The FBI's 10mm Pistol
by John C. Hall
NOTICE: TO ALL CONCERNED Certain text files and messages contained on this site deal with activities and devices which would be in violation of various Federal, State, and local laws if actually carried out or constructed. The webmasters of this site do not advocate the breaking of any law. Our text files and message bases are for informational purposes only. We recommend that you contact your local law enforcement officials before undertaking any project based upon any information obtained from this or any other web site. We do not guarantee that any of the information contained on this system is correct, workable, or factual. We are not responsible for, nor do we assume any liability for, damages resulting from the use of any information on this site.
THE FBI'S 10MM PISTOL
By JOHN C. HALL
Special Agent/Unit Chief
Firearms Training Unit
For several decades, FBI Agents carried the .38 caliber revolver
as a standard firearm. Now, after extensive testing and
evaluation, the FBI is converting to a new semiautomatic pistol.
The new pistol, built to FBI specifications and chambered for a
new cartridge; the 10mm, will be issued to all FBI Agents to
replace existing revolvers. This article describes the process
that led to this decision.
The authority for FBI Agents to carry firearms was first granted
in 1934. Although pistols were sometimes issued or permitted on
a limited basis, the revolver predominated as the FBI sidearm.
The first significant shift occurred in 1981, when Special
Weapons and Tactics (SWAT) teams were equipped with large
capacity 9mm pistols. Since then, 9mm pistols have also become
the issue weapons for the FBI's Hostage Rescue Team (HRT) and
special surveillance teams.
For the general Agent population, however, revolvers remained
the issue weapon, though the increasing use of pistols reflected
a growing recognition that the modern pistol provides certain
advantages over the revolver. Primarily, pistols are generally
more compact and portable and provide a larger ammunition
capacity. They are also quicker and easier to reload.
Moreover, experience has shown that pistols are generally easier
to shoot quickly and accurately due to the self©cocking operation
of the slide
following each shot and the more efficient
transmission of recoil. What is most important, however, is that
pistols have proven to be durable and reliable.
Undoubtedly, interest in pistols intensified when innovative
designs of the weapon began to appear on the market during the
early 1980s. Whereas the basic revolver design remains much as
it was at the turn of the century, the pistol has been virtually
refashioned in recent years, providing a wide range of such
innovative features as double©stacked large capacity magazines,
double©action triggers, ambidextrous controls, multiple safety
devices, and endless varieties of shapes and sizes.
Meanwhile, other events entered into the picture. Instances
where law enforcement officers were confronting more violent,
heavily armed subjects appeared to be on the rise. Theincreasing
use of semiautomatic and even fully automatic weapons
by certain segments of the criminal element began to raise
concerns about the adequacy of law enforcement armament.
SELECTION OF A NEW HANDGUN
In 1987, new impetus was given to the FBI's ongoing evaluation of
firearms and ammunition. The Firearms Training Unit, located at
the FBI Academy in Quantico, VA, set out to identify the best
possible handgun for FBI Agents. Firearms training experts
undertook a major testing project to evaluate a variety of 9mm
and .45 caliber pistols then on the market. While several of the
pistols tested were effective, none possessed all of the features
desired in a general issue FBI weapon. The challenge was to
elop a pistol that met the needs of the FBI. In the
meantime, as a response to a growing perception within Agent
ranks that a pistol was preferable to the revolver, the Director
of the FBI authorized Agents to use personally owned pistols,
either 9mm or .45 caliber, as long as the weapons were of
approved manufacture and design and the training and
qualification standards were met.
A Question of Caliber
The most critical, and controversial, issue relating to the
selection of a new FBI handgun was that of caliber. Questions
have been raised not only about the adequacy of some weapons but
also about the wounding effectiveness of some ammunition. Case
accounts of shootings document the fact that subjects receiving
fatal, but not incapacitating, wounds have been able to return
fire and inflict further damage.
As a means of resolving the problem, the FBI convened a Wound
Ballistics Seminar at the FBI Academy in September 1987. The
participants included noted individuals from the scientific and
medical communities from throughout the Nation who possessed
relevant expertise in the field of wound ballistics. One of the
primary purposes of the seminar was to identify the performance
criteria of a bullet most likely to inflict an incapacitating
wound on a human target.
A second purpose of the seminar was to determine, if possible,
which of the two calibers, the 9mm or the .45, was likely to be
most effective in accomplishing that goal. And, although the
seminar was unsuccessful in conclusively resolving the caliber
question, it did identify the desirable performance criteria of
an effective bullet.
