a modified bolt, carrier and trigger assembly that will only allow semi-automatic fire. The rifle also has a slightly different optical sight that features a reticule with a fine dot in the centre of the aiming circle, allowing for more precise aiming. The Steyr AUG P Special Receiver is similar to the AUG P but features a STANAG scope mount system on top of the receiver. The Steyr AUG SA is a semi-automatic only variant of the AUG A1; built for civilian use and import to the US before being banned from importation in 1989. The Steyr AUG Z is a semi-automatic only variant in compliance with Austrian weapon laws, somewhat similar to the AUG A2 but lacking the quick detachable barrels and is unable to accept the trigger group from the assault rifles. It is intended primarily for civilian use. The Steyr AUG Z Sport is a semi-automatic only variant, somewhat similar to the AUG Z for use in sport shooting approved by the BKA in Germany. This variant has a special handguard without the typical front grip. The Steyr AUG Z A3 is a semi-automatic only variant of the AUG Z similar to the AUG A3, and was introduced in 2010. The Steyr AUG Z A3 9mm is a semi-automatic only 9×19mm Parabellum variant of the AUG Z A3. The Steyr AUG Z A3 SE is a semi-automatic only variant of the AUG Z similar to the AUG A3 SF. The Steyr USR is an AUG A2 modified to meet the former Federal Assault Weapons Ban (AWB) (or Public Safety and Recreational Firearms Use Protection Act) regulations. The primary difference is the omission of the flash hider. The Steyr AUG A3 SA USA is a semi-automatic only variant of the AUG A3 with a barrel, made available for the U.S. civilian market in April 2009. The Steyr AUG A3 SA NATO: Similar to the AUG A3 SA USA but uses a right-hand-only, NATO STANAG magazine stock assembly. The Steyr AUG A3 M1 is a semi-automatic only variant of the AUG A3 SF with a detachable optical sight which can be replaced with MIL-STD-1913 rails, manufactured in the US by Steyr Arms since October 2014. The Steyr AUG SPR is a straight pull only configuration, somewhat similar to the AUG A2 and is intended primarily for civilian use. AUG clones The STG-556 was introduced at the 2007 SHOT Show,