Body Armor

Body Armor 101

Glossary
A

Angle of Incidence - The angle between the line of flight of the bullet and the perpendicular to the front surface of the backing material fixture.

Armor Carrier - A component of the armor sample or armor panel whose primary purpose is to retain the ballistic panel and provide a means of supporting and securing the armor garment to the user. These carriers are not generally ballistic resistant.

Armor Panel - The portion of an armor sample that generally consists of an external carrier and its internal ballistic protective component(s) (e.g., the front and back panels).

Armor Sample - One complete armor garment comprised of a single wraparound-style jacket, or a set (two) of front and back armor panels.

B

Backface Signature (BFS) - The depth of the depression made in the backing material, created by a non-penetrating projectile impact, measured from the plane defined by the front edge of the backing material fixture. For armor tested on built-up or curved backing material, the BFS is measured from the plane defined by the top edges of the depression or crater formed by the impact.

Backing Material - A homogenous block of non-hardening, oil base modeling clay, placed in contact with the back of the armor panel during ballistic testing.

Backing Material Fixture - A box fixture containing the backing material, typically comprised of a rigid frame constructed of wood or metal with a removable wooden back. The wooden back is not used during Ballistic Limit testing.

Baseline Ballistic Limit - The experimentally derived, statistically calculated impact velocity at which a projectile is expected to completely penetrate an armor component (sample, panel or ballistic panel) 50% of the time (V50). This velocity is also the velocity at which a projectile is expected to be stopped by the armor 50% of the time.

Ballistic Panel - The protective component of an armor sample or panel, primarily consisting of ballistic-resistant materials, usually enclosed in a nonremovable cover. The ballistic panel is normally retained within the armor sample or panel by a separate fabric carrier, and may be removable from the carrier.

C

Certification of Compliance - Manufacturer's affidavit (certification) that a production unit of body armor complies with all of the requirements of this standard for the labeled protection classification.

Compliance - NIJ approval, after successful ballistic performance testing to this standard, of a body armor model submitted to the NIJ Compliance Testing Program (CTP).

Compliance Test Group - A group of armor samples, either four, six or nine complete garments, submitted to the NIJ CTP for testing according to this standard.

D

Deformation - The maximum momentary displacement of the rear surface of an armor panel, caused by a fair hit that does not penetrate the armor, when the armor is in initial contact with the backing material.

F

Fair Hit - A bullet that impacts the armor sample or panel at an angle of incidence no greater than +/- 5 degrees from the intended angle of incidence, no closer to the edge of the ballistic panel than 76 mm (3.0 in) and no closer to a prior hit than 51 mm (2.0 in), at an impact velocity within +/- 9.1 m/s (30 ft/s) of the required reference test velocity.

Full Metal Jacketed Bullet (FMJ) - A bullet consisting of a lead core completely covered, except for the base, with copper alloy (approximately 90% copper and 10% zinc). "Total Metal Jacket (TMJ)," "Totally Enclosed Metal Case (TEMC)," and other commercial terminology for bullets with electro-deposited copper and copper alloy coatings have been tested and are considered comparable to Full Metal Jacketed (FMJ) bullets for this standard.

I

Insert - A removable or nonremovable unit of ballistic material that can be part of either the armor or ballistic panel, which is utilized to enhance the ballistic performance of an armor in a specific area (also known as "trauma packs" or "trauma plates").

J

Jacketed Hollow Point Bullet (JHP) - A bullet consisting of a lead core that has a hollow cavity or hole located in the nose of the bullet and is completely covered, except for the hollow point, with a copper alloy (approximately 90% copper and 10% zinc) jacket.

Jacketed Soft Point Bullet (JSP) - A lead bullet, also known as a Semi-Jacketed Soft Point (SJSP), completely covered, except for the point, with copper alloy (approximately 90% copper and 10% zinc) jacket.

L

Lead Bullet - A bullet made entirely of lead, which may be alloyed with hardening agents.

M

Minimum Velocity - The designated NIJ Standard-0101.04 reference impact velocity less 9.1 m/s (30 ft/s).

Model - A manufacturer's designation (name, number, or other description) that serves to uniquely identify a specific configuration of body armor based upon the details of the ballistic panel construction (i.e., the number of layers of one or more types of ballistic resistant material assembled in a specific manner or the manner in which the armor is held in place upon the torso).

NIJ verifies the ballistic resistance of a model based on ballistic testing of model samples in accordance with this standard. As an example, differences in stitching (e.g., box stitch versus quilt stitch) would make the ballistic panels different models. If a model of armor fails compliance testing, the manufacturer may never resubmit any armor under that model designation.

O

Obliquity - The same determination of striking condition as "angle of incidence."

P

Penetration - Complete Penetration (CP): The complete perforation of an armor sample or panel by a test bullet or by a fragment of the bullet or armor sample itself, as evidenced by the presence of that bullet or fragment (armor or bullet) in the backing material, or by a hole that passes through the armor and/or backing material.

Partial Penetration (PP): Any impact that is not a complete penetration is considered a partial penetration.

R

Reference Bullet Velocity - The designated impact velocity of NIJ Standard 0101.04 test threat ammunition, obtained using specified ANSI/SAAMI unvented velocity test barrels.

Retest - The NIJ CTP procedure for resolving ballistic performance issues with NIJ Standard 0101.04 compliant body armor models.

Round Nose Bullet (RN) - A bullet with a blunt or rounded nose. A bullet with a generally blunt or rounded nose or tip, which possesses a small, flat surface at the tip of the bullet, is also considered a round nose bullet for this standard.

S

Semi-Jacketed Hollow Point Bullet (SJHP) - A bullet consisting of a lead core with a copper alloy (approximately 90% copper and 10% zinc) jacket covering the base and bore riding surface (major diameter), which leaves some portion of the lead core exposed, thus forming a lead nose or tip, which has a hollow cavity or hole located in the nose or tip of the bullet.

Semi-Jacketed Soft Point Bullet (SJSP) - A bullet, also known as a Jacketed Soft Point (JSP), consisting of a lead core with a copper alloy (approximately 90% copper and 10% zinc) jacket covering the base and bore riding surface (major diameter), which leaves some portion of the lead core exposed, thus forming a lead nose or tip.

Strike Face - The surface of an armor sample or panel, designated by the manufacturer as the surface that should face the incoming ballistic threat.

W

Wear Face - The surface of an armor sample or panel, designated by the manufacturer, as the surface that should be worn against the body.

Y

Yaw - The angular deviation of the longitudinal axis of the projectile from its line of flight, measured as close to the target as practical.