Semi-auto mid-length gas system operated •Lightweight profile 18" 4140 steel barrel w/corrosion resistant finish & 1:10" twist •9310 steel bolt •Chromed gas key bolt carrier & firing pin •Type III hard anodized 7075 T6 aluminum receiver •6.15 lbs. trigger pull •Ambidextrous safety selector & bolt release •Enhanced flash hider •7.71 lbs.