Rifles 101: A Beginner’s Guide to How an AR-15 Works

Every year, more than four million AR-15 rifles are manufactured and distributed throughout the U.S.

Have you been thinking about purchasing or building one yourself? If so, it’s important to have a clear understanding of the AR-15 complete assembly guide and how an AR-15 works before you get started.

Read on to learn everything you need to know about how an AR-15 works and their inner workings. You’ll also gain some insights into building your own rifle.

What Is an AR-15?

The AR-15 hashtag has millions of posts on Instagram and Twitter. Despite being so popular, though, a lot of people aren’t totally clear on what these rifles are and what separates them from other options on the market.

It also doesn’t help that there are a lot of myths out there surrounding the AR-15 that cause additional confusion. Here are some key facts you ought to know about AR-15 rifles before we get into the AR-15 complete assembly guide.

The Specifics of how an AR-15 works

• The AR-15 was designed by Eugene Stoner
• The “AR” is short for “Armalite rifle,” not “assault rifle” or “automatic rifle”
• AR-15s are not assault rifles; an assault rifle is a fully automatic machine gun
• AR-15s resemble military rifles like the M16; by law, though, they function like other semiautomatic sporting rifles (this means they only fire one round each time you pull the trigger)
• AR-15s are lauded for their accuracy, versatility, and reliability; they’re popular among target shooters and hunters
• In terms of power, an AR-15 is no different from any other hunting rifle
• AR-15s feature a modular platform that allows users to modify them and add different uppers (barrels and chambers) and lowers (stocks and grips)

Several Different Types of AR-15 Rifles

They’re differentiated based on their uppers (the top part of the rifle) and barrels.

A1s, for example, have a fixed carry handle and shell deflector. A2s are similar but are more often used in shooting competitions.

The A3 features a flat top, which makes it easier for you to attach additional pieces (such as a scope) to it. The AR-15 Flattop has a similar structure and comes in many configurations.

How an AR-15 Works?

When Stoner first developed the AR-15, his primary focus was the in-line concept. The idea behind this concept is that everything happens on the same axis, which extends from the muzzle to the stock.

The reason for this is to minimize shaking and force sent back against the shooter’s shoulder. Both of these issues can disturb the shooter’s point of aim and make it harder for them to take fast follow-up how an AR-15 works shot.

The Stoner System

AR-15s differ from other semiautomatic weapons because of the fact that all forces get applied on the same axis. They’re either direct straight forward or straight back.

The Stoner system makes this possible. This system involves a small part of the hot gases (the ones that propel the bullet) being diverted from the rifle’s barrel. They’re brought straight to the Bolt Carrier Group (or BCG for short) without any mechanisms intervening.

Locked Bolt Firing

AR-15s fire from a locked bolt. This means that, when cartridges are chambered, bolts close behind the case and rotate 15 degrees. After this happens, the lugs on the bolt head will engage protrusions on the barrel extension. This locks the bolt in place and allows it to withstand high pressure from powder combustion.

After the cartridge is fired, the bolt will rotate in the opposite direction and then get pulled backward. This allows for the extraction and ejection of the spent case. It also allows a fresh round to be chambered.

The AR-15 Complete Assembly Guide

Once the bullet passes the barrel’s gas port, a portion of the hot gases begins to flow into the gas tube. They enter the expansion chamber via the bolt carrier key and exert pressure on the surfaces inside the chamber. From here, two things happen:

• The bolt carrier, which is traveling rearward, causes the two holes that are drilled on its side to pass by the C rings on the tail of the bolt, which vents the hot gases
• The bolt carrier continues moving backward and is forced to rotate into an unlocked position; at the same time, the bullet leaves the barrel and the pressure drops

Bullet Carrier with the AR-15 complete assembly guide

After this happens, the bolt carrier continues moving backward and the bolt gets pulled back from the breech. The recoil spring then pushes the bolt carrier forward again, strips a fresh cartridge from the magazine, and chambers it. Via the cam slot and bolt lug interaction, the bolt gets rotated into the locked position once more.

Building Your Own AR-15

Are you interested in getting better acquainted with the AR-15? One of the best ways to do this is to build on yourself. Here are some steps to take if you want to build your own AR-15:

Decide What Type of AR-15 You Want to Build

Start by deciding what type of AR-15 you want to build. Do you prefer an A1 or A2, or would you rather have a flat-top option like the A3 or AR-15 Flattop?

An A1 or A2, both of which features a carry handle, is more portable and might be preferable for those who value convenience. If you plan on attaching a scope or anything else to your rifle, though, you’re better off choosing a flattop style instead.

Purchase Your Parts

Once you’ve chosen your ideal AR-15 model, it’s time to purchase your parts. Before you do this, you should check to see what the laws are in your state requiring building and owning a firearm like an AR-15. In New York, for example, you must register your “assault rifle” even though no federal registry exists for these weapons.

You can order parts for your AR-15 online, or you can visit a local store if you prefer to select them in-person. It’s perfectly legal for you to purchase these parts and build your weapon, as long as you abide by the specific regulations put in place in your state.

Set Up Your Workspace

Before getting started, make sure your workspace is prepped and ready for the building process. There are some key things you ought to keep in mind, including the following:

• Be sure to wear a shop apron and safety glasses to protect yourself from parts that might go pinging across the room when you start building
• Check that your workspace is well-lit and provides you with plenty of space to set out your parts and assemble them
• Lay a white sheet or other covering on the floor; that way, if pieces fall, it’ll be easier to spot them and they’ll be less likely to roll away

Here The AR-15 complete assembly guide

It’s important to check that you have all the right tools for assembling your rifle, too. This list includes the following:

• An action block
• A solder and adhesives
• Clamps and vises
• Stamps and punches
• Gunsmithing fixtures
• Screwdrivers
• Hammers
• Shooting glasses
• Wrenches

You’ll also want to make sure you have gun maintenance and cleaning mats handy, as well as utility brushes for cleaning your gun.

Assemble Your Parts

Now, it’s time for the fun part: assembling all of the pieces and putting your AR-15 together. Be sure to follow the specific instructions that come with your AR-15 kit. In general, though.

The process of the AR-15 complete assembly guide

• Installing the forward assist on the upper receiver
• Installing the ejection port cover assembly
• Assembling the bolt carrier assembly
• Assembling the charging handle assembly
• Installing the charging handle assembly and bolt carrier assembly into the upper receiver
• Installing the upper receiver into the action block, then tightening this into the vise
• Installing the barrel
• Installing the outer receiver nut and inner barrel retainer nut onto the barrel threads
• Installing the gas tube and gas block
• Installing the free float tube handguard

That’s it! Of course, it takes a lot longer when you’re actually putting all the pieces together. If you follow this order for the parts, though, you’ll have a fully functional AR-15 once the process is complete.

Choose Your Accessories

Once you’ve handled the AR-15 complete assembly guide, you might want to invest in some accessories to personalize your how an AR-15 works. You may choose to purchase a new AR 15 trigger, for example, or you may decide to buy a sling for easy carrying.

There are tons of accessories you can choose from for how an AR-15 works. Try not to bog it down with too many extras, though. This can make the transportation and firing process more difficult, especially when you’re first getting used to it.

Is an AR-15 Right for You?

Now that you know more about how an AR-15 works, are you ready to take the next step and build one for yourself? If you keep this information in mind the AR-15 complete assembly guide, you’ll have an easier time constructing a rifle that works well and looks impressive.

Don’t forget to check out some of the other gun-related resources on our site, too. We’ve got lots of articles on choosing the right weapons, shopping for accessories, and more.