The 5.56 projectile is designed to tumble and then fragment on the cannelure into multiple pieces. Velocity is the key, and happens to be why the M16 was designed with a 20" barrel for those higher velocities *see pic below*sunray said:Any varmint bullet is designed to have extreme expansion upon hitting the target. FMJ ball ammo isn't. 5.56 bullets were touted as being designed to tumble upon hitting, not breaking up. So the answer is, it depends on the bullet.




























