Ultimate AR-15 Buyer’s Guide

The AR-15 is the single most popular firearm in the United States. Millions of them have been sold over the past 50 years, both the original Colt versions and those produced by other manufacturers. There’s little wonder why this should be so: Not only is the design accurate, reliable and robust, but also because of its history in various forms as a military, law enforcement and tactical rifle. It has become widely popular for home defense, hunting and as an accurate and as a fun range rifle.

If you are considering buying an AR-15-type rifle for the first time, you have a very wide variety of options available. You can choose from many different styles, calibers, furniture and add-ons. It may seem daunting to make these choices, so we at Omaha Outdoors want to explain some of the basics of the AR-15, so you can decide what suits your exact needs.


Designed by Eugene Stoner in 1959 for ArmaLite Corporation (the “AR” designation comes from the company name), the AR-15 is an air-cooled semi-automatic rifle that uses a gas-fed system to cycle a new round into the chamber after each shot. ArmaLite sold the rights to the design to Colt in the early 1960s so, technically, only Colt-made rifles of this type are officially called “AR-15’s” but the term is used casually for the rifle across all manufacturers’ models.

The original AR-15 was chambered for the 5.56 NATO cartridge, but models are now available in a wide variety of calibers, including .223 Remington, 300 Blackout, .308 Winchester/7.62 NATO and even some handgun calibers.

Rifle versus Carbine

There is often some confusion over the terms “rifle” and “carbine,” since some models are called by one or the other name. The overall length of an AR-15 model is used to determine which category it falls into. Generally speaking, a rifle will be about 40 inches (give or take) long, while a carbine will measure about 36 inches. This length is measured from the butt of a fully-extended stock to the muzzle, so, in general, the difference will be determined to a great degree by the length of the barrel. (Note that the term “mid-length,” which you will sometimes see in model descriptions, refers to the position of the gas port on a barrel, not the length of the barrel or the overall length of the firearm.)


The profiles for barrels include weight (thickness), length, rifling, fluting and lining. Most shooters are willing to accept the choices of the rifling – the twist ratio – made by the manufacturers, whose experience has led them to designs that provide the optimum rifling for a particular caliber. Your choice of weight and thickness, however, will depend upon how you intend to use your rifle: Are you looking for a range rifle for rapid-fire or long distance accuracy, or do you want a more general-use rifle?

A heavier barrel – HBAR or “bull” profile – will not heat up as quickly as a standard barrel, allowing for less deformation (and therefore greater accuracy) even during extended rapid fire. The trade-off, of course, is weight; a heavy-barrel rifle is going to be more challenging to carry in a field environment. While fluted barrels allow for faster cooling, but they tend to be more expensive.

By the same token, longer barrels – 22 or 24 inches – can improve accuracy, but they are going to be more awkward to carry in the brush. If hunting and/or home defense your primary purpose for an AR-15, you may want to choose a 16- or 18-inch barrel model.

Gas Systems

All AR-15s use gas-driven operations to re-cycle the action and chamber a new round after each round is fired. A gas port (a small hole) in the barrel re-directs a small amount of the expelled gas from a fired cartridge into a gas port. In direct impingement systems, the original design for the AR-15, the gas travels through a gas block into a small tube which leads to the receiver, where it powers the bolt carrier group to cycle the next cartridge into the chamber. Many models have an adjustable block that can reduce or increase the amount of gas re-directed. This adjustment can be useful when a shooter uses different types of ammunition, such as target rounds and hunting ammunition, so they can adjust for different cycling rates.

In recent years, the gas piston system has been adopted for some AR-15 models. Gas leaving the gas block drives a piston, which compresses a piston spring and pushes an operating rod to move the bolt carrier group. The advantage is that, since the gas does not directly encounter the bolt carrier group, the chamber remains cleaner and cooler and is therefore less likely to foul even after firing multiple magazines of ammunition. The drawbacks are that gas piston rifles tend to be more expensive and some shooters report slightly less accuracy.


Perhaps the most personalized part of an AR-15 is its stock. There are so many designs and varieties available that any shooter’s individual needs can be met. The standard solid stock is, of course, the most familiar, but some shooters prefer the skeleton design for weight savings. Others choose the collapsible design, particularly the six-position models, which not only allow for different arm lengths but can be used for different shooting styles. There are also many different adjustable stock designs, which allow the position of the butt plate and the cheek rest to be dialed in for the most comfortable shooting platform; the most intricate models are often called “sniper stocks” since they can be used for accurate long-distance shooting.


The forearm of an AR-15, called the handguard, comes in several varieties. The solid handguard is a standard “drop-in” and can be easily attached to the rifle. For shooters who like the classic M-16-like look of an AR-15 and prefer to use iron sights, this is an inexpensive option. Drop-in handguards with Picatinny military-spec (MIL-STD 1913) rails are also available, which allow the shooter to easily attach such add-ons as sling swivels, bipods, foregrips, lasers and lights – although they are not suitable for optics, since they are not stable enough to keep a scope zeroed in. A very popular option is the free-floating handrail, which does not attach to the barrel; it is mounted to the upper receiver. This not only allows a stable platform for optics, but, when used with a low-profile gas block, can extend for the entire length of the barrel. This allows much more room to really go tactical with add-ons, particularly when the handguard has quad rails. Keep in mind, though, that adding devices to the handguard will change the center of gravity for the firearm.

Add-Ons, Optics and CeraKote

Two words: Go wild. An AR-15 can be like a blank canvas: Add any scope you like, attach a laser and/or a light source (visible or infrared) and you’ll only be half-way there. When you order an AR-15 from Omaha Outdoors, you can have it treated with CeraKote in any color (or combination of colors) you desire: From zombie green to bright pink, you can customize your new rifle to stand out from all the rest! See our section on cerakote services for more information.

The AR-15 has become America’s Gun for the 21st century. We are confident that you will find the model in our inventory that best suits your needs and shooting style. If you have any questions, please don’t hesitate to call or use our handy message system; our friendly and knowledgeable staff will happy to help you find the AR-15 that is right for you.