hk mark23 User Guide

A firearm has the capability of taking your life or the life of someone else! Be extremely careful with your

firearm. An accident can occur at anytime and is almost always the result of not following basic safety rules.

Sterling, Virginia 20166-8903

Telephone (703) 450-1900

United States of America

21480 Pacific Blvd.

WARNING

CONTRACT NUMBER N00164-94-C-0040 SW370-BD-OPI-010

Mark 23 Pistol, Semi-automatic,

Operator’s Manual

Caliber .45 ACP

SECTION IV OPERATION UNDER UNUSUAL CONDITIONS ................................................................................................ 23

2.9 Readying the Pistol for Firing .................................................................................................... 21

2.10 Firing the Pistol ........................................................................................................................ 22

2.11 Extreme Cold............................................................................................................................ 23

2.12 Hot, Wet Climates .................................................................................................................... 23

2.13 Hot, Dry Climates ..................................................................................................................... 24

2.14 Heavy Rain and Water Operations - All Climates ................................................................... 24

SECTION III OPERATION UNDER NORMAL CONDITIONS .................................................................................................. 18

2.6 Clearing Procedures .................................................................................................................. 18

2.7 Loading and Unloading the Magazine ....................................................................................... 19

2.8 Loading Procedure ..................................................................................................................... 20

2.5 Safety Features .......................................................................................................................... 17

SECTION II GENERAL DESCRIPTION .................................................................................................................................... 10

CHAPTER 2 OPERATING INSTRUCTIONS............................................................................................................................. 10

SECTION I SERVICE UPON RECEIPT OF MATERIAL........................................................................................................... 10

2.2 Description.................................................................................................................................. 10

2.3 Operation and Characteristics ................................................................................................... 11

2.4 Cycle of Operation ..................................................................................................................... 13

2.1 Initial Inspection ......................................................................................................................... 10

1.5 Technical Specifications ...............................................................................................................9

SECTION II PISTOL DESCRIPTION............................................................................................................................................6

CHAPTER 1 INTRODUCTION..................................................................................................................................................... 4

SECTION I GENERAL INFORMATION........................................................................................................................................4

1.2 Nomenclature ................................................................................................................................6

1.3 Principle of Operation .................................................................................................................. 7

1.4 Major Assembly Groups ............................................................................................................... 7

TABLE OF CONTENTS

PAGE

FIREARM SERVICE RECORD ................................................................................................................... INSIDE BACK COVER

3.8 Inspection ................................................................................................................................... 37

3.9 Lubrication .................................................................................................................................. 38

3.10 Operator Troubleshooting Procedures .................................................................................... 43

3.11 Parts Listing and Exploded Diagram ....................................................................................... 46

SECTION II PMS CHECKS & MAINTENANCE PROCEDURES.............................................................................................. 27

3.3 Disassembly (Field stripping) ..................................................................................................... 28

3.4 Reassembly (From field strip).................................................................................................... 30

3.5 Safety/Function Check............................................................................................................... 33

3.6 Function Firing............................................................................................................................ 36

3.7 Cleaning ..................................................................................................................................... 36

3.1 Operator Tools and Equipment Required.................................................................................. 27

3.2 General ....................................................................................................................................... 27

SECTION V MALFUNCTIONS AND STOPPAGES .................................................................................................................. 25

CHAPTER 3 MAINTENANCE INSTRUCTIONS ....................................................................................................................... 27

SECTION I TOOLS & EQUIPMENT .......................................................................................................................................... 27

2.15 Remedial Action ........................................................................................................................ 25

SECTION III ADJUSTMENT OF SIGHTS ................................................................................................................................. 40

SECTION IV TROUBLESHOOTING PROCEDURES............................................................................................................... 43

CHAPTER 4 AMMUNITION ....................................................................................................................................................... 48

requirements ever demanded of a combat handgun.

The Mark 23 provides this accuracy without the need for

hand-fitted parts common in custom-built match pistols

costing thousands of dollars more. Repair of the Mark 23

is reduced to a simple parts exchange.

The HK Mark 23, is a commercial model of the U.S.

