What Is the Difference Between the M-14 & the M-21?

History

• The M14 was developed as an adaptation of the M1 rifle that saw widespread use in World War II. For 11 years, from 1959 to 1970, it was the standard rifle of the United States Army, although it is not generally in common front-line use today. By contrast, the M21 entered service in 1969, and has gone through several upgrades. Today, the M25 --- another M14 variant like the M21 --- offers yet a third option for military snipers, alongside the M24, which is not part of the M14 family.

Role

• The M14 was intended as a standard issue rifle, but its heavy weight and length counted against it in the dense of jungle of Vietnam, and the powerful cartridge was less useful in areas of low visibility. By the end of the Vietnam war, the M14 had been nearly completely supplanted by the M16, a lightweight "assault rifle." The M21, however, is a sniper rifle --- intended for use in roles where rapid fire and quick target acquisition are lower priorities.

Components

• Initially, the M21 was simply an M14 with a variable 3x to 9x scope mounted to it. As it proved its worth as a sniper rifle, however, other changes were made to the basic components of the weapon. It has a stiffened stock intended to increase accuracy, and the receiver has been modified so that the weapon cannot be fired in fully automatic mode. The M14 has a fire selector switch, permitting it to be fired fully automatically like the M1918 Browning Automatic Rifle (BAR); both the M14 and M21, like the BAR, have a 20-round magazine.

Ammunition

• Part of the high accuracy associated with the M21 rifle comes from its ammunition, specially formulated match grade ammunition manufactured to extremely high tolerances. Specifically, although both the M14 and the M21 are chambered for the 7.62x51mm NATO round, the M21 is designed for use with the M118 cartridge, not the more common M80 cartridge. In emergencies, the M80 can be used in the M21 without damaging the rifle, but its scope was designed for use with the properties of the M118 and its accuracy is liable to suffer.