AR-15 Buyer’s Guide

The AR-15/AR-10 or Modern Sporting Rifle (MSR) is currently the most popular firearm on the market with hundreds of manufacturers offering different models, variants, and accessories. Choosing the right rifle to buy can often be daunting, but luckily we’re here to help!

AR-15 rifles are modular platforms, so there are many options to consider and knowledge you will need to make an informed decision. When you are looking to buy an AR-15 rifle, it is important that it meets all your needs and expectations.

Here’s everything you’ll need to know about the AR-15, as well as some of the adaptable features you can add to make your AR-15 best serve you and your firearm needs.

Brief History of the AR-15

Early development of the now famed AR-15 occurred in the 1950s under the guidance of Eugene Stoner, a former Marine and Army Ordinance technician, who worked at Armalite.  Stoner was asked to develop a potential replacement for the US Army M-1 Garand. He created the AR-10 in 1959, with the “AR” standing for “Armalite,” not “assault rifle.”

Army officials asked to adapt the AR-10 into a smaller model, which led to the AR-15. Both the AR-10 and AR-15 took advantage of a new steel barrel extension that locks up the bolt instead of the receiver, which allowed for a change to lightweight materials, like aircraft grade aluminum, in construction. In 1964, the military began using the M16, the full-auto version of the AR-15, as their standard service rifle.

Today, AR-15s fall into the class of modern sporting rifles (MSR), and it is the most popular general-purpose rifle platform for sale on the market.

Calibers and Capabilities

What is interesting about AR rifles is that they are not really just a single rifle type; rather, they have a set of common design specifications that lends itself to a diversity of capabilities.  AR-15 style rifles feature either direct impingement or piston-driven operating systems, 16-20” chrome-lined barrels, various handguard lengths and an assortment of adjustable buttstocks.

The AR-15 style rifle is designed for tactical applications perfect for law enforcement or self-defense.  Many models feature a tactical modular handguard great for accessories like lasers, bipods, and flashlights.

The AR-15 is a smaller bore caliber rifle chambered in .223 Remington / 5.56x45mm, but a host of  ammunition is compatible with this versatile design configuration, like the more powerful 300 blackout, 6.5 Grendel, and 6.8 SPC ammunition calibers.

The original .223 Remington / 5.56x45mm is a very small and light bullet that possesses muzzle velocities between 2,800 and 4,100 ft./sec.  The .300 AAC Blackout is also a great AR caliber platform as it allows for a wide range of bullet weight and velocity combinations, and it is compatible with the .223 / 5.56 mm rifle cartridge.  The 300 Blackout is also compatible with the magazine used for the .223/5.56.

While the AR-type rifle is meant for use in applications less than 400 yards, it has been adapted into a longer-range player. An example of this is the 6.5 Grendal. The origin of the 6.5 may be traced back to the Soviets’ 7.62×39, which was modified for European competition then retooled by a series of U.S. competition shooters looking for exceptional performance.

The 6.5 Grendel is designed to fit the traditional AR-15 caliber size; in fact, a standard magazine clip can fit about 26 Grendels. The low-drag, long and thin bullet can reach out to 800+ yards.

AR style rifles currently come for sale in two main calibers:

  • AR-10 Models:62 NATO/308 Winchester
  • AR-15 Models:56 NATO/.223 Winchester

Compared to the AR-15, the AR-10 accommodates a larger bore caliber in the AR platform. The most common is the .308 / 7.62x51mm NATO bullets that were designed for accuracy at great distances. With the right set of optics, optimal performance can be achieved out to 1,000 yards.

An additional caliber worth noting due to their recent popularity is the 6.5 Creedmoor. This long-range cartridge often used in DMR (designated marksman rifle) platforms has become one of the most popular rifle calibers in recent years due to its versatility and outstanding long-range performance. The 6.5 Creedmoor is also compatible with a standard 308/7.62 magazine.

AR-15 Operating System

The AR is a self-loading rifle that exacts a basic set of functions mechanically without user assistance. These rifles operate via a gas system, consisting of a gas port that drills into the barrel to send the bolt through the gas block, tube and gas key to release the projectile or bullet. By bleeding propellant gases through a port at the end of the barrel and channeling the gases back through a tube to directly strike the bolt carrier, the projectile is fired. As the projectile is propelled forward by a spring, a fresh round is pushed into the barrel’s chamber.

There are two standard varieties of gas systems available for ARs: carbine and rifle. The carbine system is 7 inches from the action with a port size about .062” in diameter. The rifle or full-length gas system is 12 inches from the action with a typical rifle port about .096” in diameter (each manufacturer has their own specs).

