Trijicon’s ACOG sight is an excellent example of a sight that needs no power to still be useful—so much so it has been standard issue for the U.S. Marine Corps for many years.
Ever since my first encounter with an Army-issued Aimpoint 5000 in the early 1990s, I’ve appreciated the ability of electro-optical sights to get me on target quickly and effectively. At the same time, having to rely on batteries has always been a sort of mental Achilles’ Heel for me. I was so battery conscious in those pre-auto-shutoff days that I talked one of my unit’s communication wizards into fabricating a pressure switch for my red dot. The result was an instantly accessible aiming point, without my having to “burn” the battery continuously while patrolling. It sounds rudimentary now, but in those days, it was a novel capability. It also earned me more than a few eye rolls from teammates.
Another challenge was presented by our early sights’ rail mounts. Positioned atop a non-removable carrying handle, the Weaver adapter that served as an interface between optic and rifle made iron-sight use difficult. These mounts left tiny windows through which to see our front sights, slowing down target acquisition and eliminating any appreciable field-of-view. With dot-sight battery lives that were measured in tens of hours at that point in time, actually needing those backup sights was a fairly regular event.
The advent of flattop modern sporting rifle (MSR) upper receivers, co-witnessed sights and [later] offset backup sights (BUS) remedied those iron-sight limitations. However, there are times when eliminating every bit of excess weight and bulk can compel one to eliminate even backup sights. While not recommended on any rifle that may be used in defense of life, I admit that I have been in operational situations that required me to get rid of my BUS, gambling that my primary optic would not fail. Fortunately, I had optics with redundant aiming systems built-in so that they were functional even if my batteries died at the wrong time. Today, we have many more optical choices that meet this same powerless need than were available a decade or so ago, along with the advantages of battery lives measured in tens of thousands of hours.
The most obvious choice for an optic with redundant aiming points is an illuminated, variable-power optic. In cases where close-range or rapid acquisition is required, low-variable-power optics (LVPOs) rule the roost. We have covered them previously and in relative depth, so I will not delve into LVPO options now. However, I will repeat my earlier-stated belief that, where weight and bulk are not primary concerns, an LVPO riflescope with an etched, illuminated reticle is still the most flexible sight available.
When issues such as length and weight make LVPOs untenable, another good option is a fixed, low-power optic with an etched reticle and some form of illumination. Trijicon’s battle-proven ACOGs are the top choice here for good reasons. These riflescopes are extremely durable, have clear glass and are available with both tritium and fiber-optic illumination, backed up by etched reticles. This trifecta of aiming mechanisms allows the shooter to engage targets in any lighting condition and without any battery concerns or need for switches. A downside to the ACOG’s design is that some people find it difficult to rapidly acquire targets with magnifications of 2X or greater. ACOGs are also fairly heavy for their package size, due in part to their structural integrity. One solution to both problems is the 1.5X ACOG. Learning to quickly hit close targets with these tiny models is not difficult, and the diminutive size of the 16 mm objective model is a home run with weight-shavers. Unfortunately, ACOGs are not cheap and all have relatively short eye relief that precludes their use on certain platforms.
Fortunately, Trijicon is not the only company using an etched-reticle design in a fixed-power, illuminated optic. Vortex has introduced models with similar capabilities, such as the currently offered Spitfire AR. This 1X prismatic sight has an etched BDC reticle with red and green illumination options. Primary Arms is also in the game with its SLx 1X Micro Prism and GLx 2X Prism sights. Like Vortex, Primary Arms’ sights back up its battery-powered reticles with etched glass. Therefore, whether viewing a target in bright desert sun or with the aid of a gun light in low-light conditions, a usable reticle should be there if the glass is intact. Each optic also provides more generous eye relief than either ACOGs or most LVPOs.
A further hybridization of the backup power trend comes in the form of small, dot-type sights that complement their batteries with fiber-optic panels. Lacking etched-glass reticles, these optics do not provide the same level of powerless backup as those described above, but they are nonetheless superior in illumination capabilities to sights that are solely powered by batteries. Most makers use the term “solar” to describe such optics, but even within a single manufacturer’s product lines, this term can have multiple meanings. In some cases, their sun-fueled panels simply remove a portion of the power demand from batteries, but they do not power reticles by themselves. In other models, such as SIG Sauer’s Romeo 4T and Holosun’s 510C, you can remove the batteries altogether and still make use of illuminated reticles, so long as a moderate amount of ambient lighting is available. Each sight manages this capability differently and reticle options are limited without functioning batteries, but at least these optics are operable in moderate lighting if their regular power sources suddenly die.
While I have not covered every optic in the above categories, those described are representative of the ever-increasing options for powerless sights. For people who appreciate redundancy, this is a happy trend. One day, some smart person is going to figure out how to harness the human body’s electrical field or draw from static electricity in the atmosphere to power our rifles’ electrical devices. I may be long gone by then, but it is nice to imagine that future generations will no longer need to fill their pistol grips with two or three different types of spare batteries.