Squad automatic weapon  A squad automatic weapon (SAW), also known as a section automatic weapon or light support weapon (LSW), is a fully automatic firearm used to give infantry squads or sections a man-portable source of fully automatic firepower. Weapons used in this role are often selective-fire rifles, usually fitted with a bipod and heavier barrel to perform as light machine guns. Squad automatic weapons usually fire the same cartridge as the assault rifles or battle rifles carried by other members of the unit. This reduces logistical requirements by making it only necessary to supply one type of ammunition to a unit. Squad automatic weapons are light enough to be operated by one person, as opposed to heavy machine guns such as the M2 Browning, which fire more powerful cartridges but require a crew to operate at full effectiveness. One of the first weapons used in this role was the Madsen machine gun. Although limited in today's terms, the Madsen was introduced in an era when the standard infantry rifle was a bolt-action repeater with fixed magazines reloaded with single rounds or chargers; sustained rapid fire with these weapons could be maintained only for very short periods of time. The Madsen was capable of fully automatic fire; despite having only limited magazine capacity, this was still more than that of the infantry rifle, and it was of the quick change detachable box magazine type. Though over 100 years old, the Madsen is still in limited use today. The standard machine guns of this era were of the Maxim type. Used by the British, Germans, and the Russians, these weapons were bulky, heavy, tripod-based, and water-cooled, they required a team of four men and, although excellent in the defence, were not suited to manoeuvre warfare. Another pioneering weapon in this role was the Browning Automatic Rifle (BAR). Introduced late in World War I, it remained in front-line service into the Vietnam War. Intended originally as an automatic rifle capable of delivering suppressing "walking fire" in the advance, the BAR came to be used in the light machine gun role. During World War II, as the importance of having a source of mobile automatic fire increased, the number of BARs in a unit also increased, until in some units it represented 1 in 4 of the weapons present in a squad. During its long service in the US military, it was pivotal in the evolution of U.S. fireteam tactics and doctrine that continues to the present day. Modern squad automatic weapons (such as the RPK and L86) are modified assault rifles or battle rifles (e.g. FN FAL 50.41 and M14A1) that may have increased ammunition capacity and heavier barrels to withstand continued fire and will almost always have a bipod.