GC_UPC Colt Mfg LE6921CK-NHG LE6921 Upper Conversion Kit 223 Rem,5.56 NATO 14.50" $739.49 - show more like this Free on Guns, $9.99 Accessories, $14.99 Ammo Tombstone Tactical GC_UPC Colt Mfg LE6921CK-NHG LE6921 Upper Conversion Kit 223 Rem,5.56 NATO 14.50" $739.49 - show more like this Free shipping over $400 (Excludes Ammo) Gman Sport