Understanding the AR15

In 2020, roughly seven million Americans became first-time gun owners. Many of those joined the ranks of AR15 owners, one of the most popular styles of rifle in the United States. Yet, as popular as these rifles are, they are widely misunderstood, including by many of the people and politicians who want to restrict them or ban them outright. So, in the interest of setting the record straight, we thought we’d pass on a little knowledge about the ubiquitous AR15.

Let's start with the name.

Two Misunderstood Letters: A and R

You’ve probably heard or read a so-called firearms “expert” proclaim that the A and R in AR15 (also spelled with a dash: AR-15) stands for “assault rifle.” That’s wrong.

Or you may have heard this two-letter combination explained as being the initials for “automatic rifle.” Nope. That’s wrong, too.

The A-R combination in AR15 is merely an abbreviation for “ArmaLite Rifle,” ArmaLite being the company that developed the gun. The 15 is just the model number ArmaLite assigned to the rifle. So, the name AR15 does not give a nod to how this firearm could be used or how it functions. It simply means ArmaLite Rifle Model 15.

Just as most any firearm can be used for home defense or recreational shooting. How a firearm is used ultimately comes down to the operator and what they choose to do with it. But to label an entire style of rifle as an assault weapon is a gross simplification. AR15-style rifles can be used for a whole host of activities, including hunting, competitive shooting, recreational shooting, home defense, and, yes, military and law-enforcement applications.

It’s also wrong to think of an AR15 as an “automatic” weapon, because it isn’t one. The AR15 is a “semiautomatic”, not fully automatic.

Automatic vs Semiautomatic

You most likely heard members of the media or government talk about regulating or outlawing automatic weapons when what they’re actually referring to are semiautomatic firearms. There’s a big difference, and it all comes down to trigger pulls.

With a semiautomatic firearm, which an AR15 rifle is, every time you pull the trigger, a single round is fired. The escaping gas from the round cycles the weapon, ejecting the spent cartridge and feeding another live round from a spring-loaded magazine into the chamber so it’s ready to go. But you actually have to pull the trigger again to fire the next round because it’s strictly one round fired per trigger pull. If you pull the trigger (press it, actually) and hold it in place, only one round will fire. Another round will not fire until you relieve pressure on the trigger, allow it to reset, and then pull the trigger again.

With an automatic weapon, the firearm will continue to fire if you hold the trigger back—until you release the trigger or the gun runs out of ammunition or malfunctions. But you only need to pull the trigger and hold it once for rounds to continue to fire at a rapid rate. It’s not the ratio of one trigger pull for every round fired of a semiautomatic.

The full-auto version of the civilian AR15 is its military cousin known as the M16, which has been widely replaced by the M4 Carbine and its variants. Military and law-enforcement variants typically feature a selector switch that allows the weapon to be fired as a semiautomatic, fully automatic, or in three-round bursts. (You pull the trigger and three rounds fire, then reset the trigger and pull it again to fire another three-round burst.)

It’s worth pointing out that, while the semiautomatic AR15 is often erroneously singled out as an “automatic” firearm, it is by no means the only semiautomatic gun available to civilian consumers. Semiautomatic firearms exist in all shapes and sizes, including sporting rifles, hunting shotguns, and pistols.

A Brief History of the AR15

The history of how the AR15 came to be easily warrants an entire article of its own. But, in the interest of time and space, here’s an abbreviated history of how this iconic rifle became one of the most popular firearms in American history:

