Monstrum Red Laser Sight System with Picatinny Mount

Mossberg 500/590/835/930/Shockwave Series Shotguns

If you own a Mossberg 500/590/835/930/Shockwave Series shotgun for home defense, lasers are invaluable.

If you have read the article on the Mossberg 590 Night Stick (THE SHORT ANSWER TO HOME (OR PERSONAL) DEFENSE – Part 1 and THE SHORT ANSWER TO HOME (OR PERSONAL) DEFENSE – PART 2), you would know that when I set up the Mossberg 590 Night Stick with a green laser that sits atop a Mossberg Picatinny rail. While I like the setup, the green laser unit sits too high for my liking and is bulkier than I prefer. A search ensued for a better, more compact laser unit.

I have reviewed red, green, and red/green laser units that would fit pistols and rifles until the cows came home, but I felt that none of them would hold up to the recoil of a 12-gauge…even one that runs “mini” shells. Then, I came across the Monstrum Red Laser Sight System with Picatinny Mount Mossberg 500/590/835/930/Shockwave Series Shotguns at There was only one review on it, which did not say much about the product, but I liked the unit and decided to give it a try and report the results.

The Monstrum Red Laser Sight System with Picatinny Mount Mossberg 500/590/835/930/Shockwave Series Shotguns can be quickly installed atop any of the listed shotguns with pre-drilled mounting holes. However, it is not compatible with the following for the reasons shown:

  • Pre-1997 Mossberg shotguns | Requires 6x48TPI screws not included
  • Mossberg shotguns without pre-drilled and tapped receivers | Requires drilling and tapping receiver
  • Mossberg Maverick 88 | Requires drilling and tapping receiver
  • Mossberg shotguns with Crimson Trace LS250 installed | Requires M4-.70 x 12 screws not included
  • Mossberg 930 | Requires modifications
  • Mossberg 500 Flex | Requires modifications

That’s not saying that it will not work on these shotguns just that these shotguns require modifications for it to work.

You will note that this unit incorporates a red laser rather than a green laser. I like a green laser, especially outdoors, but a red laser is more than adequate for indoor, CQB use. Equipped with a powerful 5-milliwatt laser module, the laser sight can be used in a variety of lighting conditions out to a distance of 50+ yards. In my home environment, that distance is a lot less.

As previously stated, the unit was to replace the laser sight and Picatinny rail already mounting on a Mossberg 590 Night Stick.

Mossberg Night Stick

Installation took the time needed to remove the existing rail and mounting the Monstrum unit (Mounting screws are provided). The mounting holes lined up perfectly with those on top of the Night Stick but the mounting screws used to mount the previous unit could not be re-used. The Picatinny rail mount allows for the mounting of Picatinny standard scopes, red dots, other optics, or my custom-made, individual Jack Link’s Beef Snack Stick holder.

The 5-milliwatt laser module is powered by 3 AG3/LR41 batteries (included) that install from the front of the unit with the help of a provided wrench. The battery cap seems to seal the battery compartment well. (Author’s Note: I keep a second ‘backup’ set in the firearm’s tote bag.) The vendor information at the Amazon website states: Batteries: 3 Lithium-ion batteries required. (included). However, the unit came with 3 AG3/LR41 1.5V Alkaline Cells. The batteries were installed prior to installing the unit on the firearm. The 3AG/LR41 batteries are very small and it took several attempts to install the first battery in the proper orientation; A set of tweezers to install the first battery cured that problem and the remaining two batteries were installed with no issue.  

The laser diode is well within the unit and no protective cover is provided.

I cannot estimate the battery life yet and there is no automatic shut-off feature with this unit (read A Word About Batteries at the end of this article).

The laser unit lays low on the left front of the rail, the finish of the mount and laser closely matches the finish on the Night Stick, and is unobtrusive. A rear push-button, with a solid-feeling click, provides the means to turn the laser on and off; No cable is provided for remote operation. I found that I could quickly turn the laser on with my support hand as the support hand was heading to the pump handle, and is very close to the pump handle hand when the hand is on the handle. (Author’s Note: Here is some tongue-twister help to read what you just read while reading; “When I was down in Arkansas, I saw a saw that could out saw any saw that I saw. If you are down in Arkansas and see a saw that can out saw the saw I saw, I would like to see your saw saw.”)

