ohhunt® Shotgun Ventilated Rib Mount Adapter Picatinny Rail - 5 Slot 2.16 inch

Will only fit. 310 vent rib.
The screws are to long they touch the barrel. I had to cut them shorter. After hunting season is over I'll find the proper length screws. For another 10 bucks you could include different length screws and lock tite. You would have better reviews and more stars. It does work as it should.

The quality of the set screws was so bad they just stripped easily. Also the 4 set screws that hold the two plates in place were too long and hit the barrel so they could not be tightened.

ohhunt® Ventilated Shotgun Rib Mount Picatinny Rail - 3.35 inch 8 Slot

The 4 screws that hold the base on the rail afe too long for my Remington 870. They have to be cut off in order to put the sight on. I haven"t had a chance to try it out yet.

Works great on rib of my beretta shotgun. Make sure to use loc tite on screws. Do not over tighten especially side screws. Stop tightening when resistance is felt. Have a red dot on shotgun for wing hunting. Have shot over 200 rounds so far..no problems!! Also, mounting screws do not touch barrel on my shotgun.

Installed in 20 min after relocating a few times
Solid and looks good

Perfect

Works as it is intended to. But it’s not for all shotguns. The slot that accepts the actual rib of the shotgun is not wide enough for some shotguns that have exceptionally wide ribs. Check before purchasing.

People that complained about the mount and screws might be over torquing
them. Putting this mount on your shotgun isn't like working on your car.
The screws can be put in snug enough to do their job, without striping them out.

I would buy it again. Universal may be a loose term. Every gun may vary... the hardware stripped out easily