AR-15 vs. M16

If you are the least bit familiar with guns, you have most likely heard the debate on whether the AR-15 and M16 are essentially the same gun. In reality, though they have a shared origin and a great deal in common, there are several key differences between the AR-15 and M16 rifles.

When you compare the M16 and the AR-15 more closely, you can clearly see the distinctions between these two famous firearms.

The History of the AR-15 and M16

The AR-15 is a gas-operated semi-automatic rifle commonly chambered for .223/5.56. It originated in 1956 and was created by Eugene Stoner, who worked for an American small arms company called ArmaLite. It features a lightweight design since it's largely constructed of aluminum and polymer. This design was revolutionary at the time, as the majority of firearms available in the 1950s were made with wood and steel.

The AR-15 was initially developed to be a military rifle, but ArmaLite had very limited success in selling it and later sold the design to Colt. In 1963, Colt was chosen by the U.S. military to produce an automatic rifle. The final product would be known as the M16 and become the standard-issue weapon for the Vietnam War, largely replacing the M14.

The M14 was a larger, fully automatic firearm chambered in .30-06, which generates a substantial amount of recoil. With the M16, Colt combined the lower weight and minimal recoil of the AR-15 with the fully automatic firing capability of the M14 and made a few minor changes to the former's internal components. After working through a few initial issues, the result was a success.

To capitalize on the appeal of the M16, Colt started mass-producing the semi-automatic AR-15 and made it available to law enforcement and the general public.

Nowadays, the AR-15 is one of the most popular rifles in America. Owners can modify almost every part of its internal structure, and there are over 10 million owned by civilians. The AR-15 is typically used for target practice, shooting competitions and varmint hunting.

M16 and AR-15 Differences

While these two famous firearms are closely related and appear extremely similar at first glance, they still have their differences in form and function. In comparing the AR-15 to the M16, most of the differences you'll see relate to the military rifle's full-auto capabilities.

• The lower parts kit: The AR-15 and the M16 use different lower parts kits. These kits include components such as the trigger, disconnector, safety selector lever and hammer. The main difference within these components is that the parts in an M16 lower work with an auto sear enabling the rifle to fire three-round bursts or in fully automatic.
• The lower receiver: The AR-15’s lower receiver is made with different internal dimensions to prevent it from accepting the M16’s auto sear.
• The bolt: In order for the M16 to provide its full-auto function, the bolt design is slightly different from that of the AR-15’s commercial bolt carrier group. The M16’s bolt carrier has extra mass at its rear, which interacts with the sear and helps to reduce the recoil endured when the gun is set to automatic.

What the M16 and AR-15 Have in Common

Since the M16 looks a lot like the Ar-15 and shares a lot of the same roots, they do have many similarities as well, with numerous components actually being interchangeable. The upper receivers of these two designs are functionally identical, and they share commonalities in the following parts:

• Barrel: One of the few steel parts in an AR-platform firearm, the barrel can be chambered for a variety of calibers. As a rule, the M16 fires 5.56 NATO. Many AR-15s are chambered for .223/5.56, which means they can use either the NATO rounds or their parent cartridge, the .223 Remington. However, those chambered specifically for the .223 should not be loaded with 5.56, as the two rounds generate different amounts of pressure.
• Gas block: The barrel of an AR-platform firearm has a small hole in the top to release gases when a round is fired. The gas block catches and directs those gases to cycle the bolt.
• Gas tube: The gas tube directs the hot gas back to the upper receiver in order to push the bolt backward and extract an empty casing.
• Charging handle: Also called the cocking handle or bolt handle, this device pulls the bolt carrier group back to cock the hammer.
• Firing pin: This essential piece pierces the primer on the cartridge once the hammer is released.

In the lower receiver of both the M16 and the AR-15, these components can be identical:

• Buttstock: Many civilians opt to fit their AR-15s with the classic military-style fixed stock.
• Buffer and buffer tube: The buffer system of the AR platform helps keep recoil to a minimum, which is part of what makes this design so appealing.
• Recoil spring: Located in the buffer tube, this spring is compressed when gas forces the bolt rearward. Once it reaches peak compression, it pushes the bolt forward again to load the next round.
• Pistol grip: This feature is attached to the lower receiver and enables the user to hold and fire the rifle comfortably.

For a more in-depth description and breakdown of AR-15 components, view our page on the anatomy of an AR-15.

How Do I Know Which One Is Right for Me?

The vast majority of people will be better served by buying an AR-15, as some states don't even allow private citizens to own an M16. Additionally, the gun was made unavailable for civilian purchase in 1986, which means you must find one manufactured before that ban. Since there are only so many eligible rifles on the market, they can come with a hefty price tag of $25,000 or more. Owning one of these rifles also requires one to file paperwork with the ATF and pay some additional fees.

Given the availability issues and legal requirements for owning an M16, it's not a purchase to be made lightly. However, if you're willing to invest the time, money and effort in acquiring one, it is possible to own this piece of history.

The AR-15, on the other hand, is legal in most states, although some areas do have stringent laws on how they can be configured. Unlike the M16, the AR-15 is still in production and can be found with ease. Still, if you want to pay homage to the military rifle, it's possible to build out an AR-15 with a few traditional M16-style parts for that legendary look without the associated paperwork and price tag.

Shop AR-15 Components at Wing Tactical

The AR-15 and the M16 come from the same roots, but they have very different applications. The civilian rifle is compatible with a vast number of aftermarket parts that allow shooters to put together the perfect gun for anything from home defense to ringing steel at hundreds of yards.

If you're looking to build your ideal AR-platform rifle, shop the selection of AR-15 parts and assemblies at Wing Tactical. We only sell products we would use ourselves, and with our high-quality selection of firearm components, we can provide you with everything you need to customize your AR-15 to your needs and wants. Feel free to contact our team for assistance finding what you need for your next AR-15 build.