Mounting Optics on a Vent Rib Shotgun Barrel

I really like Mossberg pump shotguns. Mossberg evidently has some folks with innovative minds in their pump gun division, and the guns reflect that in almost unmatched versatility. My old Model 500 12 gauge, for instance, came with a plain Jane barrel that helped me account for many, many rabbits, squirrels, and other small game, while my brother borrowed it and shot a nice deer once upon a time. Later I switched to a slug barrel for awhile, and it now wears a .50 in-line muzzle loader barrel. Always a fan of improved optics, I liked the fact that the slug barrel had an integral pictatinny scope mount, but to scope the muzzle loader – which came with good, rifle-type open sights – I had to turn to an after market mount that incorporates a side plate that uses existing screws and holes – no gun smithing, drilling, or tapping required. When I recently picked up a Maverick 88 pump by Mossberg in 20 gauge as a night-time varmint and home defense gun, I wanted to use a C-More Railway red dot sight on it, for faster target acquisition than the front bead on the stock barrel can provide.

When looking at mounting options, I picked up an older, more modestly priced red dot I once used (and shot loose) on the slug barrel of my 500. It was sitting on a mount made to fit a Weaver-style base to the dove tail grooves on a .22 rim fire – and amazingly it slid on the vent rib of the Maverick barrel as though it had been designed to work there. The little base has a top set screw and three tightening screws on the side to hold it in place, and did not seem to mind the 20 gauge recoil. It worked so well I was tempted to just leave it in place and use it, but decided to try a slightly different approach as long as I was testing this type of mounting system.

This mount is actually for mounting a full size scope or red dot on a .22 rim fire by using the adapter that fits in the rim fire's Dovetail grooves.

This mount is actually for mounting a full size scope or red dot on a .22 rim fire by using the adapter that fits in the rim fire’s Dovetail grooves.

Sun Optics sells a “shotgun saddle mount” that really isn’t a saddle mount. It slides on the vent rib of a shotgun so equipped,and is held in place by small “plates” that go under the rib and are tightened to the mount with two screws. As I recall there were three of these plates included, but might have been two. Because of the spacing of the pillars that hold the rib to the barrel on my 88, I am currently only using one plate, and it seems to be holding well. The Mossberg in this configuration have a two sight bead arrangement – a “silver” bead at the muzzle, and a gold bead about halfway back and on top of the rib. The gold bead keeps the add-on mount from sliding into a position that would allow using more of the mounting plates. Since the gold bead serves no useful purpose, I intend to take it off and beef up the mount, eventually.

This much mount has a much longer picatinny rail and clamps to the top of the vent rib on shotguns so equipped.

This much mount has a much longer picatinny rail and clamps to the top of the vent rib on shotguns so equipped.

Either the Sun Optic mount or the much lower priced Sniper mount will do the job for you, the longer Sun Optics unit just offers more flexibility in where the optic can be mounted. In my opinion, and for what I intend to use this shotgun for, my red dot sight mounted with either one makes hitting what I need to hit a surer proposition!

About MikeH

Texas hunter and fisherman for 50 years, published outdoor writer since 1979, licensed charter boat operator from 1982 to 2013. Past Member, Board of Directors, National Association of Charterboat Operators, current member Environmental Advisory Committee to the DOE and the Strategic Petroleum Reserve. Married to Dorothy since 2000, one son, Michael who is recently married and living in Nederland, Texas. My wife and I live in Oyster Creek, Texas, near Freeport, and have a hunting property outside of Brazoria, Texas.
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