The first squad automatic weapon used by the US Army was the French Mle 1915 Chauchat, which was the primary LMG or automatic rifle for troops in the American Expeditionary Force in World War One. At that time, the Chauchat was a company-level weapon assigned where the company commander thought best. In World War Two, the Chauchat had been replaced by the BAR, and one BAR gunner was in each 12-man rifle platoon. The BAR was treated like a heavy rifle though, and not like a support weapon as light machine guns were in most other armies.

After Korea the value of the BAR was given more consideration and two were put in each squad instead of one, but the M14 replaced the BAR before it could gain any greater doctrinal importance. The M14 was intended to basically go back to the World War Two notion of every man equipped with a very capable individual weapon, and the squad having excellent flexibility and mobility by not being burdened with a supporting machine gun. The M60 machine guns were once again treated as higher-level weapons, to be attached to rifle squads as needed.

After Vietnam, experiments with different unit organization - and with the Stoner 63 machine guns - led to the decision that a machine gun needed to be incorporated into the rifle squad. This led to the request for what became the M249 Squad Automatic Weapon, and its adoption in the 1980s. At last, the American rifle squad included an organic supporting machine gun.

Today, the USMC is once again going back to the earlier model with every rifleman carrying the same weapon, now an M27 Individual Automatic Rifle. The Army may also change its organizational structure with the new XM7 and XM250 rifle and machine gun, but only time will tell...