AR-15 Weapons Platform Family

Major AR Family Members

The AR-15 is the most commercially successful of the AR family. The M-16 is simply a select-fire version of the AR-15, as is the M-4.
The AR-10 is a 308 rifle based off of Eugene Stoner's earlier design.
Unrelated except in name, the AR-180 used a stamped receiver and shared no parts with the AR-15 as originally shipped. However, it seems that AR-15 FCG parts could in fact be used in it, just not in a configuration which resembled the original Armalite FCG. It also did not accept STANAG magazines. The AR-180 and AR-180B are usually what cause folks to exclaim that they've seen an AR-15 upper with a side-mounted charging handle. (Although American Spirit Arms does produce an AR-15 upper with a left-side charging handle)
The AR-180B (newer rifle) apparently shares more parts with the AR-15, and does accept STANAG magazines.

Generic Description of the AR Platform

The only rules which are actually adhered to by the AR platform are this:

The rifle has a lower receiver, which contains the trigger, stock, and grip. A magazine well is also included, but it might not be used, depending on how the rifle is configured. Certain variants of the AR system are designed with a sealed up magazine well, or NO magazine well (single-shot) in order to avoid legal issues with certain states. Others are designed for Glock, Uzi, or Colt 9mm SMG magazines (very similar to Uzi mags). However, the overwhelming majority of AR-15 lower receivers are set up for STANAG magazines. The standard reference example of a STANAG magazine is the venerable aluminum 30rd USGI M-16 magazine.

The rifle has an upper receiver, which contains the barrel, gas operating system, etc. In most cases, this is a gas-operated semi-automatic. In some cases, such as the 50 BMG upper receiver, the upper receiver uses a bolt.

Upper receiver choices include traditional semi-automatic uppers, single-shot bolt-action uppers, and a few exotic belt-fed uppers, in a plethora of different calibers. There are a number of them listed below; some bargains are referenced on specific pages. People are welcome to add more information for any of these calibers.

For a more general list of AR parts for sale, hit the AR-15 shopping page.

AR-family reference material

Buffer System Application Chart - where I dig into the differences between the various AR buffers and buffer springs.
308 AR Platform Receiver Compatibility Chart - this explains the differences between DPMS/KAC, Armalite, and other 308 AR-series rifles.

Building an AR-15

Preparing parts for a build
AR-15 Buttstocks - fixed and collapsible, choosing the one you want, and installing either one (with pictures)
Assembling an AR-15 Lower Receiver
- Different Magazine Release Assemblies
  - Installing a Standard Magazine Release Mechanism
  - Installing a Sporting Conversion Maglock (California, first-generation fixed mag compliance device)
  - Installing a B-15 Bullet Button (a California bullet button design which uses a Prince50 mag lock as its base)
- Installing the Bolt Catch Assembly
- Installing the Front Pivot Pin
- Installing a Collapsible Buttstock on an AR-15
- Installing a Fixed Buttstock on an AR-15
Installing a Front Sight Base on a virgin barrel
Installing a Phase 5 EBR (optional; replaces standard bolt catch)
Installing an Accu-Wedge (optional)
Installing a Receiver Rug (optional)
Iron Sights on the AR-15 platform
Analysis of a Rock River Arms 9mm

California Compliance Devices

Troubleshooting an AR-15

Favorite AR Configurations

Sean Newton's favorites

Available Calibers

-- SeanNewton - 28 Jan 2006

Thanks to Viras of Calguns for the Aeroprecision model number

Topic revision: r46 - 01 Sep 2012 - SeanNewton

Would this information help out someone you know? Click here to share it!