Incapacitation, in the law enforcement context, may be simply
described as bringing about the immediate cessation of hostile or
threatening activities. Incapacitation may result from
psychological or physiological factors. Psychologically, some
individuals are predisposed to fall down at the sound of gunfire,
while others may continue to fight even though they are
seriously-©even fatally-©wounded. Because a particular person's
psychological response to a gunshot wound cannot be predicted,
ammunition performance must be viewed from the perspective of
The seminar participants unanimously concluded that
physiological incapacitation can be accomplished in one of two
ways©©damage to the central nervous system (the brain or upper
spinal column) or significant loss of blood. Because the
placement of a shot in the relatively small, highly mobile target
area of the brain cannot be counted upon in an armed
confrontation, a bullet must therefore be capable of penetrating
the body sufficiently to pass through major arteries and blood-
bearing organs to ensure timely physiological incapacitation.
Without adequate penetration, physiological incapacitation cannot
be attained. Given adequate penetration, the only reliable way
to increase the effectiveness of the wound is to increase its
size, thus increasing the amount of tissue damage and the rate of
hemorrhage. Thus, the FBI's test program was designed to
evaluate bullet penetration and wound size.
Ammunition Test Design
With the performance criteria acquired from the Wound Ballistics
Seminar, the next step was to design and construct a series of
ammunition tests to measure the performance of different rounds
against those standards. For that purpose, the Firearms Training
Unit established a working group which included personnel from
the Special Operations and Research Unit, the Hostage Rescue
Team, and the Institutional Research and Development Unit.
The tests were designed to simulate factors realistically.
Therefore, if the effects of bullets upon human tissue were to be
realistically measured, a substance that would duplicate human
tissue was needed. Based upon the research of Dr. Martin
Fackler, Director of the Army's Wound Ballistics Laboratory, at
the Letterman Institute in San Francisco, 10% ballistic gelatin
was selected to simulate soft human muscle tissue. Eight
separate penetration tests were conducted by firing bullets into
Also, since experience demonstrated that bare tissue is seldom
visible on a target in a violent confrontation, seven of the
eight tests included covering the gelatin with typical clothing
material (cotton T©shirt material, flannel shirt material, 10
oz. down in a nylon carrier, and denim). To assure validity and
standardization, clothing manufacturers were consulted to
determine the average thread count in typical underclothing,
shirts, and jackets.
Other factors were then considered. Because FBI Agents
frequently confront subjects in vehicles, behind doors or walls,
and at various distances, clothed gelatin was placed behind
windshield glass, car door metal, plaster board and plywood.
Again, manufacturers in the construction and automobile
industries were consulted to assure that the materials used
replicated substances that bullets would have to pass through in
real©life situations. While most of the test shots were fired
from a distance of 10 feet, some of the tests were conducted at
20 yards to assess the effects of distance and velocity loss on
Five shots were fired in each of the 8 penetration tests,
providing a total of 40 shots for each caliber or bullet type
The Competing Calibers
Once the tests were designed, a decision had to be made
regarding the calibers to be tested. In pistol cartridges, the
two most obvious contenders were the 9mm and .45. The 9mm round
tested was the 147 grain subsonic hollow point round produced by
Winchester; the .45 round selected for the test was the Remington
185 grain hollow point. The selection of these particular
cartridges for testing was based, in large part, on the consensus
of the Wound Ballistic Workshop participants that these bullets
rovide superior penetration over other hollow point
bullets in their respective calibers.
In the meantime, a separate research and development project had
been undertaken with the 10mm cartridge to assess its
application to law enforcement work. Although the 10mm (.40
caliber) is a relatively new cartridge, with few weapons
presently chambered for it, its unique position halfway in size
between the 9mm (.35 caliber) and the .45 appeared to offer the
possibility of a third viable law enforcement pistol cartridge.
In addition, unlike its other competitors, the potential of the
new cartridge was
Samples of commercially available 10mm ammunition were acquired
and preliminarily evaluated as to suitability for law
enforcement use. The high chamber pressures generated by the
commercial loadings, with the resultant heavy recoil and muzzle
blast, tended to offset the otherwise excellent performance of
the round. Therefore, the FBI Firearms Training Unit decided to
create a new loading for the 10mm, one with velocities comparable
to those of the competing 9mm and .45 cartridges. A 180 grain
nt bullet was acquired and handloaded to a velocity of
950 feet per second. This loading not only matched the
velocities of the other two cartridges, but it also dramatically
reduced recoil and muzzle blast.
In the absence of factory ammunition built to the desired
specifications, the 10mm rounds initially subjected to the test
protocol were those handloaded by the Firearms Training Unit
staff. Subsequently, factory©loaded 10mm ammunition was acquired
and built to the desired specifications, which actually met or
surpassed the performance of the handloaded test ammunition.
The Test Procedures
Because the objective was to test ammunition and not weapons, the
initial tests were conducted with industry standard test barrels.
These barrels are built to standards established by the Sporting
Arms and Ammunition Manufacturing Institute (SAAMI) and are
tailored to optimize the ballistic efficiency of each caliber.
