Hornady Critical Defense Rifle, 308 Winchester, 155 Grain, FlexTip, 20 Round Box 80920 Designed for short-range defensive situations, a new breed of FTX bullets are at the forefront of the Critical Defense Rifle ammunition line. The bullet's patented Flex Tip not only helps keep the nose cavity free from clogging as it passes through heavy clothing but also helps the bullet expand at low velocities.