In military terms: Short for Squad Automatic weapon, the standard squad-level light machine gun in the United States Military. Also known as the FN M249, this is a 5.56mm gas-operated weapon that has a cyclic fire rate of 725 rounds per minute (RPM), and a sustained fire rate of 85 RPM.
The SAW was developed by an United States Army-led Research & Development program in the late 70's to mid-80's, when the M-14 and M-16 assault rifles were unable to fill the all-important role of squad-level fire support, a gap created by the retirement of the BAR, or Browning Automatic Rifle, in the 1950s. The SAW fires the same 5.56x45mm M855 ball round and M856 tracer as the M-16A2, and can feed from both pre-loaded 200-round plastic boxes and 30-round M-16 magazines. This allows the support gunner in a squad to continue firing even after he has exhausted his basic load of 600 boxed rounds, using magazines taken from disabled riflemen, which can be a life-saving virtue in intense battle. In addition, if the SAW is disabled, its ammunition can be distributed to the riflemen, allowing for no round to go unfired.
The SAW can be wielded in one of several configurations: it can be fired as a rifle from the shoulder, wherein it offers the accuracy of a standard battle rifle; as an automatic carbine from the hip, wherein it offers fully-automatic fire in a close-quarters situation; as a squad base-of-fire weapon, fired prone off its included bipod, which gives a squad quick fire superiority in a fire-fight; or as a supported machine gun, where it is equipped with a tripod, T&E (transversal and elevation) mechanism, and spare barrel, and offers sustained and powerful fire for the purpose of engaging and killing enemy assets.
One SAW is contained in every Marine fire team, giving each 4-man unit powerful and self-contained combative capacity. It is, so far as I am aware, used in smaller numbers by the Army. The SAW adds to the fire-team the effectiveness of many additional riflemen, while retaining mobility and adding additional versatility.
The SAW weighs about 15.16 pounds- or 6.88 kilograms- with bipod and tools. It is 40.87 inches- or 103.81 centimeters- in length. A 200-round box magazine weighs 6.92 pounds- 3.14 kilograms- when fully loaded. As such, a SAW gunner's basic weapons load- weapon and three boxes of ammunition- is approximately 36 pounds, a weight more then offset by its effectiveness.
The SAW is an effective and powerful weapon, offering point-target accuracy out to an effective range of 800 meters, area-target accuracy out to 1000 meters, and a maximum range of 3600 meters. It is fired solely in full-automatic, but three-round bursts are used to ensure accuracy and controllability. It has no prospects of replacement, nor does it require any. It has served with distinction in many recent conflicts, including the wars in Afghanistan and Iraq.
See also: FN M249 Para.
Primary source: Federation of American Scientists - www.fas.org