Government issue MK 23, MOD 0 pistol and is available

in limited numbers. Designated the “Mark 23”, it is almost

identical to the MK 23, MOD 0 pistol used by the Special

Operations Command, right down to its threaded barrel.

The main differences are slide Markings (Mark 23 as

opposed to MK 23) and a barrel manufactured to SAMMI

headspace specifications.

One of the most thoroughly tested handguns in history,

the MK23/Mark 23 project originated in 1991 when HK

was awarded a development contract for the Special

SECTION I - GENERAL INFORMATION

The HK Mark 23 .45 ACP pistol give shooters match

grade accuracy equal to that of the finest custom made

handguns — yet it exceeds the most stringent operational

CHAPTER 1 INTRODUCTION

spread in 5-round shot groups at 25 meters with service

ammunition. Endurance testing demonstrated a service

life of over 30,000 rounds of +P ammunition with no parts

breakage, with an additional 30,000 rounds certified on

the slide and frame.

To meet the reliability requirement, the pistol had to

demonstrate a minimum of 2,000 mean rounds between

stoppages (MRBS) with both M1911 ball and +P

ammunition. The minimum MRBS achieved in testing was

6,027 and the maximum was 15,122!

During over 450 accuracy test firings from a precision

firing fixture, MK 23 pistols far exceeded the government

requirement, averaging 1.44 inches, with 65 groups of

less than one inch. There were four groups of .5 inches,

with 5 rounds going through the same hole! This included

firing with and without the sound/flash suppressor

attached.

Operations Forces Offensive Handgun Weapon System,

consisting of a caliber .45 pistol, detachable sound and

flash suppressor, and laser aiming module (LAM).

During testing, MK 23 pistols met the most stringent

operational and accuracy requirements ever demanded of

a combat handgun. MK 23 pistols achieved match grade

accuracy of less than a 2.5 inch maximum extreme

To meet operational environmental requirements, the

pistol was function tested at +140 and -25

salt water, exposed to surf, salt-fog, sand-dust, mud,

icing, unlubricated, and a variety of other fouled

environments. A special maritime surface coating protects

the pistol from corrosion, in all of these operational

environments.

The barrel is threaded to accept accessories such as a

flash and sound suppressor. The unique HK polygonal

bore profile increases muzzle velocity and service life,

reduces bore fouling and eases cleaning.

The frame mounted MK 23 decocking lever is separate

from the ambidextrous safety lever. It allows the hammer

to be lowered quietly and safely from the single action

position. When the hammer is down, the ambidextrous

frame mounted safety lever is locked in the fire position

so that the pistol is always ready for double action

F, immersed in

Three pistols were tested for accuracy after firing over

30,000 rounds, the specified service life of the pistol, and

still met the new pistol accuracy requirement. An

innovative design feature, a high temperature rubber O-

ring on the barrel that seals the barrel in the slide until

unlocking, led to this remarkable achievement. The O-ring

lasts beyond 20,000 rounds and can be replaced by the

operator without tools in seconds.

enter U.S. military service since the venerable

Government Model 1911A1. On May 1, 1996, the first MK

23 pistols were delivered to the U.S. Special Operations

Command for operational deployment.

a 3-dot sight picture with white or optional self-luminous

tritium dots.

The MK 23 became the first caliber .45 ACP pistol to

frame, a one-piece machined steel slide, and a law

enforcement/military magazine capacity of twelve rounds.

The weapon is aimed using either iron sights or an

optional laser aiming component. The iron sights provide

Other notable features include accessory mounting

grooves on the frame, a mechanical recoil reduction

system that reduces recoil forces to the shooter and

components of the pistol by as much as 30%, a polymer

finger.

operation. When the hammer is “cocked and locked” in

single action mode with the safety lever on “safe”, the

decocker is blocked so that the pistol is always ready for

single action operation. Even with the safety lever

engaged, the slide can still be manipulated to load and

clear the pistol.

