scope:

This standard is applicable to all ballistic resistant materials (armor) intended to provide protection against gunfire, with the exception of police body armor and ballistic helmets, which are the topic of individual NIJ performance standards [1,2]1. Many different types of armor are now available that range in ballistic resistance from those designed to protect against small-caliber handguns to those designed to protect against high-powered rifles. Ballistic resistant materials are used to fabricate portable ballistic shields, such as a ballistic clipboard for use by a police officer; to provide ballistic protection for fixed structures such as critical control rooms or guard stations; and to provide ballistic protection for the occupants of vehicles. The ballistic resistant materials used to fabricate armor include metals, ceramics, transparent glazing, fabric, and fabric-reinforced plastics; they are used separately or in combination, depending upon the intended threat protection.

The ballistic threat posed by a bullet depends, among other things, on its composition, shape, caliber, mass, and impact velocity. Because of the wide variety of cartridges available in a given caliber, and because of the existence of hand loads, armors that will defeat a standard test round may not defeat other loadings in the same caliber. For example, an armor that prevents penetration by a 357 Magnum test round may or may not defeat a 357 Magnum round with a higher velocity. Similarly, for identical striking velocities, nondeforming or armor-piercing rounds pose a significantly greater penetration threat than an equivalent lead core round of the same caliber. The test ammunitions specified in this standard represent common threats to the law enforcement community.