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***Technology Assessment Program***

**NIJ Standard for Ballistic Helmets**

Supersedes NILECJ-STD-0106.00 dated September 1975

***A Voluntary National Standard Promulgated by the***

***National Institute of Justice***

**December 1981**

**U.S. DEPARTMENT OF JUSTICE**

**National Institute of Justice**

**JAMES L. UNDERWOOD**

**Acting Director**

[]{#__RefHeading___Toc43630513 .anchor}ACKNOWLEDGMENTS

This standard was formulated by the Law Enforcement Standards Laboratory
of the National Bureau of Standards under the direction of Ralph A.
Gorden Jr., Manager, Protective Equipment Program, and Lawrence K.
Eliason, Chief of LESL. The technical research was Performed by Nicholas
J. Calvano of the NBS Center for Consumer Product Technology. The
standard has been reviewed and approved by the Technology Assessment
Program Advisory Council and adopted by the [International Association
of Chiefs of Police
(IACP)](http://www.nist.gov/cgi-bin/exit_nist.cgi?url=http://www.amdahl.com/ext/iacp/&timeout=7)
as an IACP Standard.

**For sale by the Superintendent of Documents, U.S. Government Printing
Office, Washington, DC 20402**

[]{#__RefHeading___Toc43630514 .anchor}FOREWORD

This document. NIJ Standard-0106.01, Ballistic Helmets. is an equipment
standard developed by the Law Enforcement Standards Laboratory of the
National Bureau of Standards. It is produced as part of the Technology
Assessment Program of the National Institute of Justice. A brief
description of the program appears on the inside front cover.

This standard is a technical document that specifies performance and
other requirements equipment must meet to conform to the needs of
criminal justice agencies for high quality service. Purchasers can use
the test methods described in this report to determine firsthand whether
a particular piece of equipment meets the standards, or they may have
the tests conducted on their behalf by a qualified testing laboratory.
Procurement officials may also refer to this standard in their
purchasing documents and require that equipment offered for purchase
meet the requirements. with compliance guaranteed by the vendor or
attested to by an independent laboratory.

Because this NIJ standard is designed as a procurement aid. it is
necessarily highly technical. For those who seek general guidance about
the capabilities of ballistic helmets, user guides also are published.
The guides explain in non-technical language how to select equipment
capable of the performance required by an agency.

NIJ standards are subjected to continuing review. Technical comments and
recommended revisions are welcome. Please send suggestions to the
Program Manager for Standards, National Institute of Justice, U.S.
Department of Justice, Washington, DC 20531.

Before citing this or any other NIJ standard in a contract document,
users should verify that the most recent edition of the standard is
used. Write to: Chief, Law Enforcement Standards Laboratory, National
Bureau of Standards. Washington, DC 20234.

Lester D. Shubin\
Program Manager for Standards\
National Institute of Justice

[]{#__RefHeading___Toc43630515 .anchor}TABLE OF CONTENTS

[ACKNOWLEDGMENTS ii](#__RefHeading___Toc43630513)

[FOREWORD ii](#__RefHeading___Toc43630514)

[TABLE OF CONTENTS iii](#__RefHeading___Toc43630515)

[1. PURPOSE AND SCOPE 1](#purpose-and-scope)

[2. CLASSIFICATION 1](#classification)

[2.1 Type I (22 LR-38 Special) 1](#__RefHeading___Toc43630518)

[2.2 Type II-A (Lower Velocity 357 Magnum-9 mm)
1](#__RefHeading___Toc43630519)

[2.3 Type II (Higher Velocity 357 Magnum-9 mm)
1](#__RefHeading___Toc43630520)

[2.4 Special Type 2](#__RefHeading___Toc43630521)

[3. DEFINITIONS 2](#definitions)

[3.1 Angle of Incidence 2](#__RefHeading___Toc43630523)

[3.2 Basic Plane 2](#__RefHeading___Toc43630524)

[3.3 Coronal Plane 2](#__RefHeading___Toc43630525)

[3.4 Fair Hit 2](#__RefHeading___Toc43630526)

[3.5 Full Metal Jacketed Bullet (FMJ) 2](#__RefHeading___Toc43630527)

