(Luftwaffe) in 1941. Another German design that used selective fire was the StG 44 that was the first of its kind to see major deployment and is considered by many historians to be the first modern assault rifle. "The principle of this weapon -- the reduction of muzzle impulse to get useful automatic fire within actual ranges of combat -- was probably the most important advance in small arms since the invention of smokeless powder." The selective-fire function was later seen in the Russian AK-47 (designed in 1946), the Belgian FN FAL (designed 1947-53) the British EM-2 (designed in 1948), and the U.S. AR-10 (designed in 1957) and its AR derivatives. Design Selective-fire weapons, by definition, have a semi-automatic mode, where the weapon automatically reloads the chamber after each fired round, but requires the trigger be released and pulled again before firing the next round. This allows for rapid and (in theory) aimed fire. In some weapons, the selection is between different rates of automatic fire and/or varying burst limiters. The selection is often by a small rotating switch often integrated with the safety catch or a switch separate from the safety, as in the British SA80 family. Another method is a weighted trigger, such as the Steyr AUG, which will fire a single shot when 4.0 - 7.1 kg (8.8 – 15.4 lbs.) of weight is exerted on the trigger, and then become fully automatic when over 7.1 kg (15.4 lbs.) of weight is applied. This is useful for emergency situations where a rapid volley of rounds is more effective for suppressing a close enemy rather than a single-round burst. Some selective-fire weapons offer a burst mode as the second option, where each pull of the trigger automatically fires a predetermined number of rounds (generally two or three), but will not fire any more until the trigger is released and pulled again. The current U.S. standard assault rifle, the M16A4, and the M4 carbine variant of this rifle fire a maximum of three rounds with each pull of the trigger in burst mode. In this design, it retains the count of previously fired rounds and may fire fewer than three rounds. Other designs reset the count with each trigger pull, allowing a uniform three-round burst as long as rounds remain. A common version of the Heckler & Koch MP5 submachine gun (which is widely used by SWAT teams and