Temporary cavity created by free-flying projectiles propelled from a powder-actuated nail gun.

Nails and driving pins discharged from powder-actuated fastening tools bear some special ballistic characteristics. Compared to the usual pistol or revolver projectiles, the sectional density (S) of fastening pins is extremely high. The general prevailing opinion is that the kinetic energy delivered by fastening tools is not high enough to cause a temporary cavity.