The extended slide release lever and the ambidextrous

magazine release are easily operated without adjustment

of the firing grip using the firing hand thumb or index

1.3 Principle of Operation

A. The Mark 23 uses a modified linkless Browning-

style short recoil system to lock and unlock the

breech.

trigger guard

flared

accessory

mounting

groove

for accessory locking

threaded insert

Figure 1 Left View

threaded barrel

slide

SECTION II - PISTOL DESCRIPTION

1.2 Nomenclature

slide release

magazine

release

magazine

decocking

lever

frame

B. Upon firing, the pressure developed by the

propellent gas forces the slide and barrel

assembly to the rear. After approximately 3 mm,

the locking block will stop the rearward

movement of the barrel as the barrel is pivoted

downward due to the engagement of the angled

surfaces of the locking block with those located

lanyard loop

Figure 2 Right View

magazine

release

left safety

lever

trigger

safety lever

right

slide release

axle recess

accessory

mounting

groove

recess for slide

release/stop

hammer

rear sight

extractor

barrel locking

block

ejection

port

front sight

1.4 Major Assembly Groups (See Figure 3)

A. Slide - houses the firing pin, firing pin block and

Do not rely on the slide lock to determine if

and physically ensure the pistol is not loaded.

the magazine is empty. Always check visually

C. The slide locks open after the last round has

been fired and ejected.

WARNING

in the recoil spring guide rod. The locking block

will disengage from the slide and the slide will

continue rearward.

The extractor located in the slide will then

extract the fired cartridge case, the ejector

located in the frame on the left side of the

magazine well will eject the fired case as the

slide continues rearward and cocks the

hammer, and compresses the recoil spring.

The slide moves forward feeding the next

cartridge from the magazine into the chamber

and locking to the barrel breech.

D. Frame - serves as support to all major

slide. The O-ring holds the barrel tight in the

slide until unlocking.

components; controls functioning of pistol. The

slide release locks the slide with barrel and

recoil/buffer spring assembly to the metal

locking insert cast into the synthetic frame. A

lanyard loop is in the bottom of the grip for

attaching a lanyard. The trigger guard is flared

on both sides to preclude accidental actuation

of the magazine release during holstering.

C. Threaded Barrel (with locking block) -

contains cartridge and propellent gases during

firing. The locking block initiates locking and

unlocking of the breech during movement of

B. Captured Recoil/Buffer Spring Assembly

extractor; cocks hammer during recoil.

(with guide rod) - absorbs recoil and returns

the slide and barrel to their forward positions;

reduces impact of slide on receiver during

recoil. The recoil spring is “captured” by a C-clip

on the end of the guide rod.

E. Magazine - holds the cartridges in position for

feeding and chambering.

mounting groove

accessory

flared trigger guard

threaded insert for

accessory locking

Figure 3 Major Assembly Groups

F. Slide Release

magazine

release

decocker

D. Frame

lanyard loop insert

safety

threads

recoil spring

C-clip

guide rod

buffer spring

B. Captured Recoil/Buffer

Spring Assembly

E. Magazine

C. Threaded

Barrel

O-ring

barrel locking block

A. Slide

F. Slide Release - holds slide to rear when

engaged; releases slide when lever is

depressed.

Maximum Effective Range 54.7 yds (50 m)

Maximum Range (M1911 ball) 1,467 yds (1,341 m)

Rifling polygonal bore right hand twist

Magazine staggered, 12 round capacity (10 round civilian)

Safety Features 1. safety lever (manual), 2. double-action mode with 12.1 lb. trigger

pull, 3. firing pin block, 4. disconnector

Width 1.53 in. (38.8 mm)

Muzzle velocity M1911 230 grain ball 886 fps (270 m/s)

+P 185 grain JHP 1142 fps (348 m/s)

Trigger Pull Single-action 4.85 lbs. (2.20 kg)

Height 5.90 in. (150 mm)

Double-action 12.13 lbs. (5.50 kg)

Pistol (w/ empty 12 or 10 rd magazine) 2.66 lbs. (1.21 kg)

Pistol (w/ 12 rds M1911 Ball) 3.22 lbs. (1.46 kg)

Pistol (w/ 10 rds M1911 Ball) 3.13 lbs. (1.42 kg)

Weight Magazine (empty) 12 or 10 rd. capacity .24 lbs. (.110 kg)