[3.6 Jacketed Soft Point (JSP) 2](#__RefHeading___Toc43630528)

[3.7 Lead Bullet 2](#__RefHeading___Toc43630529)

[3.8 Mid-sagittal Plane 2](#__RefHeading___Toc43630530)

[3.9 Penetration 2](#__RefHeading___Toc43630531)

[3.10 Reference Plane 3](#__RefHeading___Toc43630532)

[3.11 Witness Plate 3](#__RefHeading___Toc43630533)

[4. REQUIREMENTS 3](#requirements)

[4.1 Sampling for Test 3](#__RefHeading___Toc43630535)

[4.2 Test Sequence 3](#__RefHeading___Toc43630536)

[4.3 Projections 3](#__RefHeading___Toc43630537)

[4.4 Openings 3](#__RefHeading___Toc43630538)

[4.5 Workmanship 4](#__RefHeading___Toc43630539)

[4.6 Labeling 5](#__RefHeading___Toc43630540)

[4.7 Ballistic Penetration 5](#__RefHeading___Toc43630541)

[4.8 Ballistic Impact Attenuation 5](#__RefHeading___Toc43630542)

[5. TEST METHODS 5](#test-methods)

[5.1 Test Equipment 5](#__RefHeading___Toc43630544)

[5.1.1 Type I Test Weapons and Ammunition
5](#type-i-test-weapons-and-ammunition)

[5.1.2 Type II-A Test Weapons and Ammunition
6](#type-ii-a-test-weapons-and-ammunition)

[5.1.3 Type II Test Weapons and Ammunition 5.1.3.1 Higher Velocity 357
Magnum
7](#type-ii-test-weapons-and-ammunition-5.1.3.1-higher-velocity-357-magnum)

[5.1.4 Chronograph 7](#__RefHeading___Toc43630548)

[5.1.5 Penetration Test Headforms 7](#__RefHeading___Toc43630549)

[5.1.6 Impact Test Headform 7](#__RefHeading___Toc43630550)

[5.1.7 Witness Plate 7](#__RefHeading___Toc43630551)

[5.1.8 Acceleration Measurement System 7](#__RefHeading___Toc43630552)

[5.2 Ballistic Penetration Test 11](#__RefHeading___Toc43630553)

[5.3 Ballistic Impact Attenuation Test 11](#__RefHeading___Toc43630554)

[APPENDIX A-REFERENCES 13](#appendix-a-references)

**NIJ STANDARD 0106.01 FOR BALLISTIC HELMETS**

# 1. PURPOSE AND SCOPE

The purpose of this standard is to establish performance requirements
and methods of test for helmets intended to protect the wearer against
gunfire. Requirements for face shields are not included in this
standard. The standard is a revision of NILECJ-STD-0106.00, dated
September 1975.

This revision redefines the classification system, and establishes
threat levels and test rounds that are consistent with companion NIJ
standards for ballistic protective equipment and materials \[l,4\]\*.

# 2. CLASSIFICATION

Ballistic helmets covered by this standard are classified into three
types, by level of performance.

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, helmets that will defeat a standard test
round may not defeat other loadings in the same caliber. For example, a
helmet that prevents penetration by a 357 Magnum test round may or may
not defeat a 357 Magnum round with higher velocity. Similarly, for
identical striking velocities, non-deforming or armor piercing rounds
pose a significantly greater penetration threat than an equivalent lead
core round of the same caliber. The test ammunition specified in this
standard represent common threats to the law enforcement community.

[]{#__RefHeading___Toc43630518 .anchor}***2.1 Type I (22 LR-38 Special)\
***This helmet protects against the standard test rounds as defined in
paragraph 5.1.1. It also provides protection against lesser threats such
as 12 gauge No. 4 lead shot and most handgun rounds in calibers 25 and
32.

[]{#__RefHeading___Toc43630519 .anchor}***2.2 Type II-A (Lower Velocity
357 Magnum-9 mm)\
***This helmet protects against the standard test rounds as defined in
paragraph 5.1.2. It also provides protection against lesser threats such
as 12 gauge 00 buckshot, 45 Auto., 22 caliber Long Rifle High Velocity
(rifle), High Velocity 38 Special and some other factory loads in
caliber 357 Magnum and 9 mm, as well as the threats mentioned in
paragraph 2.1.

