Yaw
Yaw is the angle between the nose of the projectile and the line of its trajectory.
Sporting Arms and Ammunition Manufacturers’ Institute (SAAMI) Glossary, http://www.saami.org/Glossary/. Yaw happens because a bullet on exiting a weapon may have residual contact with the barrel on one side, thus tending to distort its straight flight. This will temporarily be magnified because the bullet surface will not have been presented symmetrically to the aerodynamic effect of air friction. As a consequence, for a certain distance the bullet will have a vortex or spiralling action known as yaw. After a few metres the spin from the rifling stabilises the yaw until the bullet reaches its target. However yaw again happens when the bullet enters denser tissue.
Last updated on: 08 February 2014