  • After World War II, in 1955, the U.S. Military decided to replace their standard-issue M1 Grand service rifle and solicited proposals from firearm manufacturers.
  • ArmaLite, with its design efforts headed by Eugene Stoner, designed and submitted the AR10 for consideration, a larger, heavier predecessor of the AR15 chambered in 7.62mm.
  • Although the U.S. Military liked much about the AR10, its barrel failed the “torture test,” and Springfield Armory’s T44 (later renamed the M-14) was selected and adopted in 1957.
  • The AR10’s design was subsequently used by Stoner to develop a smaller, lighter-weight rifle chambered in 5.56mm, which was named the AR15.
  • In 1959, ArmaLite, experiencing financial difficulties, sold the AR15 design to firearm giant Colt. Stoner joined Colt as a consultant, and Colt went on to produce the AR15 platform.
  • The AR15 soon found its way into military use in the 1960s and eventually became the select-fire M16, which ultimately became the primary service rifle in Vietnam.
  • After the Vietnam War, Colt began selling the semi-automatic AR15 to the civilian market.
  • Once AR15 patents expired, other gun manufacturers started producing and selling AR15-style rifles as well, which were sold to civilians until 1994, when the Federal Assault Weapons Ban made AR15-style rifles illegal for a decade, from 1994-2004.
  • Once the ban automatically expired, the AR15 grew steadily in popularity and eventually became one of the best-selling rifle styles in the country’s history.

AR15 Calibers

The vast majority of AR15 rifles are chambered in 5.56mm (.223). However, a wide array of other calibers, including larger hunting rounds, are available, depending on the rifle manufacturer. Most Daniel Defense AR15s are chambered in 5.56mm, but we also offer several popular AR15 rifles, such as the DDM4® 300 S, in 300 Blackout.

AR15 Gas Systems

As mentioned above, when you pull the trigger of a semiautomatic AR15, it should fire a round, extract and eject the spent cartridge, load a live round into the chamber, and reset the bolt carrier group so it’s ready to fire that next live round when you pull the trigger. This process is powered by the rifle’s gas system. There are two main types of gas systems used by AR15s: direct impingement and gas piston technology. Both work in a similar manner, with minor differences.

Direct impingement is the original gas system developed by Eugene Stoner. As the propellant gas from the exploding round pushes the bullet forward, part of that gas bleeds through a small hole (gas port) in the barrel and is channeled to the rear through a tube back to the bolt carrier group. The force of the gas pushes the bolt carrier group back and cycles the weapon.

Gas piston technology operates in a similar manner except instead of bleeding into a gas tube the gas is contained in a cylinder with a piston inside it. The propellant gas moves the piston rearward, and the piston pushes the bolt carrier group back instead of the “direct impingement” of the gas.

As with most any firearm discussion, be it barrels, rails, triggers, stocks, etc., you’ll find proponents and opponents of both styles of gas system. Daniel Defense favors direct impingement, which is why all of our AR15-style firearms feature this system. To learn more about the different length gas systems Daniel Defense uses and how they affect a firearm’s performance, check out this article on the best gas system for an AR15.

Anatomy of an AR15

M4A1 Exploded View

  1. Buttstock Assembly and Receiver Extension Assembly
  2. Upper Receiver Assembly
  3. Lower Receiver
  4. Handguard Assembly
  5. Barrel
  6. Muzzle Device
  7. Pistol Grip
  8. Magazine (If you want to be in the cool club, please refrain from calling this a 'clip'.)
  9. Front Sight
  10. Rear Sight

An AR15 is a very modular platform that can be broken down into a few key parts or groups, including:

  • Upper Receiver
    This is basically the top portion of an AR15 and contains the barrel, handguard (or rail system), bolt carrier group, charging handle, gas block and tube, and, if it has one, a forward assist. It attaches to the lower receiver to form a fully functional AR15 rifle.
  • Lower Receiver
    This group contains the trigger group, safety selector, buffer tube, bolt catch, magazine well and release button, and the rifle’s serial number.
  • Barrel
    The barrel plays a huge role in the functionality of an AR15. It is the rifled tube that the bullet travels through after the round is fired and will be a major factor in determining the rifles range and accuracy.
  • Muzzle Device
    A muzzle device is attached to the end of the barrel (at the muzzle) and can be one of three designs: a muzzle brake, a flash hider, or a compensator.
    • Muzzle Brakes are designed to primarily reduce recoil and secondarily help minimize muzzle rise.
    • Compensators are designed to primarily reduce muzzle rise and secondarily reduce recoil.
    • Flash Hiders are designed to reduce muzzle flash, which helps conceal a shooter’s position and provide a clearer line of sight that could be distorted by excessive flash.
  • Handguard/Rail
    A handguard/rail system provides a secure platform when firing the rifle as well as real estate for attaching accessories, such as optics, lights, sling attachments, etc. Accessory rails come in a wide array of designs featuring multiple attachment systems, including Picatinny, KeyMod, and M-LOK.
  • Trigger Group
    This consists primarily of the trigger and the hammer of the rifle and is what allows the firearm to fire a round. Having the right trigger pull weight, and exercising fundamental trigger control, play a huge role in making an accurate shot.
  • Buttstock & Pistol Grip
    The buttstock, typically adjustable, allows you to properly nest the rifle in your shoulder and better control and aim the firearm. The pistol grip, located behind the trigger, provides more control in maneuvering the rifle and helps place your trigger hand in a fundamentally sound firing position.

