What Are the Between the M-15 and AR-15?

AR-15 M-15 on Wood Background

The name “AR-15” has become synonymous with inexpensive, accurate and highly customizable.

This weapon has become a household name, even being called “America’s rifle” due to the sheer amount of rifles sold.

It’s useful for everything from hunting to self-defense and especially great for combat and survival situations.

But along with its popularity, also comes a wave of questions like “What makes the __-15 different from a regular AR-15?”

Let’s break down these differences, looking especially at the M-15 and AR-15.

Some History on the AR-15

In the early 1950s, the company Armalite designed the first semi-automatic version of an M-16 and dubbed it the AR-15.

One common misconception about the AR-15, is that the “AR” stands for “automatic rifle” or “assault rifle.” Neither of these are accurate. The “AR” in the name simply stands for “Armalite Rifle.”

In 1959, Colt purchased the AR-15 trademark from Armalite and just kept the name.

But in the ’70s, the trademark on the name “AR-15” expired, and other companies began mass-producing the popular style of the rifle.

There were so many nearly-identical designs of Armalite’s rifle, that “AR-15” became a generic term for any semi-automatic weapon styled after the Armalite original.

AR-15 and Ammo and Mag

The M-15

In 1994, the assault weapon ban specifically outlawed the “AR-15.” This led to many companies renaming their semi-auto rifles to avoid the stigma now attached to an AR.

Bushmaster came out with its “XM-15,” Smith & Wesson with its “M&P15,” and DPMS with the newly named “A15.”

Colt followed suit, and named their weapon the “M-15.” But, in all reality, it was just the same AR-15 with a different label carved in the aluminum.

So, the short of it is this: An M-15 IS an AR-15. In fact, it’s the version most closely designed after the original namesake.

AR-15 with optic

Characteristics of the M-15

Most guns that are thrown in the “AR-15” category have similar features. Here are some of the major characteristics of an M-15 that mirror most other AR’s:

But, probably the best-known characteristic of an AR is the potential for total customization. Nearly every component of this weapon can be replaced with whatever works best for you.

Ar-15 with mags and scope


So, the title of this article may be slightly deceiving because, in reality, an M-15 is an AR-15. And being one of the most popular weapons on the market, the AR-15 is truly “America’s rifle.”

Do you own an M-15? If so, what are your thoughts on it? Let us know in the comments down below!

About the Author:

Richard Douglas

Richard Douglas is a firearms expert and educator. His work has appeared on large publications like The National Interest, Daily Caller, American Shooting Journal, and more. In his free time, he reviews optics on his Scopes Field blog.
The Mission of Cheaper Than Dirt!'s blog, The Shooter's Log, is to provide information—not opinions—to our customers and the shooting community. We want you, our readers, to be able to make informed decisions. The information provided here does not represent the views of Cheaper Than Dirt!

Comments (9)

  1. @Harry,you can look by the tip of the barrel and it should be there,.223 and 5.56 are similar with different pressure,if it’s a 5.56 it can shoot both,if it’s a .223 it can only shoot .223,if it’s a .223 Wylde then it can shoot both as well.

  2. To Harry re: info on Bushmaster–You could go to the manufacturers website and search for the owners manual for the firearm you purchased. That manual should provide all the information you seek.


    Yeah I know you are being facetious but can you imagine a round that is about 2-1/4″ wide with a case length slightly over 1-3/4″ long? That would be a funny looking object On the other hand the M-79 grenade launcher 40mm x 102mm (1-5/8″ x 4″)had a round of similar diameter and an extremely low velocity. We used to joke a man can out run them because they are slow. I certainly wouldn’t want to try though

  4. I bought a Bushmaster from a friend, mostly because it was a great deal and he needed the money. I can.t find anything on it that tells me the caliber. It may in a place not easily seen. I was told that it was a .223. Any ideas of where to look? someone told me that .223 and 5.56 are the same and that both could be fired from the same weapon. Is that true? What would be the advantage of one vs. the other? Not as much of a comment as a question. Any answers or comments would be appreciated. Thanks

  5. I own several in four different calibers. With different uppers to change out. Every household should own one.

  6. Colts patents that they held on the AR-15 design expired in 1977 opening the opportunity for other companies to manufacture the rifles but not too use the Ar-15 model designation Colt continues to maintain the trade mark “AR-15” and had since 1967.

  7. After 24 years in the military, I came to intimately appreciate the simplistic structure and build of the AR15 as a personal weapon. As a life member of the NRA, I make it a point to practice safety first with all my weapons. The AR has been found to be highly customizable to practically any configuration one could desire. I have even introduced some friends to the world of AR ownership. Under my supervision, they gave birth to their very own by using my tools and equipment to mill and drill their very on lower from 80% lowers. Talk about pride in ownership! The first time they fired it the mile wide grin said it all! An AR is a highly customizable platform and shall forever remain America’s favorite weapon. Great for hunting, target, or home defense! I maintain both rifle and pistol platforms.

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