WHAT’S IN A NAME?
An entire article could be written about this, but in a nutshell, there are two patterns of large-receiver ARs: the Eugene Stoner-designed AR-10 produced only by Armalite, and the SR-25 (Stoner Rifle) developed by Eugene Stoner with Knights Armament Corporation (KAC).
Due largely to increased parts commonality with the AR-15, the SR-25 type took off in popularity and became the design all current manufacturers would base their designs on—most notably in the civilian market, the DPMS LR-series. With no MIL-SPEC standard, many manufacturers have varying degrees of design differences with the SR-25.
The one thing that has seen some semblance of standardization is the magazine. There are a few that use other styles, but most makers use SR-25compatible magazines. These magazines are generally labeled as being compatible with LR/SR or M110 (the military designation for the KAC sniper/designated marksman rifle) systems. Other mag makers just call them 7.62 or .308 AR mags.
The dilemma for this article is what to call these magazines as a generalized group. “LR/SR-25compatible magazines” would be the most accurate; however, most shooters know the rifle as the AR-10, not the LR/SR-25. Nevertheless, calling it an AR-10 magazine isn’t technically correct and could lead to confusion when purchasing magazines. The reason is that commercial magazines aren’t marked as AR-10, except for those made specific to the Armalite.
Just to clarify and to avoid confusion, this article refers to the large-receiver AR as an “AR-10,” because that’s what most shooters know it as, but we’re referring to magazines for the LR/SR-25 pattern rifle.
Just know that when purchasing magazines, unless you own the actual Armalight AR-10 pattern rifle, most magazines will be compatible with your rifle. Be sure to read the packaging to confirm.