THE GUN ROOM

DEAD-EYE: Combat Optics

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Shooting with deadly precision has been made easier with the help of infrared lasers, magnification and night-vision scopes. But it wasn't always this easy.

"Wars aren't won by dying for your country. They're won by making the other poor, dumb bastard die for his country." - GEN George S. Patton Jr.

Trijicon TA11 with 3.5X magnification

Shooting is a cornerstone of infantry combat, and throughout the history of the infantry, rifle marksmanship training can be boiled down to hitting what you aim at. In that spirit, combat rifle development has been driven by the requirement to make battle rifles more lethal and more accurate. In a nutshell, there are three ways you can "improve" a battle rifle: Make the rifle itself more accurate, make the ammunition more accurate, or make aiming the rifle more accurate. Addressing the last point is where combat optics comes in. The art of precise rifle aiming has evolved from iron sights to the latest high-tech laser optics -- but how did we get here from there?

Sharp Shooting

Rifle sights, just like weapons themselves, have come a long way. The earliest firearms lacked any type of sighting equipment, while muzzle-loaded smoothbore muskets were, in effect, point and shoot weapons. Incredibly inaccurate and having a range of less than 75 yards, these early firearms were best employed by using massed volley fire at point blank range.

The earliest types of weapon sights were "iron" or open sights. These sights, either fabricated as an integral part of the weapon or added as an optional item, were introduced in the 17th century and remain in use today. Iron sights come in two forms, fixed and adjustable. Fixed sights are exactly what the name implies -- fixed and a "blade and post" variety where a notched blade is mounted at the back of the weapon and an upright post is mounted at the muzzle. Modern fixed sights come in a variety of formats and styles, including the use of radioactive tritium for shooting at night. Fixed sights are non-adjustable and essentially provide a means of rapidly aligning the barrel axis. This means that the shooter must manually compensate for actual bullet trajectory -- good if you're Clint Eastwood or a champion marksman, not good news for the rest of us.

M4 Carbine, M203 Grenade Launcher, M68 Reflexive Scope

M4 Carbine with a M68 Reflexive Scope

Truly adjustable iron sights, which could be adjusted to compensate for bullet trajectory, did not become available until the middle of the 18th century. While they serve the same purpose as fixed sights, either the front or rear sight is adjustable (or in some cases, both), aligning the sights with the actual strike of the bullet. When adjusted properly, these sights will ensure that the bullet will impact where the sights are aligned, saving the shooter from having to apply manual corrections.

Adjustable sights typically come in two varieties: those that can be aligned with the bullet's impact at a specific range (zeroing), and those that can be adjusted repeatedly for range. The M-16, for example, utilizes adjustable sights that establish a zero for a specific range. For targets at shorter or longer ranges, the shooter must manually correct for range (i.e., aiming low for targets inside the zero range, aiming high for targets beyond the zero range). The other variety, like those used on the German G3, have a rotating rear sight that is calibrated to specific ranges (100, 150, 200, 250 meters, for example) and the shooter need only to rotate the sight to the correct range in order to hit the target.

Each style has advantages and disadvantages. Fixed zero sights allow for faster engagement times, since there is no need to adjust the rear sight for range. On the other hand, the shooter must manually correct for bullet drop when the target is not at the range at which the target was zeroed. While this has the potential to make the weapon less accurate than one equipped with a sight adjustable for range, proper training can allow the shooter to make these corrections rapidly and accurately. Range adjustable sights, on the other hand, offer the advantage of being more accurate in the hands of a novice user in that they can be adjusted for range, which saves the shooter from having to manually compensate. One disadvantage, however, is the difficulty in adjusting the sights in a combat situation where targets vary at different ranges (e.g. 100 and 300 meters.) While it is possible to manually compensate for range based on the current sight setting, this is more difficult when factoring in the variable sight zeros associated with a variable range adjustable sight (e.g. manually adjusting for a target at 300m with a rifle sight set to 100m) than it would be for a rifle with a fixed zero.

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Super Scopes

Optical sights (scopes) use glass lenses to magnify the target image, making it larger at range and easier to hit. Optical sights first saw combat use during the Civil War, where sharpshooters armed with heavy rifled muskets and magnifying scopes were able to take aimed shots at very long ranges. Optical sights are very similar to adjustable iron sights, providing an accurate point of aim (zero) at a specific range. But their distinct advantage lies in target acquisition. Optical sights are described in terms of magnification -- so a 3X optical scope makes the target 3 times larger for a given range than non-magnified iron sights. Early sights were 3-5X, while modern scopes offer magnifications up to 10-15X. Just like adjustable iron sights, scopes can also be corrected for range.

