Bulletproof vest standards and metarials

Bulletproof vest standards comparison

The most common standards for body armor are HOSDB and NIJ. HOSDB stands for Home Office Scientific Development Branch and NIJ stands for National Institute of Justice.

HOSDB has three levels of protection: HG1, HG2, and HG3. NIJ has six levels of protection: IIA, II, IIIA, III, IV, and Special Threats.

Here's a comparison of the two standards:

Standard    Protection Level    Test Round    Velocity
HOSDB HG1    Low    9mm FMJ RN    1175 fps
HOSDB HG2    Medium    .357 Magnum JSP    1250 fps
HOSDB HG3    High    7.62mm NATO FMJ    2750 fps
NIJ IIA                    Low    9mm FMJ RN    1225 fps
NIJ II                    Medium    .357 Magnum JSP    1395 fps
NIJ IIIA                    High    .44 Magnum SJHP    1400 fps
NIJ III                    High Rifle Protection Level 1    7.62mm FMJ lead core rifle ammunition (US military designation M80) with a specified mass of 9.6 g (147 gr) and a velocity of 847 m/s ± 9.1 m/s (2780 ft/s ± 30 ft/s)    
NIJ IV                    High Rifle Protection Level 2    .30 caliber armor-piercing bullets (US military designation M2 AP) with a specified mass of 10.8 g (166 gr) and a velocity of 878 m/s ± 9.1 m/s (2880 ft/s ± 30 ft/s)

Difference between NIJ and HOSDB

NIJ and HOSDB are two of the most common standards for body armor. NIJ tests for bigger calibers and higher man stopping power while HOSDB has focus on other threats such as 9 mm and .357 Magnum which is more common in England. They often work together on the same test methods of bullet and stab proof vests1. They use 2-3 standards that include Ballistic, Stab (edged blades), and Spike (pointed instruments).

Other standards:

There are other standards for body armor such as UL752 and ASTM. UL752 is a standard for bullet-resistant glass and other transparent armor systems. ASTM F1233 is a standard for testing the performance of police body armor.

Materials used in body armor
Some common materials used in body armor include Kevlar, steel, Polyethylene (PE), and ceramic. Kevlar and Polyethylene are primarily used to make soft body armor while steel and ceramics are used to make hard body armor.

Difference between hard and soft armor

Soft armor is typically lighter than hard armor and more comfortable against the body because of its flexibility. Soft body armor is made of a variety of densely woven materials made to stop bullets. It is made in a variety of different levels and protections. Soft armor is designed to stop handgun rounds but won’t stop rifle rounds unless it has hard plates in it.

Hard armor is often made of either steel alloy, Polymer (UHMWPE), or ceramic materials. These armor plates provide rifle-rated protection and have a lower backface deformation. Hard armor focuses its energy primarily on the tip of the bullet or the energy within the jacket itself, which causes it to spin.