If you are anything like me, I’m sure that you have found yourself in your friend’s basement discussing the finer points of co-witnessing back up iron sights on platforms other than the AR-15. One of these platforms that came up was the Benelli M4, and many laughs ensued as we put all of the optics that we could find onto the factory rail.

Red dot sights (RDS) and mini-red dot sights (MRDS) are becoming more and more popular on both pistols and shotguns. The market for RDS and MRDS on pistols has already been adequately addressed, but the shotgun issue hasn’t received as much attention. There are several companies that are offering stocks with adjustable length of pull and comb to place your eyes on the proper plane, but there hasn’t really been any attempt to manufacture or offer a mounting solution that allows for co-witnessing of iron sights with any RDS or MRDS; unless you happen to be one of the few people who own a FN TPS.  It didn’t seem like any company really cared to address the issue, until now.

Enter the Scalarworks BOR100. This $119 RMR mount is a really interesting piece that provides direct mount capability on a rail that is roughly the same size as the factory Benelli rail. This means that you do not need an additional mount to attach to your Trijicon RMR to your shotgun. This does three things for the end-user. First, it means that your mounting set-up is lighter, as the RMR no longer needs a picatinny mount; on top of that Scalarworks specifically designed their mount to be even lighter than the factory Benelli mount; I don’t know how they did it, it’s magic. Or maybe it’s just because they took the time to machine out the excess material from the underside of the rail.  Secondly, it makes your setup more reliable, in theory, by removing another point of failure, the picatinny mount.  Third, and most importantly, the RMR mounts directly to the Scalarworks mount with the included hardware. This gets the RMR lower on the shotgun, which actually provides for co-witness with the factory Benelli iron sights.

I think it’s worth mentioning that co-witnessing your RDS with iron sights is really a matter of personal preference, more than it’s objectively better than not. I am in the camp that likes the ability to co-witness. With the Benelli M4 I think it’s particularly advantageous to have the optic on the same sight plane as the irons, which is more a matter of ergonomics; that will be discussed later.

If you’re running a M4 with the fixed stock the BOR100 is pretty much impeccable from a functional standpoint. However, if you run a collapsible stock you’ll run into an issue. The problem is really with the Benelli M4, and not the BOR100, however sighting does suffer as a consequence. With the M4, the buffer tube that the adjustable stock rides on is angled down from the receiver. As a result, the height of the cheek weld changes, relative to the sights, between each adjustment. So with the BOR100/RMR setup, you really can’t use the site when the stock is fully collapsed, not that you can use the iron sights either.

I’ve used several other optics on my M4, an Aimpoint CS, ML3, and T1 Micro. Most of the time I was forced to use the intermediate stock position because the optic would sit so high relative to the cheek weld.  Only with a T1 in the factory low mount was it ever close to comfortable, but there was no co-witnessing happening.  I always felt as if I was sacrificing control of the weapon for a good sight picture.  If you’ve ever shot a Benelli M4, it becomes apparent very quickly that it was designed to be shot with the iron sights, not with an optic sitting up on a mount. After all, it is part of the Super 90 lineage, and its predecessors certainly weren’t designed with the use of optics in mind. Honestly the factory rail on the M4 seems like it was an afterthought they just added, because you know, rails are kewl!

The shortcomings of the M4 shouldn’t overshadow the BOR100, Scalarworks did an amazing job given the constraints of the platform. The BOR100/RMR is hands down the best red dot setup I’ve ever run on the M4.  When you shoulder the weapon and settle into a comfortable cheek weld the red dot is right there.  There is no fidgeting to get a good sight picture or compromising your control of the weapon. This is because the optic is right there on the same plane as the iron sights; and with how the weapon is designed, that’s where you want it.  Without actually running two M4s side to side I can’t quantify that the BOR100/RMR is faster, but I’d be willing to bet money on it.  Follow-up shots seem to happen quicker than I’ve ever experienced before.

Other than just being really functional, the BOR100 is a very well made piece too.  The fit and finish on the mount is among the nicest that I have seen. It is elegantly designed and really works with the lines of the shotgun. I think it’s safe to say it looks better than the factory rail.  The machining is very clean with no noticeable flaws in the anodizing.  The people over at Scalarworks obviously have a handle on design.  Unlike some accessory manufacturers that go over the top with branding, they limit it to a tasteful but still apparent logo laser engraved in the front.

Even though this mount is outstanding, there are still a few things that I might want to see changed or offered for a future variant. One thing that I think would be awesome is if there were options for different optics. I know that everyone loves RMRs, but there are lot of people that I imagine would love to see an integrated mounting option for a T1, or a less expensive micro red dot like the Burris FastFire. That would all be dependent on if there are physical limitations to what can and can’t be mounted sufficiently low enough. Another things that I would love to see is doing away with the rails entirely, making it as just the optic mount. This would keep it super tidy and streamlined; and make the whole package look cleaner, in my opinion.

The way it is now, there is a reasonable amount of picatinny real estate in front of the optic. To be completely honest, I am not really sure what this section of rail is for. You could put a light or a sling swivel there.  A light really needs a pressure switch, or it is too difficult to manipulate.  A Surefire Scout on a Thorntail is really the only way to get a light far enough forward, and even then it’s not ideal, and the light is sticking out way off the firearm. The idea of putting a side mounted QD swivel on the top rail is neat, however, would you really want to put that kind of stress on your optic mount?  When it comes to mounting a sling or a light, I think there are better options for setting up a M4, in the end it’s up to you how you want to use the rails, now that you don’t need to mount an optic to them… Other than these few somewhat shallow criticisms, I do wish that the mount came with screws for mounting to the receiver.  The factory hardware isn’t great, but sourcing the obscure #8-40 weaver standard screws would only drive the price up further.

This mount is very solid and overall very impressive. It was great that I got to play with this thing for free, but now I have to buy one. Scalarworks is definitely a company that takes a lot of pride in what they are producing and offering, and now every Benelli M4 that I see is going to be naked without one of their BOR100 mounts.  Considering a decent RMR mount is roughly $60-$70, and you’re replacing a less than impressive factory part on the Benelli M4, the Scalarworks BOR100 isn’t a bad deal at $119.