[]{#__RefHeading___Toc43630520 .anchor}***2.3 Type II (Higher Velocity
357 Magnum-9 mm)\
***This helmet protects against the standard test rounds as defined in
paragraph 5.1.3. It also provides protection against lesser threats such
as 12 gauge 00 buckshot, 45 Auto., 22 caliber Long Rifle High Velocity
(rifle), High Velocity 38 Special and most other factory loads in
caliber 357 Magnum and 9 mm, as well as the threats mentioned in
paragraph 2.1.

[]{#__RefHeading___Toc43630521 .anchor}***2.4 Special Type\
***A purchaser having a special requirement for a level of protection
other than one of the above standards should specify the exact test
rounds to be used, and indicate that this standard shall govern in all
other respects.

# 3. DEFINITIONS

[]{#__RefHeading___Toc43630523 .anchor}***3.1 Angle of Incidence\
***The angle between the line of flight of a bullet and the
perpendicular to the plane tangent to the point of impact. See figure 1.

[]{#__RefHeading___Toc43630524 .anchor}***3.2 Basic Plane\
***The plane through the centers of the external ear openings and the
lower edges of the eye sockets. See figure 2.

[]{#__RefHeading___Toc43630525 .anchor}***3.3 Coronal Plane\
***The plane, perpendicular to the basic and mid-sagittal planes, which
passes through the centers of the external ear openings. See figure 2.

[]{#__RefHeading___Toc43630526 .anchor}***3.4 Fair Hit\
***A hit that impacts the helmet at an angle of incidence no greater
than 5°, and is at least 5 cm (2 in) from a prior hit or the edge of the
helmet. A bullet that impacts too close to the edge or a prior hit
and/or is of too high a velocity, but does not penetrate, shall be
considered a fair hit for the determination of penetration.

[]{#__RefHeading___Toc43630527 .anchor}***3.5 Full Metal Jacketed Bullet
(FMJ)\
***A bullet made of lead completely covered, except for the base, with
copper alloy (approximately 90 copper-10 zinc).

[]{#__RefHeading___Toc43630528 .anchor}***3.6 Jacketed Soft Point (JSP)\
***A bullet made of lead completely covered, except for the point, with
copper alloy (approximately 90 copper-10 zinc).

[]{#__RefHeading___Toc43630529 .anchor}***3.7 Lead Bullet\
***A bullet made of lead alloyed with hardening agents.

[]{#__RefHeading___Toc43630530 .anchor}***3.8 Mid-sagittal Plane\
***The plane, perpendicular to the basic and coronal planes, which
symmetrically bisects the head. See figure 2.

[]{#__RefHeading___Toc43630531 .anchor}***3.9 Penetration\
***Perforation of a witness plate by any part of the test specimen or
test bullet, as determined by the passage of light when the witness
plate is held up to a 60-W light bulb.

[]{#__RefHeading___Toc43630532 .anchor}***3.10 Reference Plane\
***The plane 60±1 mm (2.36±0.04 in) above and parallel to the basic
plane. See figure 2.

[]{#__RefHeading___Toc43630533 .anchor}***3.11 Witness Plate\
***A thin sheet of aluminum whose perforation serves as a means of
determining penetration.

# 4. REQUIREMENTS

[]{#__RefHeading___Toc43630535 .anchor}***4.1 Sampling for Test\
***Three helmets, size 7 l/4 and selected at random, shall constitute a
test sample.

[]{#__RefHeading___Toc43630536 .anchor}***4.2 Test Sequence\
***The helmets shall be examined to determine compliance with the
requirements of paragraphs 4.3 through 4.6, and shall then be tested for
compliance with the requirements of paragraphs 4.7 and 4.8 in that
sequence.

[]{#__RefHeading___Toc43630537 .anchor}***4.3 Projections\
***The helmets shall have no rigid projections that protrude from the
inside shell surface.

[]{#__RefHeading___Toc43630538 .anchor}***4.4 Openings\
***The helmets shall have no slits, holes, or other openings.

