The AO-63 is a Soviet twin-barreled, AK-derived assault rifle chambered for the 5.45×39mm round. It was designed by Sergei Simonov and Peter Tkachev, and manufactured by TsNIITochMash. It uses a side-by-side barrel configuration, primarily to fire in two-round burst mode with a 0.01 second delay to increase ballistic performance.
The AO-63 assault rifle was used by the Spetsnaz during the Abakan trials in May/June 1986, in search of a more accurate alternative to replace the standard issue AK-74. It was described in the official report as being highly accurate as well as simple and reliable; despite its accuracy and performance, it was later dropped out of the competition for unknown reasons, with the AN-94 emerging victorious.
The AO-63 is a gas-operated, 5.45×39mm caliber, AK-derived twin-barreled assault rifle. The weapon has side by side barrels with the right barrel predominant, twin rotating bolts/gas pistons and ejects from both sides. The trigger group has a three-position selector on the right side of the receiver, the first is semi auto firing one barrel, the second in full auto firing both barrels with a 0.01 second delay, the third is unique as at first it fires a two-round burst then one barrel in 850 rounds/min full auto. The magazine is unusual as it has the main double column holding 30 rounds with a single column holding 15 rounds.