Test barrel length is determined by the internal ballistics of
the caliber. Consequently, the barrel lengths vary with each
caliber. For example, the optimal test barrel for the 9mm is 4"
n length, while those of the 10mm and .45 are 6".
The immediate concern was the possibility that the longer test
barrels for the 10mm and .45 would provide an advantage by
increasing their velocities. In reality, it was discovered that
increased velocity actually diminishes the penetration
performance of hollow point bullets in gelatin by increasing the
rate and degree of expansion. It was noted, for example, that
both the 10mm and .45 achieved lower velocities, but greater
penetration, when fired from shorter pistol barrels than when
fired from the long
er test barrels with somewhat higher
velocities. Thus, the longer test barrels used with the 10mm and
.45 worked as a handicap for those two calibers by lessening the
degree of penetration. That handicap would have been eliminated
by using test barrels of equal lengths, and the disparity between
the penetration performance of the 9mm and the two other calibers
would have been even greater than that actually attained. Since
the longer test barrels were not giving any advantage to the 10mm
and the .45 calib
er (quite the contrary), the tests were
continued with existing equipment.
After initial tests to measure velocity and accuracy, 40 rounds
of each caliber were fired by FBI firearms personnel to measure
penetration and wound volume. Following each shot, red dye was
injected into the wound channel created by the passage of the
bullet into the gelatin, and a photograph was taken. Then a
separate team from the Institutional Research and Development
Unit conducted the measurements to ascertain penetration
(measured in inches), bullet expansion, and retained bullet
the volume of tissue displaced (wound size) by
the passage of the bullet was computed in cubic inches and
Although penetration and wound size govern handgun wounding
effectiveness, penetration is the more critical element.
Therefore, a minimum standard of 12" of penetration in the
gelatin was established. The following penetration results
indicate the number and percentage of rounds in each caliber that
met or exceeded the 12" minimum:
10mm - 39 shots out of 40 (97.5%)
.45 - 37 shots out of 40 (92.5%)
9mm - 27 shots out of 40 (67.5%)
As a point of reference, the standard issue .38 Special, 158
grain lead hollowpoint round was fired through the battery of
tests. Although the .38 was not a "test" round, and therefore
not fired under the same strict test controls, the penetration
performance was similar to that of the 9mm, producing acceptable
penetration 67.5% of the time.
It should be noted that no maximum penetration standard was
established. This reflects the judgment that underpenetration of
a handgun bullet presents a far greater risk to the law
enforcement officer than overpenetration does to an innocent
bystander. Considering that approximately 80% of the rounds
fired by law enforcement officers engaged in violent encounters
do not strike the intended targets, it was deemed somewhat
unrealistic to attach too much significance to the potential
risks of overpenetration
on the part of those that do.
Nevertheless, in assessing the potential volume of wounds created
by the test bullets, greater attention was given to the
potential tissue displaced up to a depth of 18". For practical
purposes, penetration beyond that range would most likely carry
the bullet outside the body.
Averaging the volumetric results over all eight test events, the
10mm and .45 displaced similar volumes of tissue within the
desirable penetration range of 18"-4.11 and 4.22 cubic inches
respectively-©well beyond that displaced by the 9mm and .38-ªwhich
respectively measured 2.82 and 2.16 cubic inches.
As an additional consideration, the 10mm was by far the most
accurate round tested, consistently providing one hole 10©shot
groups at 25 yards of less than an inch (0.77" average) with
both handloaded and factory ammunition built to FBI
specifications. By contrast, the 9mm averaged 2.3" and the .45
The conclusion was obvious. The best performing round within the
parameters of the FBI's test protocol was the 10mm.
Accordingly, the Director of the FBI approved the recommendation
that the new 10mm cartridge be adopted as the standard caliber
for a new FBI pistol, and that the new pistol be procured in
sufficient quantities to replace existing revolvers.
The tests that led to this decision by the FBI are available, on
request, to interested law enforcement agencies. Moreover,
ammunition testing will continue, and extend to other calibers
and bullets available for law enforcement use. As additional
test results are compiled, quarterly updates will be automatically
mailed to recipients of the original test report.
Requests for the test report entitled "Ammunition Test Results"
should be mailed to :
Firearms Training Unit
Quantico, VA 22135
FBI Bullet Performance Criteria
a. Minimum Acceptable-12
b. Maximum Desirable-18
2. SIZE OF THE WOUND (Volume)
a. Frontal Area of Bullet
b. Depth of Penetration
FBI Standardized Ammunition Tests
Test 1 - Bare Gelatin @ 10 feet
Test 2 - Heavy Clothing @ 10 feet
Test 3 - 20 gauge Steel @ 10 feet
Test 4 - Wallboard @ 10 feet
Test 5 - Plywood @ 10 feet
Test 6 - Auto Windshield Glass @ 10 feet
Test 7 - Light Clothing @ 20 yards
Test 8 - Auto Glass @ 20 yards