 

[]{#__RefHeading___Toc43630539 .anchor}***4.5 Workmanship\
***The helmets shall be free from dents, blisters, cracks, crazing,
chipped or sharp corners and other evidences of inferior workmanship.

[]{#__RefHeading___Toc43630540 .anchor}***4.6 Labeling\
***Each helmet shall be permanently and legibly labeled so that the
label can be easily read without removing padding or any other permanent
part, and shall include the following information:

a.  name, designation, or logo of the manufacturer

b.  type of helmet, according to section 2 of this standard

c.  size

d.  month and year of manufacture

e.  lot number

[]{#__RefHeading___Toc43630541 .anchor}***4.7 Ballistic Penetration\
***Two helmets shall be tested for resistance to ballistic penetration
in accordance with paragraph 5.2. Penetration by any fair hit shall
constitute failure. The detailed ballistic performance requirements are
summarized in table 1.

[]{#__RefHeading___Toc43630542 .anchor}***4.8 Ballistic Impact
Attenuation\
***One helmet shall be tested for ballistic impact attenuation in
accordance with paragraph 5.3. No measured peak acceleration shall
exceed 400 g~n~ , (400 times the acceleration due to gravity).

# 5. TEST METHODS

[]{#__RefHeading___Toc43630544 .anchor}***5.1 Test Equipment\
***It should be noted that hand-loaded ammunition may be required to
achieve some of the bullet velocities required in the following
paragraphs.

### 5.1.1 Type I Test Weapons and Ammunition 

**5.1.1.1    22 LR\
**The test weapon may be a 22 caliber handgun or test barrel. The use of
a handgun with a 15 to 16.5 cm (6 to 6.5 in) barrel is suggested. Test
bullets shall be 22 Long Rifle High Velocity lead, with nominal masses
of 2.6 g (40 gr) and measured velocities of 320±12 m (1050±40 ft) per
second.

**5.1.1.2 38 Special\
**The test weapon may be a 38 Special handgun or test barrel. The use of
a handgun with a 15 to 16.5 cm (6 to 6.5 in) barrel is suggested. Test
bullets shall be 38 Special round-nose lead, with nominal masses of 10.2
g (158 gr) and measured velocities of 259±15 m (850±50 ft) per second.

  -----------------------------------------------------------------------------------------------------
  **TABLE 1.                                                                           
  *Test                                                                                
  summary* **                                                                          
  ------------- -------------- ----------- ------------- ------------ ---------------- ----------------
                **Test                                                **Performance    
                variables**                                           requirements**   

  **Helmet      **Test         **Nominal   **Suggested   **Required   **Required fair  **Permitted
  type**        ammunition**   bullet      barrel        bullet       hits per helmet  penetrations**
                               mass**      length**      velocity**   part**           

  **I**         22 LRHV Lead   2.6 g\      15 to 16.5    320±12 m/s\  4                0
                               50 gr       cm\           1050±40 ft/s                  
                                           6 to 6.5 in                                 

                38 Special\    10.2 g\     15 to 16.5    259±15 m/s\  4                0
                RN Lead        158 gr      cm\           850±50 ft/s                   
                                           6 to 6.5 in                                 

  **II-A**      357 Magnum\    10.2 g\     10 to 12 cm\  381±15 m/s\  4                0
                JSP            158 gr      4 to 4.75 in  1250±50 ft/s                  

                9 mm\          8.0 g\      10 to 12 cm\  332±15 m/s\  4                0
                FMJ            124 gr      4 to 4.75 in  1090±50 ft/s                  

  **II**        357 Magnum\    10.2 g\     15 to 16.5    425±15 m/s\  4                0
                JSP            158 gr      cm\           1395±50 ft/s                  
                                           6 to 6.5 in                                 

                9 mm\          8.0 g\      10 to 12 cm\  358±15 m/s\  4                0
                FMJ            124 gr      4 to 4.75 in  1175±50 ft/s                  
  -----------------------------------------------------------------------------------------------------

**Abbreviations:**

> FMJ---Full Metal Jacketed\
> JSP---Jacketed Soft Point\
> LRHV---Long Rifle High Velocity
>
> RN---Round Nose

### 5.1.2 Type II-A Test Weapons and Ammunition 

**5.1.2.1 Lower Velocity 357 Magnum\
**The test weapon may be a 357 Magnum handgun or test barrel. The use of
a handgun with a 10 to 12 cm (4 to 4.75 in) barrel is suggested. Test
bullets shall be 357 Magnum jacketed soft point, with nominal masses of
10.2 g (158 gr) and measured velocities of 381±15 m (1250±50 ft) per
second.

