RECONSIDERING THE DUAL ILLUMINATED RMR
I have been working with these since January and carrying one daily on my Glock 17 to get a first hand idea of the advantages and liabilities of the units. Specifically I am referring to the Trijicon Dual Illuminated RMRs: The RM03, 04, 05, and 08. These have 13 MOA, 7 MOA, 9 MOA and 12.9 Triangle respectively. I am referring as well to the Amber Dot units and not to the Green Dot units. The green do units require a pinkish hue to the glass and we will discuss those later.
The Dual Illuminated units have a plastic strip along the top of the RMR that acts as a fiber optic collecting available light to power the dot. It is also powered by a tritium element that ostensibly will last ten years or more. These do not require any batteries and that is both where the advantage and liability lies.
It is an advantage because all one need do is install it on their slide and run it unconcerned about batteries for years. In fact, the tritium will last for 12 years or more. This is favored by men who travel in the outskirts of civilization where there may well be no batteries at all to be had. The concern often voiced is that the fiber optic and tritium are dependent on the existing light conditions to function at their utmost.
Think of this in terms of tritium sights. Unless you go into a sufficiently darkened environment, you will not see them glow. This is the same situation with the tritium in the RMR. It must be dark enough for that tritium-powered dot to stand out. The plan is that if it is not dark enough to make the tritium stand out, you will have the fiber optic to power the dot. Most of the time the concept works perfectly. The concern is that when the available ambient light is insufficient to power the fiber optic, but the darkness is insufficient to allow the tritium to stand out, you will have a dot fade out.
1). Early pre-sunrise morning, or just at sunset. This is an area where identifying targets is also difficult and you would be unlikely to engage anyone at distance simply because you would not likely see them in the first place. Use of the handgun would be the same as if you were equipped with iron sights only.
2). Engaging a threat in an illuminated environment while you are concealed in a dark environment. The situation is best illustrated with you inside the house wanting to engage a bad guy approaching from the outside. Use of the handgun would be the same as if you were equipped with iron sights only.
3). When using a weapon mounted light. As soon as the light comes on, there is insufficient darkness to power the fiber optic (as it is directed toward the threat and not in an ambient situation), and yet insufficient darkness at that point to see the tritium. This is what some term as "washout". Again, use of the handgun would be the same as if you were equipped with iron sights only.
At all other times excluding these, the Amber Dot RMRs serve as well as their red LED counterparts.
So the first question is whether these special situations are so notable that we absolutely are better served by going with the battery powered units instead. Secondly - if we opted for the dual illuminated unit becomes how to minimize your liability when using the system in the three situations shown.
To answer the first question, I don't think the situations listed are a definitive reason to discount the dual illuminated units. The reason is that we have answered the second question with an interesting workaround. It is a tactical solution rather than a technical one.
First is the use of standard tritium sights in conjunction with this category of RMR. I like my design of course as I think it is simpler than the others on the market (a front dot and a rear dot rather than three dots), but the same effect can be obtained using any of them.
The shooter trains his eye to visually shift focus from where he expects the dot to be - to the iron sights any time he has difficulty getting on the dot. This is the "visual immediate action drill" used for a failed battery and it is just as valid for a washed out amber dot in these unusual events. In minimal light but insufficient darkness we found that the tritium sights not only help keep the pistol aligned and usable under those varying light conditions, but also guides the eye back to the dot even if it is fainter than usual due to circumstance.
Moreover, the shooter must remember that he has "dual sighting systems" on his pistol. If one is unusable he transitions immediately to the other one. With this in mind, the shooter can optimize the advantages and minimize the drawbacks of the Dual Illuminated RMR. And with the added reliability and simplicity of the dual illuminated units, there are few reasons to not select it.