Monstrum Laser Sight System with Picatinny Mount for Mossberg 500/590/835/930/Shockwave Series Shotguns

The Monstrum Laser Sight System is just as advertised and shown. The laser is well packaged and easy to install. The supplied mounting screws fit my Mossberg 590 perfectly and the green laser is bright, especially inside or in dim light. I will be using my 590 for home protection so this fit my need perfectly. I also like the rail system and mounted a pistol light on it since I will be firing it from the hip and not looking down the barrel to aim. The combination works fine and the light works great for inside of a home or around the yard. I highly recommend the Monstrum Laser Sight System...especially for a Mossberg 590 where it is intended to be fired from the hip.

Quality and works great

Parasitic battery drain: I must be one of the unlucky ones. While I see several outstanding reviews, there area few 1 star reviews and I will be adding mine to that category. There is some type of occult parasitic battery drain that results in a dead battery when the gun is put in storage. Like others, the 1st time it happended, I thought it must be my fault? I must have left it on. So second time I was very careful to be certain it was off, after testing it, and yet it still drained in about 2-3 weeks. I then (yet again) put in new batteries, confirmed they worked, but then removed and reinstalled the batteries without testing them. They lasted for months and months and were working fine when I did actually need to take the weapon from the safe and use it. Once tested, however, they too failed (drained out) in 2-3 weeks.Seems the only soultion is to NOT test the batteries, or insert them - but that just means the weapon is NOT ready at a moments notice - which OBTW - is the reason one keeps a weapon.

Fits my Shockwave 12gauge perfectly. Easy to install. Easy to zero laser. Ample rail space for tactical flashlight.

The picatinny mount with the laser seems to work fine. However, of interest to others may be that I have a Mossberg 505 410ga and this mount fit perfectly. Monstrum does not list that model but fear not, it fits. Actually, I suspect it would fit any of the Mossberg 500 series models but I can't prove that. The only real issue was with the battery instructions. The instruction card arrow points to what would be the back of the laser unit and seems to indicate you have to remove the on/off switch unit. You do not. The actual battery compartment is located on the front of the unit, next to the laser lens, and the two CR 1/3 N batteries fit perfectly in that compartment. Just install the batteries negative (-) end first.

It works and fits well. All needed tools included and even batteries. Laser tag is bright and was easy to adjust. My only knock is I wish the laser was on the right instead of the left. With the left placement, the laser can easily be obstructed when your left hand is on the shotgun forend. When racking the slide of my .410, I must be aware of my left hand placement to avoid blocking the laser.

Mounted on a 510 Mossberg Mini Bantam 410 ga.Fits exactly matching existing 4 holes on receiver.Zero'd laser which originally was bouncing off the barrel fresh out of the box.After zero'ing, it matches nicely a boresight laser aimed at 25 yards.The laser dot size is not that of a $100-300 laser only. But it's way good enough for short range use cases.The mount screws are high quality, the pic rail itself is high quality, too, not cheezy at all.The only thing I worry about is the laser zero'ing coming off after some shots, but then again 410 is no big recoil platform.Definitely recommended vs a plain pic rail, the laser was worth the extra price.

At first, I was very impressed, while zeroing it with a shell boresighter in my house (gun unloaded, OF COURSE!). I liked how bright the dot was inside my house, either in complete darkness or fully lit rooms. Then I went to the range, and when I first turned it on, I thought the batteries may be dead. They weren't. Unless the dot was on something dark in the shadows, it is completely invisible in sunlight. That makes it completely useless in the daytime.The next problem, which I discovered immediately and confirmed later at the range, is that the center groove on top of the base is not nearly deep enough. It completely obscures the big dot front sight on my Mossberg Shockwave 20 ga, so that also make the weapon reliant on only the laser, since the laser makes the front sight become completely useless.What it boils down to is that this is a nice accessory for home defense only. It simply does not work in sunlight, and it makes aiming with sights impossible. I needed something to take camping, which will involve being in sunlight, so I have wasted my money on this and will probably remove it. I should have returned it while it was still eligible. Lesson learned - do your research FULLY in advance.