Open Or Closed? Your Choice Of Emitters

Which style is better? Is an open-emitter optic design best? Or would a closed-emitter model work better for you?

 

What are we talking about?

An open emitter optic does not enclose the space between the emitter and the window the reticle’s image is projected onto. Likewise, with a closed emitter design, that area is sealed by the optic’s body and glass on both ends.

Who

Several companies make one style or the other, along with a few that make both. I may well—mistakenly—miss a company or two. I apologize in advance.

 

Open emitter manufacturers include Insights, Trijicon, Leupold, Doctor, Bushnell, Burris, Holosun, C&H Precision, Vortex, AmeriGlo, Riton, and more.

 

If you are looking for a closed emitter, look to Aimpoint – where the trend started with people bolting T1s onto slides several years ago. Other options include Steiner, Gideon, Lead & Steel, Riton, C&H Precision,

A few make both styles. Those include C&H Precision, Holosun, and Trijicon. Of those three companies, you have a variety of mounting options, including bolt-down into and bolt-over designs, as well as a proprietary bolt-over design that is only produced and sold by Holosun.

Footprints

Open

Since optics took off in terms of popularity, the community has had an issue with the variety of footprints available. Essentially, they boil down to these:

–       Trijicon’s RMR is probably the most common design. It is used by several companies, including both C&H Precision and Vortex;

–       Leupold Delta Point Pro is another option. Aside from the optic it is named after, it was the footprint designed into the military’s Modular Handgun System, which is being produced by Sig. While I thought this one would go by the wayside, Vortex is now producing optics that will mount this way. Sig is now producing optics that will work with this option;

–       A third pattern has evolved for optics mounted on smaller, single-stack concealed carry pistols. I have used smaller CCW-focused optics from Holosun and Vortex, both of which fit the same footprint. I do not have direct knowledge of what the Trijicon RMR-CC optic requires.

Enclosed

–       When Aimpoint’s Acro P1 hit the market in 2019, it required a base that was somewhat like a Weaver or Picatinny rail. Not identical to either, but similar in principle. Initially, only this company’s optic fit this base. That is no longer the case, as there are models from Steiner, C&H, Swamp Fox, Riton, Sight, Vector, Lead & Steel, and more. Due to some tolerance issues, TangoDown designed a new clamping bracket to ensure proper fit across a wider variety of bases.

–       Finally, Holosun’s first encloser emitter design – the 509T – has a proprietary footprint. While they have another optic that will mount on it, no other manufacturer is making one for it. 

Open Pros & Cons

            The open emitter line seems to offer a wider variety of optic sizes, extending from the Trijicon RMR-CC and Holosun K models to the 507Comp or the SRO. The larger windows for the wider designs reportedly make it easier for users to acquire the reticle. 

            They seem to print less because of the design and the lack of upper rear corners in the rear of the housing.

            Unfortunately, the open space allows for crud and debris to obstruct the shooter’s side of the lens or the emitter window.

 

Enclosed Pros & Cons

            These designs seem to withstand environmental issues – weather and crud/junk – better than open emitter designs.

            The battery is easier to access. We see side and top-mounted compartments.

            I prefer the clamp-cross mounting system that nearly all of these have in terms of the mount not failing. Regardless, if the optic is mounted correctly, then there is no difference between the designs.

            One drawback to the enclosed emitter design is that the box-like design contributes to some greater printing than the open emitter models.

 

How Do You Choose

You, as an individual, need to weigh each design’s strengths and weaknesses and compare them with your needs.

I have both concealed carry and competition pistols with open emitter optics on them. There is a definite size difference between them. Holosun’s 507Comp is a much larger optic than the other.

However, when I was still doing uniformed law enforcement, I chose to use Aimpoint’s Acro P2, an enclosed emitter design. I also prefer an enclosed emitter design for non-concealed carry—like when I teach and when the environmental conditions are adverse.

Those decisions are based on evaluations of my needs in different areas.

Final Thought

This article is a spin-off from a longer and wider discussion of the subject we had on The Guns Magazine podcast.