Both systems function to operate a gas piston or a direct impingement system. The farther the propellant gas travels through the barrel before it bleeds into the gas port, the longer the dwell time or amount of time the bullet will remain in the barrel after the gas port is pressurized. This results in less residual pressure or recoil. Also, the farther the gas propellant travels down the barrel, the larger the port, as it needs to create the desired pressure.

The two types of AR-15 operating systems include:

  • Gas piston systems use the pressure of the propellant gases that build up when a round is fired. The gas pressure gets channeled into a separate cylinder, which contains a small piston that cycles the action by pushing the bolt carrier rearward to handle the ejection process. The bolt is then pushed forward by a spring, which strips the round from the cartridge and loads it into the chamber. The gas piston system runs cool and clean but can have more felt recoil so it can be slightly less accurate especially with follow-up shots. Gas piston AR-15s will run cleaner, are easier to maintain and are often more reliable than some direct impingement operating modelsDirect impingement systems are the most common and the original operating system designed by Eugene Stoner. This system has been used in the AR-15 since its birth. Gas systems activate by channeling the expanding, intense gas pressure that builds up behind the bullet when a round is fired. The supercharged gas pressure gets diverted through a small directed gas port/tube in the barrel, which gets channeled by the gas block, down the gas tube, and back into the gas key located on the bolt carrier. This pressure pushes the bolt carrier group rearward while also ejecting the spent cartridge round. As the buffer tube thrusts the bolt carrier group back into the battery, it simultaneously strips a fresh round from the magazine, loading it directly into the chamber of the barrel.

 

Direct impingement systems typically run dirtier than piston operated ARs, so they require thorough cleaning and maintenance and are not always as reliable. Throughout the years, there have been many improvements to this operating system and is still the most popular between the two. Roughly 75% of AR-15s feature a direct impingement operating system.

Barrel Lengths

The most common barrel lengths include 16”, 18”, and 20”. Having a longer barrel will provide more room for the powder to burn and give you higher velocity. A quicker moving bullet gives the atmosphere less time to disturb the course of the bullet. Shorter barrels can be just as accurate because they are firmer and less prone to barrel movement during shooting.

In addition, shorter barrels are lighter and can be easier to handle. However, they have higher uncorking pressure, meaning there will be amplified sound compression levels and flash concentration, which leads to additional cycling and greater recoil, but with less accuracy.

Shorter barrels will also be less accurate at greater distances because of their lower velocity.  There is no better or worse barrel length, as this factor is completely dependent upon the application and usage of the rifle. The most common AR-15 barrel length is 16.5 inches.

Barrel Profiles

 

Lightweight

Lightweight barrels are perfect for those who plan on being out for long periods of time, such as during a day of hunting. In addition, they can also be more maneuverable. Lightweight barrels will often be steel core wrapped in aluminum. The core is welded to the jacket, aiding in heat dispersion and drastically decreasing weight.

Another type of lightweight barrel is the carbon fiber barrel. Manufacturers like Christensen Arms, Nemo Arms, Barrett and Proof Research have developed some of the lightest and best-performing carbon fiber barrels in the industry. The process of producing a carbon fiber barrel can be complicated.

Most manufacturers will start with a stripped down stainless steel barrel, then finish it with a carbon fiber jacket. Proof research will wrap the stainless with an aerospace-grade carbon fiber that is strengthened with a specific resin of their design which leaves a carbon fiber barrel that far exceeds the durability of a normal stainless barrel.

Bull/Heavy

Bull, or heavy, barrels will often be 1” in diameter with slight tapering along the gas block. These thick-walled behemoths can sustain no end to rapid and sustained firing, severe hot temperatures, and will consistently prove more accurate with less felt recoil than lighter designs.

Heavy barrels are normally used for larger calibers, but many states, like Maryland, require any semi-automatic rifle to have a heavy barrel. Barrett, Savage and Armalite are all manufacturers that utilize heavy barrels for some of their larger caliber rifles, like the Barrett Model 99 and the Armalite AR-50. Generally speaking, the heavier the barrel, the more accurate the rifle will be.

Match Grade

Match grade barrels are machined with far greater precision for much tighter tolerances and accuracy. Specifications are extremely precise, where entire length barrel variations of the bore cannot vary more than .0005” or less in some instances. Match grade barrels will attract shooters who require the utmost in precision at great distances. Wilson Combat, Christensen Arms, Falkor Defense, Nemo Arms and Barrett all utilize high-end match grade barrels for their long-range platforms.

