SIG516: 30-round standard M4 mag, variable gas piston system- available in 7, 10, 14.5 and 18″ barrels. SIG SAUER was asked by the public to produce this gun, which has been improved with SIG accessories and variable gas system and gun handles identical to an AR system. SIG warranty reliability, but not all parts are made in the US. THe company is focusing on the international markets for LE and military. The SIG Academy is supporting a new AR-15 program to train operators with the new gun. No information is available on their site yet, but check out The Firearm Blog‘s post with more information and pictures and visit Tactical-Life.com for the official announcement from Sig Sauer soon!