Today we are going to tackle the infamous AR. There is only one true meaning for this and I’ll cover what it mean and perhaps why there is confusion about its meaning, besides any political posturing it may be used for.
The M1 was the weapon of choice in WWII along with a few others like the Thompson’s Machine Gun (Tommy gun.) The times were changing and the military wanted something better. After a few different firearms in the Korean War didn’t do exactly what they wanted, they put out another request for mass produced firearms and got the AR10 chambered in 7.62x51mm.
The AR10 was deemed too unreliable on full auto so the AR15 chambered in .223 was developed. ArmaLite couldn’t get the government to accept their design so they sold it to Colt and it was finally accepted as the M16.
The original AR-15 (which is supposedly Eugene Stoner’s 15th design for ArmaLite) was a select fire design that could be set to automatic fire. This classified the firearm as an automatic rifle and this is likely where any confusion comes from. However, this does not mean that AR stand for automatic rifle. It is an abbreviation of the company ArmaLite that held the design for the rifle.
Civilian models of the AR-15 are not produced with the automatic fire capabilities. In fact, the only legal way to obtain an automatic fire AR-15 is by bidding on a pre-1986 model that would go through the ATF and DOJ.
Here is a Link that explains how a civilian model works.