Carbon Steel Barrels

Carbon steel is an alloy, which means it contains trace elements that determine durability and corrosion characteristics. 4150 CMV or “Mil-Spec,” is carbon steel with additional vanadium and carbon to provide for increased resilience in harsh environments or extreme heat temperatures (over 700ºF) where heavy firing is common. This type of material is very rugged and durable because it contains heat mitigation and abrasion resistant properties that stainless steel does not.

It’s important to note that “Mil-Spec” simply means that certain specifications have been met and is denoted for reasons of interchangeability, not military use only. As the amount of carbon in a steel alloy rises, the harder and stronger it gets. In addition, carbon steel barrels contain chrome or melonite treatment to extend the life and performance of the barrel.

Stainless Steel Barrels

A step up in accuracy for those who value precision, stainless steel barrels are easier to work with and allow for bore and filing to be accomplished at higher levels of consistency. While you get the highest degree of accuracy with stainless steel, you cannot punish this barrel with high volume shooting sessions, which can erode the throat of the barrel and kill accuracy; however, most shooters will never experience this problem with normal use. Stainless steel barrel can also be harder to maintain.

Chrome-Lined Barrels

Chrome-lined barrels are known for increased lifespan and durability.   This barrel provides protection against corrosion and heat, and will help maintain longer service utility. Chrome provides for a slippery surface that is hard and long-lasting, which will reduce rust and last through a prodigious amount of rounds.

In addition, a quality chrome-lined barrel will maintain accuracy out to 600 yards without issue. Barrett, Armalite, Smith & Wesson, DPMS, Colt and many more all employ chrome-lined barrels for some of their AR platforms. The chrome-lined barrel is the most common type of barrel used with AR-15 rifles.

Ferritic Nitrocarburizing-lined Barrels

Also known as melonite or nitride, ferretic nitrocarburizing is a case hardening process where the the inside and outside of the barrel is bathed in melonite/nitride to impart a very hard layer to the surface instead of coating for possibly better accuracy without additional cost. This type of treatment will provide improved lubricity, solidity, and will not add variation to the thickness of the bore.

AR-15 Barrels

There are many excellent barrels and barrel manufacturers to consider, as each barrel has its own unique advantage. Here are a few points to consider:

  • Barrel Length – This will ultimately determine the gun’s use, as a short barrel is typically preferred for maneuverability, and close quarter target acquisition. Longer barrels are typically used for increased distance and accuracy.
  • Barrel Profile – Understand the right marriage of strength, weight and durability for your intended use.
  • Material – Knowing what your firearm is going to be used for will ultimately determine what material your barrel should be. Consider stainless steel for precision and accuracy, and carbon steel for rugged resistance.

AR-15 Furniture & Accessories

Some call the AR-15 the Barbie Doll for men. What is nice about the AR-15 platform is that it has a very modular design and can be changed and upgraded with relative ease. After you get some time with your AR-15, you’ll be curious about what you can do to meet your specific purposes and make it run better.

You can easily replace buttstocks, grip, rail protectors and slings for full customization to meet your exact specifications.  There are hundreds of companies that now offer accessories for your AR-15. Sure Fire and Steiner weapon lights and laser sights are both exceptional choices if you are looking for something to “brighten” up your AR-15.

Handguards

Handguards provide protection from the barrel and are at the front of the weapon allowing for effective grip, maneuverability, and aim. The handguard is where you mount equipment like sights, grips and lights. Which handguard you choose will largely come down to personal preference and budget. Be it drop-in, attached to the receiver and barrel, or free float, connected only to the receiver, here are a few good drop-in and free float handguard options to consider:

Buttstocks

Buttstocks come in two types: fixed and adjustable. Fixed buttstocks are considered good for long-range accuracy because of inherent stability, while adjustable buttstocks provide for a greater degree of configurations to suit your specific purposes.

The buttstock should feel comfortable on your shoulder as you’re firing, as well as fit comfortably to the side of your face to form a cheek weld. This helps to ensure no slipping when you’re shouldering your rifle, which could be the difference in your shot. Note: It’s important to know your local and state laws as some types of buttstocks may not be legal for you to possess where you reside.

Here are a few good considerations:

Pistol Grip

Your grip can often be the most underrated part of your firearm. Pistol grips should fit comfortably in the palm of your hand and allow your fingers to feel relaxed as you reach for the safety and trigger. When it comes to pistol grips, you want one that gives you great control over your firearm during heavy shooting. There are many choices to consider in material, colors and pricing, as well as considering if your pistol grip is for recreation or competition. Here are a few excellent considerations:

Magazines

Magazines for AR-15s come in a variety of designs and your decision on what to get depends on what you plan to do with your rifle. Attention to such things as whether your rifle will accept your magazine loader, if it will easily insert and drop free when well loaded and empty, and how many rounds it holds will help you figure out which magazine will be the perfect match for your AR-15 needs. Most AR-15 magazines are mil-spec, meaning that you can use them across many different AR-15 platforms and manufacturers.

