Whether you’re new to firearms, shopping for that first AR, or a veteran shooter, there’s always more to learn. This introductory piece is geared toward those wanting to learn the basics of AR-platform rifles. 

What is an AR-15? How about an AR-10? Is one better? When would you choose one over the other? We’ll answer those questions and get you on the road to mastering the field of modern sporting rifles. 

Table of Contents

What is an AR? 
The AR-15
The AR-10
Ideal Applications
Final Thoughts

What is an AR?

Let’s begin with what an AR is not. Contrary to uninformed popular belief, the letters do not stand for assault rifle or automatic rifle. In fact, the initials refer to the company that created the platform, as in “ArmaLite rifle.” AR, then, defines the basic design. 

Though ARs get an undeserved and inaccurate bad rap because they resemble military arms, the AR-style rifles for sale on the open market are quite standard semi-automatic systems. In the civilian world, an AR is a semi-automatic, modular, customizable centerfire rifle known to most as a modern sporting rifle (MSR). 

At its most basic, each rifle comprises an upper and lower. The former includes the bolt carrier group, barrel, forend, and action system. The latter includes the receiver, trigger group, and buttstock unit. These parts, by and large, can be changed, upgraded, and modified with others from its family. 

Speaking of families, the AR platform is further broken down into two main centerfire rifle categories: AR-15 and AR-10. 

Related: How the AR-15 Became America’s Rifle

The AR-15


Ruger AR-556 AR-15 rifle
The Ruger AR-556 is a popular rifle built on the AR-15 platform. (Photo: Chris Eger/Guns.com)

The AR-15 is the gold standard for what most consider an AR. The 15 is more lightweight, lower recoil, and by far the most common. The standard chambering is 5.56x45mm, also known as 5.56 NATO – and similar to the .223 Remington

5.56 NATO ammo vs .223 Remington
5.56 NATO cartridges on the left versus .223 Rem on the right. (Photos: Guns.com)


Related: .223 Rem vs 5.56 NATO – What's the Real Difference?

The standard magazine capacity is 30 rounds, though smaller and larger mags are available. The customary barrel lengths are 16 to 18 inches, culminating with a flash hider, though many other options exist. An adjustable, six-position buttstock and a pistol grip are standard equipment. 

The AR-15 is a more compact platform with a shorter action than the AR-10. Most AR-15 uppers can be swapped out from 5.56 to other similar chamberings, including 6.5 Grendel, 300 AAC Blackout, .204 Ruger, .350 Legend, and even .410 shotgun or rimfire .22 LR. 

Related: How to Build an AR-15 – 10 Easy Steps With Videos

The AR-10


Ruger SFAR AR-10 Rifle
Ruger's SFAR AR-10 rifle is a popular entry to the AR-10 platform. (Photo: Guns.com)

Think of the AR-10 as the AR-15’s bigger brother. It fires larger calibers and reaches greater distances. That means a heavier firearm and, in most cases, significantly increased recoil. The standard AR-10 chambering is 7.62x51mm or 7.62 NATO, and blood kin to the .308 Winchester

Barrels are commonly found in 18- to 20-inch lengths, though 16- to 26-inchers are out there. The typical magazine capacity is 20 rounds, with lesser capacity much more common than greater. Like the AR-15, the 10 usually uses adjustable and modular furniture. 

With its slightly longer action and beefier components, the AR-10 can accommodate uppers tailored for rounds like .243 Winchester, 6.5 Creedmoor, .338 Federal, and even .300 Winchester Magnum. Even shotgunners can get on board, as the AR-12 is a 12-gauge shotgun with roots in AR-10 design. 

Related: Best Beginner AR-10 Rifles

Ideal Applications

While the AR-15 and AR-10 are often used for both hunting and defensive applications, that’s where they find more defined roles. Because it fires smaller, less potent rounds, the AR-15 is generally a closer range, smaller game selection. 

Firing much more powerful rounds, but with increased recoil, the AR-10 is better suited to larger game and longer distances. Hunting Coyotes? AR-15. Hunting big game? AR-10. Home Defense? AR-15. Long Range work? AR-10. 

The AR-15 is by far the most popular, in large part due to being more affordable and accessible. Of the two, it is also more standardized in terms of modularity. Most milspec components are interchangeable from one AR-15 to another across the majority of manufacturers. 

While AR-10s are also incredibly modular, buyers must ensure components will interchange before swapping uppers, lowers, buffers, and other key parts.

Related: CMMG Mk4 Resolute in .350 Legend

Final Thoughts

The AR-15 and AR-10 are both modern sporting rifles that serve multiple purposes. Owners of one often find themselves wanting to add the other to their collection as well, because the AR platform is user-friendly, practical, and comfortable for a wide range of shooters. 

From hunting to defense, competition shooting to tactical work, and everything in between, these customizable, adjustable, durable rifles have endeared themselves to millions of shooters around the world. 

revolver barrel loading graphic