**5.1.2.2 Lower Velocity 9 mm\
**The test weapon may be a 9 mm handgun or test barrel. The use of a
handgun with 10 to 12 cm (4 to 4.75 in) barrel is suggested. Test
bullets shall be 9 mm full metal jacketed, with nominal masses of 8.0 g
(124 gr) and measured velocities of 332±15 m (1090±50 ft) per second.

### 5.1.3 Type II Test Weapons and Ammunition **5.1.3.1 Higher Velocity 357 Magnum** 

The test weapon may be a 357 Magnum handgun or test barrel. The use of a
handgun with a 15 to 16.5 cm (6 to 6.5 in) barrel is suggested. Test
bullets shall be 357 M g a num jacketed soft point, with nominal masses
of 10.2 g (158 gr) and measured velocities of 425±15 m (1395±50 ft) per
second.

**5.1.3.2 Higher Velocity 9 mm\
**The-test weapon may be a 9 mm handgun or test barrel. The use of a
handgun with a 10 to 12 cm (4 to 4.75 in) barrel is suggested. Test
bullets shall be 9 mm full metal jacketed, with nominal masses of 8.0 g
(124 gr) and measured velocities of 358±15 m (1175±50 ft) per second.

[]{#__RefHeading___Toc43630548 .anchor}**5.1.4 Chronograph\
**The chronograph shall have a precision of 1 µs and an accuracy of 2
µs. Its triggering devices shall be of either the photoelectric or
conductive screen types.

[]{#__RefHeading___Toc43630549 .anchor}**5.1.5 Penetration Test
Headforms\
**Each penetration test headform shall be size 7 l/4 and shall have the
dimensions shown in figure 3. The sagittal penetration type shall be so
modified that it can rigidly hold a witness plate in the coronal Plane
as shown in figure 4. Conversely, the coronal penetration type shall be
able to hold a witness plate in the sagittal plane. as shown in figure
4.

[]{#__RefHeading___Toc43630550 .anchor}**5.1.6 Impact Test Headform\
**The impact test headform shall be size 7 l/4. shall have the
dimensions given in figure 3, and shall exhibit no resonance frequencies
below 3000 Hz: it may be made of any suitable material. such as
magnesium alloy K-1A. A test headform found to be suitable can be
obtained from United States Testing Laboratories, Inc., 1415 Park
Avenue, Hoboken, NJ 07030.

The impact headform shall be rigidly mounted on a base (see fig. 5)
which is free to move In the direction of motion of the test bullet. The
total mass of the instrumented headform and base assembly shall be
5.0±0.5 kg (11 ± 1.1 lb) and the static force, parallel to the direction
of motion, required to initiate motion of the assembly shall not exceed
9 N (2 lbf).

[]{#__RefHeading___Toc43630551 .anchor}**5.1.7 Witness Plate\
**The witness plates shall be 0.5 mm (0.020 in) thick and shall be made
of type 2024-T3 or 2024-T4 aluminum alloy.

[]{#__RefHeading___Toc43630552 .anchor}**5.1.8 Acceleration Measurement
System\
**The accelerometer should be able to withstand shocks up to 2000 g~n~ .
The acceleration data channel, including all instrumentation which may
alter the frequency content of the test data and all recording and
analysis procedures, shall comply with SAE Recommended Practice J211b
requirements for channel class 1000 \[5\].

 

[]{#__RefHeading___Toc43630553 .anchor}***5.2 Ballistic Penetration
Test\
***Set up the test equipment as shown in figure 6. Firmly clamp the
appropriate test weapon, with the barrel horizontal. in such a manner
that the alignment of the weapon is not altered when it is discharged.
Use the test weapon and ammunition combination in accordance with
paragraphs 5.1.1.1 through 5.1.3.2 as appropriate for the threat level
classification of the helmet as rated by the manufacturer in accordance
with section 2.