Easy Access On/Off Switch

Adjustments are available for elevation and azimuth (windage) and a very sloppy fitting adjustment wrench is provided.

The rail also incorporates a sight groove that allows you to use the front sight. I, however, opted to cover the rail with a cover to protect the rail and to keep me from mounting anything silly on it. I have no intention of placing the grip of this firearm anywhere near my face, and that’s what the laser keeps me from doing. The Mossberg 590 Night Stick is a point n’ shoot interface.

Protective Rail Cover

When installing the mounting screws, which will take a separate Torx wrench to install, use  dab of blue Loktite and do not over-tighten…just snug will do.

I like using a bore-sighting tool when setting up a scope, reflex sight, or laser rather than wasting a load of ammunition trying to get one zeroed. With the bore sighting kit that I have, I can simply match the laser sight’s beam to the same spot as the bore sight beam. While this may not be accurate enough for a rifle, it is more than accurate enough for a shotgun at CQB distance even when shooting slugs.

Sighting In

I measured the distance from the hallway in my house to the kitchen door, which is approximately twenty-five feet, and that was my zero point. Note that once adjusted for elevation and windage, I dropped a dot of blue Loctite on the threads of the adjustment screws to help ensure that they do not shift under recoil. Periodic check will be made during and after range sessions.

The Mossberg Night Stick is a sleek looking legal 12-Gauge short firearm and the Monstrum Red Laser Sight System with Picatinny Mount does not take away from the sleek look. For indoor CQB use, I think the setup is excellent and a win-win combination.

Previously Mounted Unit
Monstrum Red Laser Sight System

A Word About Batteries

The unit came with three AG3/LR41 batteries of unknown origin and unknown expiration date. I must assume that I will be replacing them soon. According to resources, these are product compatible models:

LR41/AG3 1.5V, LR41H, SR41, SR41W, SR41SW, SR415W, TR41SW, D384/392, 392, 392A, 392BP, V392, GP392, D392, 192, GP192, LR4192, R 392/2, 384, D384, SP384, V384, R384/10, G3, G3A, L736C, L736F, SR736, SR736PW, SR736, SR736SW, S736E, SR736W, SB-A1/D1, A63, 325, 280-18, 247, 10 L 125/D, and others.

There is a plethora of manufacturers for these batteries (primarily The People’s Republic of China). It will take some shopping to determine which battery you want to use. I read one review from a laser user that went through three (the number needed to power the Monstrum Red Laser Sight System) of the Duracell 384/392 silver oxide batteries within 45 minutes of use. While batteries can be ordered online, I would recommend that you purchase them locally so that you can check expiration dates rather than taking a chance on them from on-line vendors.

I’ll leave the three AG3/LR41 batteries of unknown origin and unknown expiration date in the laser until I get it zeroed, then replace them with the Murata 392/384 SR41/W/SW Battery 1.55V Silver Oxide Watch Button Cell batteries, and keep some spares handy.

According to my research, an SR battery can store almost twice as much energy as an alkaline battery. They provide a flat discharge, meaning release energy more evenly compared to alkaline batteries, which can shift more dramatically from releasing lots of energy at first to less and less as time goes on. That makes silver oxide batteries great for powering more delicate electronics that require a steadier flow of power. On top of that, they often have a shelf life of around ten years.

In a real-life encounter, 45 minutes is an extremely long time. However, time at the range while using the laser can be longer than 45 minutes. If a laser is mounted on your favorite home/personal defense firearm, it would behoove you to check the batteries often.

In Closing

Using optics on a firearm to enhance shoot-ability cannot be argued and have many benefits. The downside is that optics must be maintained to ensure that they work when they are needed, and they must be properly sighted to ensure the accuracy that you need.

Although I mounted the Monstrum Red Laser Sight System with Picatinny Mount Mossberg 500/590/835/930/Shockwave Series Shotguns on the Mossberg 590 Night Stick, the unit can be mounted on any full-size, compatible shotgun. I find the red laser to be more than adequate for indoor use and allows quick target acquisition when I need it.


About Taurian

Taurian is a U.S. Army veteran and former LEO and Defensive Tactics Instructor. Taurian also has over fifty years of experience as a Technical Writer and Training Program Developer. After leaving home at the age of ten without any shoes, Taurian continues on with many years devoted to the keeping and bearing of arms.

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