Scopes are categorized by several criteria:

Objective Diameter: The diameter of the objective lens, which affects the amount of light that enters the scope as well as overall magnification
Reticle Type: Scopes utilize reticles as physical reference devices within the scope to represent the bullet's actual point of impact. Reticles are represented as intersecting lines (crosshairs) dots, chevrons, or circles, or a combination of the above.
Magnification: Scopes can either be at a fixed or variable magnification. Some scopes have a non-adjustable magnification (fixed at 3X), while others can be adjusted between specific limits (5-10X).

Various reticle styles

Modern scopes have become quite sophisticated. Many feature battery-powered illuminated reticles (for low-light operations or for use with Night Vision Devices), integrated rangefinders (such as a stadia or mildot rangefinder, which uses calibrated gates or dots to calculate the range to a target), or BDCs (bullet drop compensator, which provides bullet impact reference points for specific ranges). For sharpshooters and snipers, optical scopes offer the ability to make incredibly aimed long-range shots. Competition shooters routinely shoot beyond 1000 meters (.6 miles) -- greatly appreciated in a battlefield situation. In addition, by incorporating a rangefinder into the scope, the shooter no longer has to guess the range to the target, maintaining a high rate of accurate fire on a multi-target, multi-range battlefield.

Unfortunately, this kind of accuracy comes with a few drawbacks. As extremely precise instruments, optical sights do not hold up well under physical abuse. On top of that, they require precise alignment in order to be effective -- otherwise, they become as useful as a weapon with no scope at all. Finally, their high magnification allows for a very narrow field of view, limiting the amount of terrain that a shooter can view. To compensate, snipers often work in teams, with one shooting while the other provides local security by scanning for targets with a low-power spotting scope.

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Right on Target

One recent variation on scoped optics are the high eye-relief, low-power, close-combat optics designed to be used at relatively short ranges (25-250m). This provides the shooter with the ability to fire rapidly and accurately in short-range -- moving targets, moving shooter -- combat situations. These optics, referred to as either CCO (Close Combat Optics) or reflex sights, are typically low-power sights (the M68 CCO is 1X magnification, while the Trijicon TA11 is 3.5X) with simple illuminated aiming points, BDCs, and high eye-relief (eye-relief refers to the distance between the eye and the scope at which maximum FOV is achieved; sniper scopes typically have relief of less than 4" whereas the relief on CCOs can be as much as 12" or more). This not only allows the shooter to rapidly align the sight with the target, but also enables them to shoot with both eyes open, allowing the shooter to maintain peripheral vision while engaging targets. In addition, these scopes are typically parallax free, meaning that the dot or aiming point need not be centered within the scope's FOV. As long as the dot is on the target, the bullet will hit the target. These sights might enable the shooter to engage close range targets more rapidly and accurately, but "red-dot" scopes, such as the M68 CCO, provide no battlefield range adjustment at all. Just like conventional fixed iron sights, the shooter must manually correct for bullet drop when shooting at long-range targets.

The most recent aiming devices dispense with traditional aiming principles altogether, relying instead on a laser beam -- both visible and infrared -- to designate or illuminate the target. These devices, such as the AN/PEQ-2 designator/illuminator and the AN/PAC-4 designator, employ a laser beam to designate where the muzzle of the rifle is pointing. As a result, aiming through iron sights or other daylight-only optics is not required. The shooter need only orient the weapon so that the laser designator is on the target. In addition, the laser beam can be used as a target designator, so that leaders can designate either areas of coverage, or individual targets to be engaged.

AN/TVS-5 Night Vision Sight

While these designators offer some very distinct advantages, especially when engaging targets at night with NVG or with weapons that don't have night vision weapon sights (such as the AN/TVS-5), they do have some drawbacks. As with fixed sights, the illuminator is only accurate at the range where the sight is boresighted or zeroed. Engaging targets above or below that range requires manual correction on the part of the shooter. In addition, the laser beam is visible to the naked eye (and visible to NVG in infra-red mode), which can reveal the shooter's position to enemy soldiers equipped with similar devices.

What's Next

What does the future hold for combat optics? Information integration and ballistic solutions will be computed automatically. A built-in BDC will manually super-elevate the aim point to compensate for bullet drop. Future systems will take into account all important factors (range, barometric pressure, temperature) and automatically adjust the reticle for precision shooting. As of now, such things can only really be compensated for through experience. With current scopes, range must first be determined and the reticle physically adjusted by using windage knobs to crank the sight up or down.

One such system working in this direction is the Barrett Optical Ranging Sight (BORS.) The BORS automatically compensates for air pressure and temperature and rather than having the shooter count clicks on the windage knob. When making reticle adjustments for range the BORS uses a range display, requiring that the shooter simply (and rapidly) input the correct range. The sight then automatically moves the reticle. While the initial BORS system does not have an integrated range finder, the following version is expected to incorporate one, which will enable to BORS to automatically enter the range and adjust the reticle accordingly.