MonstrumSide Saddle Shell Holder for Mossberg 500/590/Shockwave Series Shotguns

For a home defense shotgun this is a must-have accessory. It enables you to carry extra ammo while also providing a mounting platform for powered optics, such as a red dot. Most shotguns have limited ammo capacity, and you're not going to have time to grab extra shells if you hear a bump in the night. Having those extra shells already mounted to the gun gives you the opportunity to reload, which could be a lifesaver in a hostile encounter.This product surprised me with its quality and price point. It works great, fits great, holds up well under heavy use, and looks awesome to boot. Buy one - you won't be disappointed.It will fit the Mossberg 590 shockwave. Be sure to order the correct version - there are options for 12ga and 20ga. In order to install this product your shotgun must have a drilled & tapped receiver - in other words, little flat-head screws running down the top centerline of the gun.You may consider installing a larger front sight, because this product adds a little extra height to the receiver, and may make it difficult to aim with a standard bead... or just get a red dot and install it on the rail. Also consider using loctite when you install to prevent the screws from loosening under strain from recoil.

Installed on a Mossberg 500. Super easy to mount.

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.

Awesome looks great

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 6-12-2020I 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 was very easy to install and so far it seems high quality. It fit perfectly on my Mossberg 590. The 12 gauge shell holder fits the shells snugly and comfortable to use. Now I have to actually give it some range time and see if it maintains the intergrity. If this comment is not updated with any negative experiences from future use, buy it!

Installed on my 590S model but it has a plate from the factory and the screws in this kit are not long enough for the rear holes due to the plate. You will need #8-40 x 1/2” gun screws to install on a 590S

Perfect for what I wanted just perfect good price