Ballistic Threats. Four ballistic threat levels are used in this
handbook, reflecting their severity level: (1) low, (2) medium, (3) high,
and (4) very high. These threats are summarized in Table 45.
Low-Severity Threat. The low-severity threat is the American
National Standards Institute (ANSI)/Underwriters Laboratories (UL) Medium-
Power Small Arms (MPSA) threat described in ANSI/UL 752. This threat
normally would be employed against facilities when the main objective of the
attacker is to persuade someone to turn over items of high value such as cash
or drugs. This threat also may be employed in a hostage situation.
Medium-Severity Threat. The medium-severity threat is the ANSI/UL
Super Power Small Arms (SPSA) threat described in ANSI/UL 752. This threat
normally would be employed when the attacker knows that ballistic-resistant
glazing is installed, e.g., teller cages.
High-Severity Threat. The high-severity threats are described in
the H.P White Laboratory, Inc., (HPW) HPW-TP-0501.00, Ballistic Resistance of
Structural Materials (Opaque and Transparent), Test Procedures and Acceptance
Threat. The very high-severity threat is the
Military Small Arms Multiple
Impact Threat (MIL-SAMIT) described in Naval
Civil Engineering Laboratory
(NCEL) Report CR 80.025. This threat is defined
as 25 rounds of 7.62-mm NATO
ball ammunition fired from an M-60 machine gun
at a range of 25 yards (22.9
Overview of Ballistic-Resistant Materials and Defeat Mechanisms.
Ballistic-resistant materials include various commercially available
structural materials, special armor materials, and composites. These
materials are used to improve the ballistic resistance of walls, roofs,
ceilings, windows, and doors of structures to protect the contents and the
occupants against ballistic attack. Ballistic-resistant materials are
divided into two categories: (1) transparent armor, and (2) opaque armor.
These are discussed below.
Ballistic Resistance. The term "ballistic resistance" denotes
protection against complete penetration, passage of projectiles, or
spallation of the protective material to the degree that injury would be
caused to a person standing directly behind the bullet-resisting barrier.
This definition is set forth in the ANSI/UL Standard for Bullet-Resisting
Equipment, ANSI/UL 752. The ANSI/UL definition of bullet-resisting glazing
material specifies that there should be no penetration of the projectile,
fragments of the projectile, or fragments of the glazing assembly with
sufficient force to embed into or damage 1/8-inch (3-mm)-thick corrugated
cardboard indicators placed a distance of 18 inches (450 mm) behind the
protected side of the test sample. This conforms to the protection ballistic
limit described in par. 6.2.3.