RIFLE: SIG SAUER MODEL SIG SAUER SIGM400, SERIAL NUMBER 20L216590, BLACK (MATTE), CASE NOT INCLUDED, SEMI - AUTOMATIC, 5.56, 18 Notes: *THESE PHOTOS ARE THE BEST STATEMENT OF CONDITION. PLEASE REVIEW THEM CAREFULLY BEFORE PURCHASING. The SIG M400 is a versatile direct-impingement AR-15 platform, most commonly found as the SIG M400 Tread, featuring a 18,16-inch or 11.5-inch barrel, 5.56 NATO caliber, and 1:7 or 1:8 twist rates. SIG SAUER SIG M400 ONE MAG SIG SAUER SCOPE TANGO-MSR 1-6X24