Position a sheet of cardboard 5 m (16 ft) from the muzzle of the test
weapon and fire a pre-test round through the cardboard to determine the
line of flight and the point of impact of the bullet.

Place the triggering devices 2 and 3 m (6.6 and 9.8 ft), respectively,
from the muzzle of the test weapon and arrange them so that they define
planes perpendicular to the line of flight of the bullet. Measure the
distance between them with an accuracy of 1 mm (0.04 in).

Insert a witness plate in the sagittal penetration test headform. place
the helmet under test on the headform and secure it by its chin strap or
by other means which will not interfere with the test. Place the
helmeted headform in back of the sheet of cardboard, with the desired
point of impact touching the bullet hole made by the test round. and
then remove the cardboard.

Fire one round at the front of the helmet, hitting it at a point no more
than 9 cm (3.5 in) above the basic plane and no more than 5 cm (2 in)
from the mid-sagittal plane. Record the time of flight of the bullet
between the two triggering screens, as determined by the chronograph,
and calculate the bullet velocity. Then fire a round at the back of the
helmet, impacting it within the area diametrically opposite the front
impact area. Examine the helmet and witness plate to determine whether
penetration occurred when a bullet traveling at an acceptable speed made
a fair hit within the required area.

If no penetration occurred, place the helmet on the coronal penetration
test headform and shoot it once on each side. at a point no more than 5
cm (2 in) above the basic plane and no more than 7.5 cm (3.0 in) from
the coronal plane.

If no penetration occurs, repeat the above test on a second helmet,
which has been preconditioned by immersion for 2 to 4 h in water at
25±5°C (77±9°F).

[]{#__RefHeading___Toc43630554 .anchor}***5.3 Ballistic Impact
Attenuation Test\
***Set up the test equipment as shown in figure 6 and locate the line of
fire and point of impact of the bullet as described in paragraph 5.2.
Use the test weapon and ammunition combination in accordance with
paragraphs 5.1.1.1 through 5.1.3.2 as appropriate for the threat level
classification of the helmet as rated by the manufacturer in accordance
with section 2.

Mount the accelerometer at the center of mass of the impact test
headform in such a manner that it can be easily repositioned for all
impacts: a universal ball-and-socket mount has been found to be
suitable. Position the helmet squarely on the headform and secure it by
its chin strap or other means which will not interfere with the test.
Position the instrumented test headform-base assembly in the line of
fire so that the sensitive axis of the accelerometer and the line of
fire are colinear within 5°.

Allow all electronic equipment to warm up for 30 min or until stability
is achieved, whichever time is greater, prior to testing, and perform
the tests at an ambient temperature of 20-28°C (68-82 °F) and a relative
humidity of 30 to 70%. Shoot four test rounds at the helmet, one at each
of the four sites as described in paragraph 5.2, and measure the
velocity of each fair hit and the headform acceleration which it
produces.

# APPENDIX A-REFERENCES 

1.  NILECJ-STD-0101.01, \"The Ballistic Resistance of Body Armor,\"
    National Institute of Justice, U.S. Department of Justice.
    Washington, DC 20531 (Dec. 1978).

2.  NIJ Standard-0104.01, \"Riot Helmets,\" National Institute of
    Justice, U.S. Department of Justice, Washington, DC 20531 (Aug.
    1980).

3.  NILECJ-STD-0105.00, \"Crash Helmets,\" National Institute of
    Justice, U.S. Department of Justice, Washington, DC 20531 (June
    1975).

4.  NIJ Standard-0108.00, \"Ballistic Resistant Protective Materials.\"
    (In preparation).

5.  SAE Recommended Practice J211b, [Society of Automotive Engineers,
    Inc.,](http://www.nist.gov/cgi-bin/exit_nist.cgi?url=http://www.sae.org)
    Two Pennsylvania Plaza, New York, NY.

\* United States Government Printing Office:1982\--361-233/6344