The SOCOM 16 was introduced in 2004, with the SOCOM II being introduced the following year; they are essentially the same except for their accessory rails. An uncommon variant called the SOCOM II Extended Cluster Rail features a longer top rail that extends over the ejection port to the stripper clip guide, allowing the operator to mount optics farther to the rear. It appears the SOCOM II was discontinued at the end of 2014. The SOCOM 16 CQB (close-quarters battle), a SOCOM 16 with a pistol grip and telescoping stock, was introduced in early 2016.