The AR-15. Armalite Rifle, Design 15, designed in 1957 to be fielded as a lightweight rifle for US Air Force security forces, has become one of the most prolific and misunderstood rifles in the modern world. Love it or hate it, the AR-15 is definitely here to stay. Itself a scaled down version of the AR-10, the AR-15 is, in its original guise, an extremely lightweight, handy, portable, accurate rifle which is capable of accuracy far beyond what many think possible out of it, and it is typically chambered for a lightweight cartridge with little recoil that is more than capable of doing a vast number of tasks when employed correctly by competent shooters.
Designed by Eugene Stoner, Jim Sullivan, and Bob Fremont in the early 1950s, the original AR-10 was adopted by a small handful of countries. It certainly had a unique appearance, and quite a lot of interesting features. Here you can see a very old commercial showing an AR-10 and when you compare it against much of the competition of its period (the FN FAL, the H&K G3, and what would later become the US M14), you can definitely see why it may raise a few eyebrows and pique some interest.
It was later scaled down to handle the 5.56 cartridge, which it would stay in for the majority of its development since then. It was introduced with US forces in the Vietnam War of the 1960s, and many of the issues it would see would go on to haunt it to this day. I shared an article about that very topic, which you can read here.
From the introduction of the Colt 601 with the Air Force and subsequent rapid development cycle that would result in the M16A1 rifle, the M16 has seen quite a lot of developments and derivations. From it, the HK416/417 weapons were developed, as well as the Canadian C7/C8/IUR rifles. Many other countries have adopted various systems based on the rifle using an external piston, and still more have been designed and developed for the civilian market. Along side the AK, it is one of the most prolific weapons in the world.
Cycle of Operations
The genius of the AR-15 rifle is three-fold: Its lightweight construction makes it very easy to carry, its inline recoil system makes it incredibly controllable, both in semi-automatic and full automatic fire, and its hybrid direct impingement/internal piston operating mechanism creates few moving parts in the system, and centralized them in one place, simplifying and stabilizing the weapon during firing.
If you’d like to see a video demonstrating the cycle of operations, you can watch this original training film, which explains it beautifully.
Otherwise, I will give a much simplified explanation here. Prepare yourself for…..
The Simplest Explanation of How ARs Work You’ll Ever Read
- The bolt being in the closed and locked state, the trigger is squeezed.
- The hammer falls and strikes the firing pin
- Expanding gas from the firing cartridge is redirected through the gas port and tube in to the gas key of the bolt carrier, which guides it in to an expansion chamber inside the bolt carrier group
- The gas expands, pushing against the bolt and forcing it to unlock and move rearward under recoil and residual pressure
- The bolt moves to the rear, extracting and ejecting the spent case
- The rearward action of the bolt carrier pushes the hammer back until the disconnector grabs the back of the hammer, preventing it from falling again
- The buffer and buffer spring push the bolt carrier back forward, picking up a fresh round from the magazine
- The bolt finishes its forward stroke and rotates in to battery, ready for the next shot
- The shooter releases the trigger until the disconnector releases the hammer and it moves on to the sear, ready for the next shot.
I hope this has been enlightening, and helped giving you an idea of where the modern AR-15 came from and how it functions. All photos either came from Wikipedia or were in the public domain. If you have any questions or concerns, or you wish to be credited for a specific photo, please email the webmaster through the Contact Us page.
~ The Pennsylvania Rifleman