body armor

“Bulletproof” vests and similar garments are not, of course, proof against every bullet. More protection requires more weight and less comfort.

National Institute of Justice Standard 0101.03 sets standards for six body armor “threat levels”: I, IIA, II, IIIA, III, and IV, in increasing order of effectiveness. A parallel but slightly different set of standard “protection levels” is defined by the Personal Protective Armor Association; their levels run from A to E, with A offering the least protection. In both sets of standards the levels are defined in terms of rounds of ammunition: caliber, type and mass of the bullet, and muzzle velocity.

The NIJ advises all law enforcement officers to wear some type of body armor at all times. Many do not because they find it uncomfortable, although continued improvements in the aramid fiber from which the armor is made (almost always, Dupont's Kevlar) have made today's armor lighter and less bulky than the original product. Type II can be uncomfortable in hot, humid climates. Most people don't consider Type III-A suitable for routine wear in any climate, while Types III and IV are definitely primarily for wear in especially dangerous situations.

Below, for each type, are examples of rounds against which it is intended to offer protection:

Protection afforded by various types of body armor
I .22 long rifle high velocity, 40 grain round nose lead bullet, 1050 f/s +50/-0. .38 special, 158 grain round nose lead bullet, 850 f/s +50/-0.
II-A Low velocity .357 magnum and 9 mm, .45 mm auto.
II Higher velocity .357 magnum and 9 mm.
III-A .44 Magnum, submachine gun 9 mm, most handgun rounds.

None of the preceding types protect against rifle fire.

III high-powered rifle, 7.62 mm NATO rounds, 12-gauge rifled slug, 30 caliber full metal jacket.
IV armor-piercing rifle, 30 caliber.

According to the standard, every ballistic panel must bear a label that, among other information, gives the rated level of protection and the edition of the standard used to define the level.

resources

A pdf file this link goes to another website of the 1987 NIJ document, with full details.

Police Body Armor Standards and Testing, vol I this link goes to another website. A pdf file of an Office of Technology Assessment report from 1992, with a good discussion of the technology. Abolishing the OTA was one of the dumbest decisions Congress has ever made.

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