During the 1950s, Armalite's AR-10 proved to not be the breakthrough they were hoping for, despite the design's superiority to other battle rifles of the era. As the Vietnam War began to escalate, it became clear that the M14 rifle used by the United States was outclassed by the AK-47 assault rifle and its variants in service with North Vietnamese forces. Army tests were biased towards the M14, and out of frustration, the AR-15 design was sold to Colt's Manufacturing Company, which produced it as the Colt Armalite AR-15 in .223 Remington. Eventually, the AR-15s overwhelming merits were recognised, and a modified version named the M16 was adopted for service.
In the mid-1960s, AR-15s are sought after for their lightweight firepower and automatic controllability. Special forces are especially fond of these weapons. As time passes, more and more countries will adopt varieties of the AR-15 rifle, following the U.S.' example.