Shop › BALLISTIC BBL 5.56 16" M4 1/7 BALLISTIC BBL 5.56 16" M4 1/7 $161.50 Ballistic Advantage Modern M4 Barrel, 556NATO, 16", 1:7 Twist BABL556014M Quantity: Add To Cart Added! Ballistic Advantage Modern M4 Barrel, 556NATO, 16", 1:7 Twist BABL556014M