Magazine (w/12 rds M1911 Ball) .81 lbs. (.366 kg)

Magazine (w/10 rds M1911 Ball) .72 lbs. (.327 kg)

1.5 Technical Specifications:

Caliber .45 ACP (Automatic Colt Pistol)

System of Operation short recoil, semi-automatic

Locking System Browning system (modified), linkless

Length Barrel 5.87 in. (149 mm)

Sight radius 7.76 in. (197 mm)

Pistol 9.65 in. (245 mm)

5 Clean, dry and lubricate

6 Assemble para. 3.4

7 Safety/ function check para. 3.5

Step Action Reference

1 Remove pistol and items

2 Remove packing material

3 Check for missing items

4 Field strip weapon and

SECTION I - SERVICE UPON RECEIPT OF MATERIAL

2.1 Initial Inspection. Upon initial receipt, the pistol

is to be inspected to ensure it was received in

proper working order.

CHAPTER 2 OPERATING INSTRUCTIONS

inspect for: para. 3.3

Missing parts

Proper assembly

(if necessary) para. 3.7, 3.9

the pistol will fire from either the hammer

down (DA) or cocked position (SA).

from container

(down) position and a round in the chamber,

ger is pulled with the safety lever in the fire

The Mark 23 incorporates single and double

action modes of operation. Anytime the trig-

SECTION II - GENERAL DESCRIPTION

2.2 Description: The Mark 23 is a semiautomatic,

magazine fed, recoil operated, double/single-action

pistol, chambered for the .45 ACP cartridge up to,

and including, the commercial +P cartridges.

WARNING

2.3 Operation and Characteristics

A. Double/Single Action - For double-action

(DA), pulling the trigger will cock the hammer

and immediately release it discharging a

chambered round. To fire the first chambered

round in single-action (SA), the hammer must

Universal Mounting Grooves of the Mark 23.

loading Pistol (USP) will not work on the

Accessories designed for the Universal Self-

Accessories and follow installation and

precautions carefully.

accessories may result in damage to the

Mark 23 mounting grooves and/or the Mark

23. Such damage is not covered under

warranty. Be certain to use only HK Authorized

pistol. Improperly designed or installed

on the front of the Mark 23 frame allow for a

variety of accessories to be used with the

A pair of Universal Mounting Grooves located

NOTE

D. Decocking Lever - The decocking lever allows

the operator to quietly lower the cocked hammer

without concern of an accidental discharge.

When the hammer is cocked, it may be lowered

C. Loaded Chamber Indicator - The Mark 23

The viewing holes are marked with numerals

denoting the number of rounds remaining within.

The floor plate can be easily removed for

disassembly and cleaning of the magazine

components.

pistol does not have a loaded chamber

indicator. The extractor does not act as a

loaded chamber indicator.

CAUTION

B. Magazine - The magazine is produced from

All shots after the first one will be fired single-

action because the slide automatically recocks

the hammer after each shot.

sheet steel and has a total capacity of 12

rounds. The rounds are positioned within the

magazine in a staggered arrangement. Rounds

are visible through the viewing holes located

along the back side of the magazine housing.

be manually cocked before pulling the trigger.

E. Safety Lever - The safety lever is an

The safety lever is depressed downward into

the “fire” position (See Figure 4b). The safety

lever is not spring actuated and therefore must

be moved manually from one position to the

other by the operator.

of the frame. It is actuated by the firing thumb of

the operator. The safety lever blocks the

release of the cocked hammer when it is in the

engaged (up) “safe” position (See Figure 4a).

ambidextrous “thumb” lever located on the rear

always springs back into its disengaged (up)

position due to the spring pressure exerted by

the decocking spring.

safely by moving the decocking lever fully into

the decocking (down) position. The decocking

lever cannot be depressed (and therefore does

not allow the hammer to be lowered) if the

safety lever is engaged. The decocking lever

The safety lever cannot be placed in the “safe” (up)

position if the hammer is uncocked (down).

