The AR-15 rifle is the semiautomatic version of the military's M-16 rifle and is extremely popular with American shooters. AR-15 rifles are available in numerous configurations that are well suited for different kinds of shooting. Likewise, there are a variety of scopes that complement the AR 15. Choosing the right type of scope for your AR 15 rifle really depends on the type of shooting that you plan to do.
The most common scopes used by shooters with all different kinds of firearms, not only the AR-15, are variable-power scopes. Variable-power scopes have adjustable magnification ranges and are practical for medium- to long-range shooting. One of the most common varieties of medium-range scopes is the 3-9-power scope. These scopes have a magnification range of three to nine times your normal vision. Scopes used on the AR-15 often feature mil-dot reticles, which can also be used for estimating distance.
Fixed-power scopes are preset to one specific magnification setting. The most common scope used among AR-15 rifles is the 4-power scope; this scope provides four times your normal vision and is practical for short to medium ranges. Fixed 4-power scopes were among the first combat scopes designed for the M-16, but they are not your only options. More powerful fixed-power scopes are available for the AR-15.
Red Dot Scopes
Red Dot scopes are specifically designed for short- to medium-range targets. These battery-powered scopes do not have any magnification qualities, but they produce a red LED light that is visible only when looking through the scope. To the shooter the light will look exactly like the point of a laser beam. These scopes are particularly well suited for quick target acquisition at short ranges; however, once you start engaging targets at longer ranges, their accuracy diminishes.
A holographic sight has an appearance unlike a conventional scope and features a single window with holographic reticles projected onto it. Like the red dot scope, this sight does not magnify your target, but provides a quick point of aim. These sights are practical for short-range tactical settings, but lose their effectiveness with long-range targets. Holographic sights are battery powered.