximum range for a given propellant charge. Take a look at this screenshot of the artillery computer UI.


We will first go through all of the features of this UI. If we are already familiar with the UI, feel free to skip reading this section. The main thing we need to know is our mode, minimum and maximum range, and ETA.

In section A we have the controls of the artillery computer. From here, we can see what artillery system we are using (Mk6 Mortar), what mode or charge it is in (semi/close), and what type of ordnance we are firing (HE Mortar Shells).

In section B, we can see some general information about the map. Some of the information in this section will change based off of where we are hovering our mouse. We can see information such as the grid reference of our mouse, distance from us to our mouse, minimum and maximum range of the mortar, bearing, and altitude.

In section C, we can see information on a target that we click on. The main thing we want to pay attention to is the ETA, as we will use this information to time our shots later. The ETA is how many seconds before the shell is expected to reach the target.

Section D and E mark a visual reference for the minimum and maximum range on the map. 2 concentric circles are drawn representing this minimum and maximum range, making it easy to quickly judge whether we can fire at a target or not. Keep in mind that this is not a strict limit, and there are times where you cannot fire inside the max range and also times where you can fire outside of the max range, most likely due to differences in altitude.

As we can see, we are currently on the semi/close mode, which has a minimum range of 34 meters and maximum range of 499 meters. However, if we switch to semi/medium we will have a different minimum and maximum range.


Now, due to the change in propellant charge (medium instead of close), we have a minimum range of 139 meters, and a maximum range of almost 2km. We can now see that the minimum range of the medium charge is below the maximum range of the close charge, giving us a 360 meter overlap where we can fire both close charged and medium charged mortar shells.

This gives us a nice wide overlap to work with, but we do not have to stop at 2. We can continue adding higher and higher charges, provided that the minimum range of the highest charge is within the maximum range of the lowest charge. In the case of the Mk6, the minimum range of the semi/far charge is 284 meters, putting it well inside the 499 meter maximum range of the semi/close charge. This tightens our overlap though, to just 215 meters.

Collating all of this information, we can put together a table that looks like this:


Making a reference table like this is not necessary, but can help during practice or in a dynamic environment to quickly determine if a target is within an overlap.

Now that we understand how MRSI works, and we have all the tools we need to find out if we can use MRSI on a target, the only thing left to do is to put these theories into practice. Once again, we need to either pick a target within an overlap, or maneuver our mortar that places the target within an overlap. Our situation is laid out below.


The target is an armed vehicle and an attached fireteam. The fireteam is out in the open, and we can immobilize the vehicle using our mortar shells as well. However, there is a lot of cover the infantry could move to, and the vehicle could quickly get away. Therefore, we must put as much ordnance on the target as possible in the smallest amount of time to maximize the effect we have.


Looking at the map we can see even more information about the target. The distance to the target is about 380 meters, putting it in a triple overlap with all 3 modes. Additionally, we can see that on semi/far mode the ETA is about 40 seconds. Before we fire though, we need to switch to the other modes in the overlap and check the ETA for those as well.



As we can see, the semi/medium mode has an ETA of 28 seconds, and the semi/close mode has an ETA of just 13 seconds. These differences in flight times will allow us to time our shots so they all land at the same time. Once again, we fire the higher charges first since they have the longer flight times, and work our way down to the lower charges, so let's go back to semi/far and fire the first shot.


Once we fire, an ETA XXs will pop up, tracking our shell's flight path and dynamically updating the ETA. DO NOT EXIT THE ARTILLERY COMPUTER OR THIS INDICATOR WILL DISAPPEAR. The semi/medium mode has an ETA of 28 seconds, so we wait until the indicator on our first shell says 28 seconds to fire the semi/medium charged shell.


Now we have 2 shells with the same ETA. Based on this, we have been able to successfully carry out MRSI. However, we do have one more charge we can fire at the target, so let's finish up with that.


Now 3 shots are flying towards the target all timed to land simultaneously, and all fired from the same mortar. This is essentially how MRSI is done, and we can now examine the results.



If the shells landed too close to each other to see all 3 mortar impacts, that's because we did a good job. Here is a picture after the fact showing 3 mortar craters.


Additionally, you can see that we have neutralized all the surrounding infantry and immobilized the vehicle, giving friendly forces a much easier time carrying out their objectives in this area. By using MRSI, we can focus our firepower to hit the target very hard in a very short amount of time, effectively maximizing devastation in the key moments while the enemy is unaware.

As with any tactic, there are advantages and disadvantages to MRSI. The biggest advantage that MRSI has is that it maximizes firepower on the target in a very short amount of time. Historically, it was found that the most amount of casualties inflicted by an artillery barrage were within the first few seconds of the barrage landing. After that, the enemies would have taken cover or moved away, making follow up shots ineffective. Therefore, by making all the shells hit the target at the same time, the casualties are maximized.

There is, however, one big disadvantage. Due to the nature of how MRSI works, the tactic is very inflexible, and really only useful against preplanned, static targets. Part of the reason is because MRSI takes the longest possible flight time to hit the target. As we saw in the example, even though the semi/close charge took just 13 seconds to hit the target, we had to wait the full 40 seconds of the semi/far shell to hit the target. If the target was moving, it would be nearly impossible to predict the movements of it out to 40 seconds. Additionally, we also have a very limited range to work with. In the example, we had to place the mortar within 285 and 500 meters, just 215 meters of range that we can operate in. These issues can be mitigated somewhat by using only closer charges which will decrease the overall flight time and increase the size of the overlap, but that also lowers the effectiveness of MRSI and really is not how it should be used.

There are also other ways to increase our effectiveness when using MRSI. The example was a very simple and basic usage of MRSI. All the shots we fired landed in the same place at the same time. However, we could fire at different targets. This would spread out the damage, and if used on guard posts and other known positions, could be very devastating. Additionally, we do not have to make our shots land exactly simultaneously. If we are willing to spread out the time frame to even just a few seconds, on faster firing artillery systems like the mortar we could potentially send many more shells but have them land at relatively the same time, further multiplying the amount of firepower we can put on the target.

We also did not utilize other types of shells. Say for example we have already devastated the enemy with an opening barrage of HE. We could then switch to smoke shells and, using MRSI, lay down a huge smokescreen to cover an approaching assault. If we wanted to, we could even have the smokescreen land at the exact time our HE shells land, simultaneously devastating the enemy and blinding them at the same time.

To summarize, when using MRSI, it is most effective against static and unaware targets. Use it as the opening strike of an assault to maximize casualties and immobilize vehicles, then use the mortars to suppress the area with regular fire and smokescreens to cover the attacking force. Pairing this tactic with multiple artillery systems can devastate even the most defended of hardpoints and make an assault a much less costly proposition.

While MRSI is rather inflexible to changes in a combat situation, it is still a useful tool and can be very effective if utilized properly. The tactic is best used when the most amount of firepower is required within the shortest amount of time.

Thank you for reading my guide. If you have any questions or comments, please write them down below.