Monstrum Side Saddle Shell Holder with Picatinny Rail Mount for Mossberg 500/590/Shockwave Series Shotguns

Great holder! Easy install. Firm grip on shells. Looks great.

Great little add on to the shockwave lazer style. You have to mount on the left side because of the laser. But doesn’t throw the balance off, when Pummeling targets. Great little piece.

Amazingly, this product does exactly what it says it will do. First of all, let me comment on the ease of installation. Four long screws take the place of the filler screws on the top of the receiver. This item is in 2 pieces. The Pic rail is one part and the shell holder the second part. The shell holder in held in place by the 4 screws that hold the Pic rail to the receiver. A very secure mount. One thing that is different than the picture of the item is that the bevels are actually beveled down. Shown in the ad the bevels are up. I wondered about that but the one I received had the bevels on the bottom side. As they should be. Love the item and although I would have liked to see it less expensive, it turned out to be well worth the money. I have pictured it mounted on my 590 but they make them for a bunch of tactical shotguns.

I have done business with them before, and I will do business with them again absolutely excellent products in their customer service this second to none I would highly recommend purchasing their products

The Picatinny Rail and Shell Holder are good quality in my opinion and fit my Maverick 88 perfectly. I have an older model that was not drilled and tapped for 8x40 screws that are included with the product so I had to get that done. What I did run into was the included 8x40 torque Head screws are about 3/8 of an inch long (threaded part) and if I only installed the Picatinny Rail the screws went almost the entire depth of the threaded mounting holes in my Maverick however when the Shell Holder is mounted under the Picatinny Rail the screws are about an 1/8 of an inch short. Lots of unfilled space when looking from underneath the receiver up into the threaded holes. I was not comfortable with that. Asked the seller about that and they responded saying they only provided the one length screws but did issue a credit so I could purchase them locally. I tried the M4-.70x12 metric screws that another reviewer suggested but got mine from Home Depot (Everbuilt Brand) and the socket heads are too large in diameter and will not go into the mounting holes in Picatinny Rail. Plan to pick up the Hillman Brand ones at Lowes when possible. FYI, another reviwer stated that the M4-.7.0x12 screws were too short and used M4-.70x16 instead. Plan to try both 12 and 16 mm lengths later. EDIT: Updated 6-12-2020 I purchased the Lowes brand (Hillman) screws and same problem, the heads on these will not go down into the picatinny rail openings. Can't explain why my picatinny rail would be different from other reviewers. I ended up buying a set of gunsmith screws here on Amazon (Pachmayr Master Gunsmith Torx-Style Ring and Base Screw Kit) that had an assortment of 8x40 and 6x48 screws. The 8x40 1/2 inch (threaded part) fit but were slightly long so using the included thread verification tool (has threaded holes for 8x40, 6x48 and another that I can't recall) inserted a slightly long 8x40 1/2 inch screw into the 8x40 hole and ground off the excess, removed screw from tool (which cleaned up threads) on four screws and ended up with a perfect length screw on each of the four 8x40 holes in receiver.

It installed very easy and fits perfectly. It doesn't cover the safety or go past the chamber over the barrel on a Mossberg 590 12 ga shot gun. The 6 shells are held in tightly yet I didn't have any problem removing the 6 shells and reloading. The bad reviews are not accurate. I read all the negative reviews and was concerned after I purchased the item, but I figured I would give it a shot (Pun intended). I thought if it doesn't fit I will return it but it can't hurt to try it since there are so many good reviews. It goes on so easily I was pleasantly satisfied. It took me 5 minutes to install and I didn't need longer screws or any "LOCK TIGHT" to install it and snug it down securely. All the screws and the allen wrench came in the box that I used to install it. I will say though "WHEN ORDERING MAKE SURE YOU CLICK ON THE 12 GA OR 20 GA MODEL BEFORE COMPLETING THE PURCHASE". I think that is what throws people off to get a negative review because they receive the wrong caliber shell holder (12 ga 6 shell holder or a 20 ga 7 shell holder, that also threw me off in the description compared to the picture provided they have to describe the item on the Amazon page). And they do not realize it until they receive it and some people after receiving it. I ordered the product then had to cancel because it was set on the 20 ga, It was easy to cancel that order and reorder the 12 ga model. I don't have a picture but it fit perfectly on my Mossberg 590 12ga as pictured on other good reviews.. Sturdy metal and polymer material, built to last and take some good hard working abuse !!! I AM VERY HAPPY WITH THIS ITEM , IT IS JUST WHAT I WANTED !! I will order again if I get another Mossberg 500, 590 or 590A1 12 ga.

This product is fantastic! The material is incredibly strong, yet the gun still feels surprisingly light. Installing the slide was a breeze; it fit my 535 perfectly. To top it off, the appearance it gives my gun is incredibly sharp.

Got this for a Father’s Day gift. My husband said it was perfect.