Heckler And Koch HK Mark23 Operators Manual

							11 CAUTION
A pair of Universal Mounting Grooves located
on the front of the Mark 23 frame allow for a
variety of accessories to be used with the
pistol. Improperly designed or installed
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
Accessories and follow installation and
precautions carefully.
NOTE
Accessories designed for the Universal Self-
loading Pistol (USP) will not work on the
Universal Mounting Grooves of the Mark 23.
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 mustbe manually cocked before pulling the trigger.
All shots after the first one will be fired single-
action because the slide automatically recocks
the hammer after each shot.
B. Magazine - The magazine is produced from
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.
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.
C. Loaded Chamber Indicator - The Mark 23
pistol does not have a loaded chamber
indicator. The extractor does not act as a
loaded chamber indicator.
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 
						

							12 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
always springs back into its disengaged (up)
position due to the spring pressure exerted by
the decocking spring.
E. Safety Lever - The safety lever is an
ambidextrous “thumb” lever located on the rear
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).
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.
       
Figure 4a  “Safe” Position      Figure 4b  “Fire” Position
The safety lever cannot be placed in the “safe” (up)
position if the hammer is uncocked  (down).
WARNING
The pistol should always be carried with the
safety lever engaged when carried in the
single action mode. While there is a spring
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.
left safety
 lever
hammer
white dot
left safety
 lever
red dothammer 
						

							13 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.
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.
G. Slide Release Lever - This lever is used to lock
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 recoilor 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.
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.
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.
2.4  Cycle of Operation. Begins with weapon
loaded, hammer cocked, safety lever disengaged. 
						

							14
Figure 5  Firing
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 intothe 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.
B. Unlocking - (See Figure 6) The gas pressure
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
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.
barrel locking block (locked)hammer
opposing angled
locking surfacesfiring pin
fi
fi 
						

							15
Figure 7  Ejection
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 6  Unlocking
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.
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.
barrel locking block
(unlocked)
recoil spring
guide rod
opposing angled
locking surfacesejection port
fi
fi
slide
cartridge
case
recoil springejection port
slide
hammer ejector
fi fi
fi 
						

							16
Figure 8  Feeding
H. Locking - (See Figure 5) -The slide presses the
barrel forward.  As it does, the opposing angled
surfaces of the barrel locking block and recoil
spring guide rod pivot the rear end of the barrel
up into engagement with the ejection port in the
slide.  The slide is now fully forward and the
new round is ready to be fired. F. Feeding - (See Figure 8) -The compressed
recoil spring drives the slide forward.  If the
magazine is empty, the magazine follower will
lift the slide release to a point where it will stop
the forward progress of the slide.  If the
magazine is not empty, the face of the slide will
make contact with the top round in the
magazine. The round will be driven from the
magazine towards the chamber.  The tip of the
projectile is guided into the chamber by the
magazine lips until the round clears the
magazine completely.  At that moment the claw
of the extractor snaps onto the rim of the
cartridge case as it becomes parallel with the
bore.
G. Chambering - The slide pushes the cartridge
forward until the projectile enters the mouth of
the forcing cone of the bore and the face of the
slide contacts the rear of the barrel locking
block.barrel locking block
slide face
slide
recoil springchamber
fi
fifi 
						

