Monstrum Side Saddle 12 Gauge Shotgun Shell Holder | Compatible with Maverick 88/Mossberg 500/590/Shockwave Series Shotguns

Ordered this item for, my recent purchase of my Mossberg Maverick 88. Bought this as the combo package with the two barrels, and wanted to stay at a budget point. With that said, I wanted to accessorize it, but not spend a ton of money. I bought the Monstrum side saddle, and didn't have any preconceived notions as to how good it was. When it arrived, I was pleasantly surprised at how solid it was and how nicely built. I honestly just expected a piece of plastic. It has a great metal backing plate. It was also designed perfectly, and lined up exactly with the holes for installation. Easy to read and understand instructions made installation a breeze. After a day at the range, it worked perfectly. Upon cleaning the firearm post shooting, I did realize it was a little loose. That did not surprise me, as the force of 100 rounds through a 12 ga shotgun would knock anything loose. I also never used any loctite on installation. ( hindsight) When I tried to tighten it up, I think I added a little too much force, and probably stripped one of the mounting screws....my fault, not the product. I reached out to Monstrum, to buy replacement screw/pin, so I could remedy this issue. The gentleman asked for a copy of my order ( gave the Amazon screenshot picture) and my address. He never asked for any kind of payment at all. Two days later the parts showed up, and perfect delivery. Outstanding customer service and standing behind their products. I wish all companies were this good. Highly recommend their products.

This side saddle fit my Mossberg 500 12g perfectly as advertised. Because my gun's forearm is the long version (which helps with my short stature...), I cut the front shell holder off and drilled a new rear mounting hole. The front end has 2 mounting holes, and I used the "wrong one" to move the whole shell holder back a little more. I'm very happy with it, and I used it in a defensive shotgun course last weekend. I am a certified shotgun instructor and FFL dealer. This is good equipment. The shell tension is just right, and you can place shells brass up or down without them falling out.

Honestly bought another one just for the screws. First one is great. Sits well on my shotgun. But I guess I didnt tighten a screw down enough so it fell out

Looks good, seems to hold shells ok. The screw holes don't line up to fit my 500 3-in-1. When installed as directed the forend does not slide back all the way. I was able to get it to fit by moving it backwards using the forward most top screw hole. I removed the rubber shell holder then I marked and drilled a hole where the pin is. I installed the screw and screwed it to the new threaded pin, reattached the rubber shell holder and pushed the pin into the pin hole. Then installed the washer and reverse side bolt.

This product is good, but like so many of these marketed for a 500, it doesn't fit my 500 with the stock wood fore-end. All of these manufacturers must assume we all run the 'tactical' versions of these shotguns and don't bother testing the classic 500 wood fore-ends. Very disappointing. The mounting plate does line up with the fasteners of the 500. The issue is that the shell slot closest to the muzzle blocks the action of the pump. And it does so enough that you can't cycle the weapon. It is easy enough to cut off, but having to mod a $25 accessory is super annoying. To be fair, the product itself is not bad. But the listing says it will fit a 500. It doesn't fit ALL 500's and they should say so. 🤬🤬🤬

First off I just want to say that this saddle fits perfectly on my Maverick 88 and since its the poverty pony version of the Mossberg 500 I can definitely say that this saddle will work for that as well. But this side saddle has a very major flaw and it would be the fact that there's solid plastic connecting the edges of the sleeves that makes it so that the far left and right sleeves work smoothly since they can stretch out but the middle four simply cannot stretch out as needed. I simply used a sawzall blade to cut away at these plastic connections and then sanded the area down so it looked half decent in appearance, and this type of work that I have to do just so I can get a smooth feeling of pulling out shells from the middle four sleeves is unfortunately enough to lose two stars in its favor. If I had to depend on this side saddle on a life or death reload and I got hung up on a stuck shell, then that is simply unacceptable too.

Taking the ejector screw (slotted flat head flat head) out of the inside of the gun was harder than implied. The rest was actually pretty simple. The replacement ejector screw (0.25" longer) had a Phillips cross. It should have been a hex to fit the larger allen wrench included in the kit. The simple instructions on the side of the box should be replaced by an expanded set of instructions on a piece of paper sent inside the box. There would be room for details like TIGHTEN the new ejector screw and get a 9/32" socket to tighten down the nut holding the shell holder to the gun and be sure to put one of the included washers under the nut. I was particularly happy when I wrote MONSTRUM for info about complaints on Amazon in the 1-star area. I received feedback that those were based on an early release addressed a while back. The factory rep (Gerald - GOOD guy!) was correct. This works like a champ and when installed with a full 6-shell load on my Mossberg 500 Tactical Breacher makes a bad-boy gun look like something Satin might carry.

The shells either fit or they fall out. You have to stack them top to bottom instead of how it’s intended to work. The slick plastic doesn’t work. Maybe add ridges to the inside of the shell holder for more grip.