What to Look for in Buying an AR15

Buying (or building) an AR15 is a bit like buying a car. It all comes down to your needs, your budget, and how you want to use it. So, the question to ask is not necessarily “Which is the best AR15?” so much as it is “Which is the best AR15 for me?” Here are a few things you might consider:

  • Your Intended Purpose
    What you plan on doing with the rifle will, to a large extent, determine which features are most important to you. Do you plan on hunting with it? Is it for home protection? Competitive shooting? Answering these questions will help you narrow down many of the choices you need to make, including rifle caliber, barrel length and profile, overall rifle length, rifle weight, and more.
  • Ergonomics
    Does the rifle fit you? Is it comfortable to hold and shoot? Does your hand fit around the pistol grip? Is the handguard/rail uncomfortable to grip, and is there enough space for the accessories you intend to attach? Is the AR15 maneuverable enough for the activities you plan on using it for? If it’s an awkward fit, you may have a hard time hitting your target, and you probably won’t feel comfortable using the rifle.
  • Barrel
    The barrel profile, length, and twist rate all make a difference. A longer barrel typically helps with accuracy, and its profile will influence how heavy and durable it is. And the length of the barrel can also dictate how much paperwork you’ll have to do to own the AR15, whether you’ll pay more, or whether you can even legally own the rifle. Short-barreled rifles (SBRs), which includes any rifle with a barrel shorter than 16 inches, are regulated by the National Firearms Act, which means you’ll have to make sure you comply with all NFA rules and applicable laws to purchase one. Twist rate—the rate of spin created by the rifling inside the barrel—matters as well. A slower twist rate is generally better for shorter and lighter bullets, while faster twist rates tend to work better with longer heavier bullets. Finishes and coatings also tend to make barrels last longer, such as the Mil-Spec heavy phosphate finish Daniel Defense uses on the outside—and chrome lining it puts on the inside—of many of its barrels.
  • Trigger Group
    Do you want a heavy trigger or light break? The trigger is the conduit between you and the rifle that actually fires a round and puts the rifle into action, so you want a trigger that’s reliable and a break you’re comfortable with.
  • Materials & Components Used
    Which type of steel is used in the barrel and bolt carrier group? What type of aluminum is used for other parts: 6061 or 7075? What is the rail made of? What about the buttstock or even the finish on the rifle? The better the material used, the better the rifle should be.
  • Construction
    Is the receiver billet or forged from a solid piece of aluminum? Are the barrels Cold Hammer Forged like Daniel Defense’s? Does the manufacturer have a stringent quality-control process? How the rifle and its parts are made are just as important as what they’re made of.
  • The Manufacturer's Reputation
    One of the best ways to ensure you purchase a quality rifle is to purchase it from a quality manufacturer. Do they have a good reputation in the industry? What do their customer say about them? And do they stand behind their products? Buying a name brand is more than just having a logo or company name stamped or etched on the rifle. If it’s a reputable brand, like Daniel Defense, that name on the firearm means you can trust the manufacturer to meet the highest standards—and, if they don’t, you can trust that they’ll take appropriate action to make things right.

We know, it seems like a lot to digest. But try not to be overwhelmed. The AR15 is actually a fairly simple rifle, which is one of the reasons contributing to its overwhelming popularity. If there’s anything we here at Daniel Defense can do to make things less confusing or answer any questions, feel free to give us a call at 866-544-GUNS.