Note: It’s important to know your local and state laws as some magazines with capacities over 10 rounds may not be legal for you to possess where you reside.

Here are a few recommendations:

Receiver Types

Receivers provide housing for the operating parts of the fire control group, including the hammer, bolt or breechblock, and firing mechanism. The receiver is threaded at its forward position so that you can screw on the barrel.

In the case of the AR-15, there is an upper and lower receiver connected by two pins.  The upper receiver integrates the forestock, the charging handle, the forward assist, the gas operating system, the barrel, the bolt, and the bolt carrier assembly.

The lower receiver carries the magazine well, the pistol grip, buttstock, and the collective firing mechanism. Only the lower carries the serial number and is considered the legally controlled part of the firearm.

The overwhelming majority of AR-15 receivers are made from aluminum, and are manufactured in three different ways:

  • Forged receivers command the most respect as they are a combination of strength and value. Metallurgists confirm that the forged piece is strongest, claiming that as the material is shaped under pressure, its grain follows the same shape as the part, so the result is a continuous grain characteristic of strength.
  • Billet manufacturing of the receiver is accomplished by a CNC machine, which carves each receiver out of a single block of aluminum. This style of manufacturing produces the most aesthetic designs and fine lines; however, they are generally weaker, do less for performance and are more expensive.
  • Casting means that the receiver is formed using a mold. Molten aluminum is poured into the mold to form the shape. Once solidified, the casting is removed and finished on a CNC machine. If you are looking for the most cost-efficient option, a receiver cast in aluminum is your best bet.

AR-15 Receivers

There are many great manufacturers who make excellent quality upper and lower receivers for your AR-15. With regards to the lower receiver, here are some excellent recommendations:

If you are looking for a solid upper receiver, we would suggest:

  • Daniel Defense
  • Patriot Ordnance Factory
  • LWRC
  • Barrett Arms

AR-15 Types and Uses

  • Home Defense/Personal Protection. With its versatile design, a compact and lightweight AR-15 can be a go-to, especially when paired with a high capacity magazine. For home defense, most will choose a shorter barrel, best designed for close quarter situations. It would be best to stick with the standard caliber (.223/5.56), as well as look for a hollow point/soft point option.

Full metal jackets, or green tips, are not always the best option for home defense, as they can pass through several structures before stopping. The AR-15 is very easy to shoot, and at distances out to 300 yards, the AR will outperform the pistol. A good compact, lightweight option here would be a Smith & Wesson Sport II, Nemo Battle Light or a Falkor Defense Blitz.

  • Target Shooting. Basic principles of marksmanship and performance standards are improved with target practice shooting drills. Learn the capabilities of your AR-15 and apply this knowledge to figure out what else you might need to adjust about your rifle.
  • The AR-15 can serve as a hunting rifle because it is versatile, accurate and easily customizable. Many rifle manufacturers, like Remington and Savage, make AR-15 style hunting rifles like the R-15 predator rifle developed with the hunter in mind. Companies such as Nemo Arms, Falkor Defense and POF have developed AR-15/AR-10s with larger calibers for hunting big game.
  • Competition/ 3-Gun. Be it a 3-gun event or designated marksman rifle match, there are a few things to always consider with your AR-15 at this level of performance. As discussed earlier, for competitions that involve more movement, a lightweight or carbon fiber barrel can be extremely beneficial. For DMR competitions, a longer barrel is the easy choice.

To diminish variations that act upon the barrel every time you pull the trigger, a free-floated handguard is a must-have. Finding your natural point of aim is much easier when the rifle fits you, so get the right buttstock so that you are comfortable and can focus on accuracy.

Get a variable scope so that you are good to engage targets at different distances. If you are looking to get into competitive shooting, or are wanting to make an upgrade, now is the perfect time to spend a few extra bucks and upgrade your AR-15 with an adjustable trigger.

Purchasing an AR-15

There is a perfect AR-15 out there for you. Here are some excellent picks across all budgets for an AR-15 rifle:

Once you figure out your AR-15 rifle needs, the next step is purchasing your AR-15. Hinterland Outfitters is a licensed FFL dealer, and purchasing your firearms online is easy and can be shipped to another licensed gun dealer within the United States.

Conclusion

There is a lot of ground to cover in your expedition to getting that perfect AR-15, so be aware of all the criteria you want, including price point, and start shopping. And if you have questions, Hinterland Outfitters can answer them, so feel free to give us a call or send us a secure message via our contact page.

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