Figure 4a “Safe” Position Figure 4b “Fire” Position

safety lever engaged when carried in the

single action mode. While there is a spring

The pistol should always be carried with the

detent to prevent this, the safety lever can be

moved to the “fire” position (down) with a

minimum amount of force. This could happen

during careless handling or during removal

of the pistol from the holster. Always check

the position of the safety lever during

handling.

white dot

hammer

WARNING

red dot

hammer

left safety

lever

left safety

G. Slide Release Lever - This lever is used to lock

A threaded insert is molded into the front face of

the trigger guard and the frame is grooved

forward of the trigger guard for attachment of an

accessory such as a laser aiming device or an

illuminator. The frame is a one-piece molded

component with metal inserts (locking insert and

guiding part) cast into the frame during

production. The slide rides on these metal

inserts during operation.

the slide open and for disassembling the

weapon. As a slide stop, it is depressed upward

by the magazine follower or the operator’s

finger as the slide travels rearward during recoil

2.4 Cycle of Operation. Begins with weapon

loaded, hammer cocked, safety lever disengaged.

Depressing this lever with the firing hand index

finger or thumb will allow the magazine to drop

from the grip. The magazine release lever is

shielded from accidental actuation by the flared

trigger guard and the design of the synthetic

frame surrounding the lever.

H. Magazine Release Lever - This ambidextrous,

spring actuated lever holds the magazine within

the grip by engaging in the notch found in the

upper third of the magazine housing.

F. Frame - The front and back straps of the

fiberglass reinforced polymer frame are

checkered to ensure a firm grip, even with wet

hands or under conditions of rapid fire. The

trigger guard is extended, recurved and grooved

to provide a firm grip when using two hands or

gloves. The bottom of the trigger guard is flared

on both sides in front of the magazine release

lever to shield the lever from accidental

actuation.

or manual operation. The slide release lever

engages the recess visible on the left side of the

slide and is spring actuated. The slide release

spring holds the slide release lever in a

disengaged (down) position until required. As a

disassembly lever, the slide release lever is

removed from the left side of the frame when

the slide is held rearward (see para. 3.3). The

slide release lever can be actuated by the firing

thumb of the right handed operator or the index

finger of the left handed operator.

A. Firing - (See Figure 5) Pulling the trigger

rearward pulls the trigger bar forward. The

trigger bar pivots the sear actuator upwards

which disengages the firing pin block. At the

same moment, the sear is pivoted out of

engagement from the lower of the two shelves

located on the hammer. The compressed

hammer spring drives the hammer forward into

block and recoil spring guide rod cause the rear

of the barrel to tilt downward as the slide moves

rearward. By the time the slide and barrel have

recoiled approximately 5 mm, the projectile has

left the barrel and the gas pressure within the

chamber has dropped to a safe level. The barrel

locking block then disengages from the slide.

The slide is now free to recoil rearward

independently of the barrel.

opposing angled

locking surfaces

barrel locking block (locked)

Figure 5 Firing

firing pin

hammer

ﬁ

B. Unlocking - (See Figure 6) The gas pressure

the rear end of the firing pin. The firing pin

strikes the primer of the chambered round. The

propellent is ignited by the primer and propellent

gases are created inside the cartridge case.

The propellent gases drive the projectile down

the polygonal bore which spins the projectile in

a clockwise direction as a means to stabilize the

projectile’s flight.

and energy produced by the propellent gases

push rearward on the slide, which is locked to

the barrel by the engagement of the barrel

locking block within the ejection port milled into

the slide. The opposing angled locking surfaces

incorporated into the design of the barrel locking

D. Ejection - (See Figure 7) -The rim of the

cartridge case strikes the stationary ejector. The

empty case is ejected from the open ejection

port.

C. Extraction -The empty cartridge case is held

firmly against the face of the slide by the claw of

the extractor as the slide recoils rearward.

Figure 6 Unlocking

E. Cocking - (See Figure 7) - As the slide

continues rearward the recoil impulse is

dampened by the buffer spring. The recoil

spring is compressed and the hammer

recocked.

Figure 7 Ejection

recoil spring

guide rod

opposing angled

locking surfaces

recoil spring

slide

barrel locking block

(unlocked)

ejection port

ﬁ

ejection port

hammer

cartridge

case

ejector

slide

ﬁ

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