An AR-15 is a lightweight, modular rifle that fires 5.56x45mm NATO rounds. Designed by Armalite in the 1950s, the rifle has been used by militaries and law enforcement agencies around the world for nearly 60 years. The rifle’s popularity among civilians can be attributed to its modular design, which allows users to customize it to their needs, and its relatively low price tag. But how does an AR-15 work? Let’s examine the trigger squeeze to ejection process and explain how this popular rifle functions.
How It Started
Eugene Stoner, the designer of the first AR-15 design, wanted to create a semi-automatic rifle that allowed all movement on the same axis to avoid unneeded movement while firing the weapon. At the time, most semi-auto and full-auto firearms were driven by complex mechanical systems that created movement on many axes’, which caused the jarring of the weapon. This led to follow-on shots being less effective as they were either slightly off target or took a second to re-center your sites on the target.
To solve this problem, Eugene Stoner developed this system that used the gasses produced by a round being fired in the chamber to be collected and redirected to force the bolt carrier to the rear, allowing for the rifle’s cycling independent of the user’s input. This made for a much smoother weapon operation and allowed follow-up shots to be on target more frequently. While this system was cutting-edge, it has since become a standard for gas-operated firearm systems. Today, this system is still used by many modern firearms and is included in the most widely owned rifle: the AR-15.
When it comes to the actual functioning of an AR-15, that is done through the process dubbed the cycle of operation. This is done through 8 steps:
1. Firing
This is the first step, initiated by a squeeze of the trigger; this disengages the sear, which in turn frees the hammer and allows it to strike the firing pin. The firing pin strikes the primer on the casing of the round, which ignites the propellant. This propellant combusts in the chamber. This simultaneously expands the casing, sealing the breach, and creates back pressure that propels the projectile through the barrel and at your target.
2. Unlocking
Once the projectile passes through the barrel, the gas that built up, creating the back pressure to force the projectile forward, is now redirected backward in the gas block, traveling into the bolt carrier group (BCG) from the key, which will now force the BCG rearward, unlocking the bolt to it’s extended position.
3. Extracting
The extractor is a spring-loaded claw-like part; this snaps over the rim of the cartridge when it enters the chamber. When the BCG moves rearward, this removes the cartridge from the chamber.
4. Ejecting
On the reward motion of the BCG, the ejector uses its spring load to eject the cartridge, which spins out of the ejector and is deflected away from the shooter by the deflection panel on the exterior of the upper receiver.
5. Cocking
The rearward motion of the BCG also forces the hammer back down and locks it against the sear.
6. Feeding
Once the BCG reaches as far back as possible, it is forced forward by the buffer spring. On its forward motion, a new cartridge is stripped from the magazine.
7. Chambering
Once the round is stripped from the magazine, the forward motion seats the round in the chamber; this event is called “chambering.” The BCG and cartridge will be in place once this step is complete.
8. Locking
At the end of the forward motion of the BCG, the round and BCG are both in place; the bolt rotates, locking it in place, and creating a sealed chamber for the cycle to start over again on the next trigger squeeze.
As you can see, there is more to it than trigger squeeze to ejection. There are many steps in between, and it doesn’t end there. If you want to learn more about these rifles, the best way to do that is hands-on with your own. If you are new or experienced with firearms, a side-charge AR-15 might be the firearm for you, so check out our stock; you’ll see that what we have is right for you!