AR Platform — Rifles, Pistols, Uppers & Lowers
The AR platform is the most modular, customizable, and widely supported firearm system in American history. Built around Eugene Stoner's original design and refined over six decades, the AR-15 and its variants allow shooters to configure a single lower receiver for virtually any application — from compact home defense carbines to long-range precision rifles — simply by swapping upper receiver assemblies.
Browse AR Platform by Type
- AR Rifles — Complete AR-15 and AR-10 rifles from Daniel Defense, Noveske, BCM, LWRC, and more. 5.56 NATO, .308, .300 BLK, and other calibers
- AR Pistols — Short-barreled AR pistol configurations in 9mm, 5.56, .300 Blackout, and pistol calibers from CMMG, Daniel Defense, POF, and more
- AR Uppers — Complete and stripped upper receiver assemblies. Swap calibers and configurations without purchasing a new rifle
- AR Lowers — Stripped and complete lower receivers. The starting point for every custom AR build
Popular AR Calibers
5.56 NATO / .223 Rem — Standard configuration. Widest ammunition selection and lowest cost • .300 Blackout — Optimized for suppressed use and short barrels • 6.5 Grendel — Extended effective range with excellent long-range ballistics • 7.62x39 — AK-caliber performance in an AR platform • .308 Win / 7.62 NATO — AR-10 pattern for long-range precision and hunting
All AR lower receivers require FFL transfer. Complete AR rifles and pistols also require FFL. Buyers must be 18+ for rifles, 21+ for pistols.
Frequently Asked Questions — AR Platform
What makes the AR platform so popular?
The AR platform's popularity comes from its modular design — a single lower receiver can be paired with any caliber upper assembly, allowing one firearm to serve multiple purposes. The platform has the largest aftermarket in firearms history, covering every imaginable component and accessory. Its ergonomics, accuracy, and the wide availability of affordable ammunition make it the most versatile semi-automatic rifle platform ever designed.
What is the difference between mil-spec and commercial AR components?
Mil-spec refers to components built to U.S. military specifications — the most common standard ensuring interchangeability between manufacturers. Commercial components may differ slightly in dimensions. For AR-15 builds, the most important mil-spec dimension is the buffer tube: mil-spec tubes have a slightly smaller diameter than commercial tubes. Stocks and buffers must match the tube specification. Most quality AR components are mil-spec.
Can I build my own AR-15?
Yes — building an AR-15 from components is legal in most states and does not require a manufacturer's license as long as it is for personal use and not for sale. You purchase a stripped lower receiver through an FFL dealer (this is the serialized component), then add components. The lower parts kit, upper assembly, and stock complete the build. Many shooters prefer custom builds to get exactly the specifications they want.