|Calibre:||5.56 × 45 mm NATO|
|Barrel length:||508 mm|
|Overall length:||1000 mm|
The aluminium and plastic AR15 (M16 is its military designation) was designed by Eugene Stoner in response to a requirement for a new lightweight U.S. infantry rifle, initially losing out to the more conservative wood and steel M14 design. However, it went on to supplement and then replace that weapon through the 1960s.
The M16A1 was the definitive production variant, addressing some of the early problems experienced in Vietnam. The M16 introduced the 5.56 × 45 mm NATO round, a high-velocity but lightweight round that was thought to be the best compromise between effectiveness, weight, and felt recoil (especially in fully automatic mode).
Both weapon and round are in widespread service with various countries today, along with an increasing number of new variants upon Stoner’s original 7.62 mm AR10 design of 1956.