The Bushmaster C15 Carbines are a unique hybridization of traditional AR-15 type features with space-age Carbon 15 composite molded receivers for light weight and rugged durability. The Carbon 15's lightweight 16" M4 profile barrel is made of chrome-lined chromemoly steel and includes an A2 flash suppressor pinned and welded in place to achieve 16" overall barrel length. The barrel and other critical steel parts are manganese-phosphate-finished for corrosion and rust protection. This model has a Carbon-15 composite lower receiver with an aluminum upper. The upper receiver is left open, allowing user flexibility in rear sight choices. It features a Mission First Tactical polymer quad rail with rail covers and a six-position stock assembly that fits a variety of shooters.