							17 2.5  Safety Features
A. Safety Lever - This safety blocks the release of the
cocked hammer in the SA mode. The safety lever
is an external, manually operated, ambidextrous
“thumb” lever located on the left and the right side
of the frame further most back from the trigger. The
safety lever must be manually actuated by the
operator. The shaft of the safety lever moves the
sear block into a position where it blocks the
movement of the sear actuator. The sear actuator,
in turn, does not allow the sear to pivot forward and
thus the hammer cannot be released. Engaging the
safety lever also interrupts the function of the
decocking lever and blocks the hammer
mechanically. The safety lever does not restrict the
movement of the slide. The safety lever is held in
either the fire or safe position by a spring detent.
The safety lever cannot be placed in the safe (up)
position when the hammer is down (uncocked).B. Double-Action Mode - This safety keeps the
hammer in an uncocked condition until the
moment of firing.  The double-action mode
operates as a passive safety feature in the
pistol much as this mode of operation would inany DA revolver or pistol.  The hammer is left
uncocked until the decision to fire is made. At all
times the firing pin is locked by the firing pin
block until the trigger is pulled.  Approximately
12.1 pounds of pressure on the trigger is
required to cock and release the hammer in the
DA mode of operation.  The mode of operation
also permits subsequent hammer strikes on the
same chambered round by simply resqueezing
the trigger.
C. Firing Pin Block - This safety prevents the
firing pin from striking the primer when the
weapon is dropped, the hammer is bumped, or
when the slide slams forward.  The firing pin
block is located in the slide and blocks the
forward movement of the firing pin.  Only when
the trigger is depressed can the sear actuator
push the firing pin block upward against the
downward pressure exerted by the firing pin
block spring. Once the round has been fired and
the slide begins to recoil, the firing pin block is
pushed back down by the firing pin block spring
and engages within the recess provided in the
center portion of the firing pin. 
						

							18 D. Disconnector - This safety prevents the release
of the hammer unless the slide is fully forward
and/or the trigger is reset (released) between
rounds. This important safety prevents serious
malfunctions from occurring, such as “slam-
fires” (rounds that fire during loading), automatic
fire, or a round being fired out of the battery
(with the breech unlocked). The disconnector
disconnects the engagement of the trigger bar
and the sear actuator. The disconnector is
engaged (operating) after the slide has moved
2mm to the rear. The slide presses the leading
edge of the disconnector down and into
engagement with the trigger bar.  When the
slide is fully forward, the leading edge of the
disengaged disconnector resides in a recess
provided in the bottom of the slide.SECTION III - OPERATION UNDER NORMAL CONDITIONS
WARNING
Always clear the pistol before handling it.
2.6  Clearing Procedures
A. The Mark 23 pistol is not considered “clear” or
safe unless:
1. The magazine is removed,
2. The slide is locked to the rear, and
3. The chamber is free of brass or ammunition.
4. The safety lever is set on “safe”.
NEVER ASSUME THE PISTOL IS CLEAR!
B. To Clear the Pistol:
1. Make sure fingers are outside of the trigger
guard and the pistol is pointed  in a safe
direction at all times!
2. Decock Hammer or Engage Safety - depress
decocking lever or engage the safety lever.
3. Remove Magazine - depress the magazine
release lever and remove the magazine from
the frame. 
						

							19 4. Open Slide - lock slide open by pulling slide
rearward as you engage the slide release lever
(up). Watch for live round or empty case to be
ejected.
5. Inspect Chamber - inspect chamber for the
presence of a live round or empty case:
a. Visually view chamber through ejection
port.
b. Physically insert finger into chamber
through ejection port and check for
presence of cartridge case in chamber.
c. Remove any live rounds or empty cases
from the chamber or from within the
weapon.
The pistol is now considered “clear”.2.7  Loading and Unloading the Magazine - (See
Figure 9)
The magazine of the Mark 23 pistol holds 10 rounds
of .45 caliber ammunition in the commercial
magazine and 12 rounds in the Law Enforcement/
Government magazine.
A. Loading the Magazine -
1. Hold the magazine in one hand.2. Hold a round between the index finger and
thumb of the other hand with the projectile
pointing towards the palm.
3. Press the rim of the round down against the
front edge of the follower or the top round in
the magazine and slide the round back under
the magazine lips.
4. Repeat steps 1 - 3 until the magazine is full.
The viewing holes in the back of the magazine
allow the operator to confirm the number of
rounds present within the magazine.
WARNING
Forcefully inserting a loaded magazine into
the Mark 23 may cause the pistol’s slide to
close, chambering a cartridge and making
the Mark 23 ready to fire.
When inserting a magazine, always be
certain that the pistol is pointed in a safe
direction with your fingers off the trigger
and outside the trigger guard. Failure to
do so could cause you to unintentionally
fire the pistol, resulting in serious injury
or death. 
						

							20
Figure 9   Loading the Magazine
B. Unloading the Magazine - exert pressure with
the finger on the base of the cartridge case and
push each  round forward out of the magazine
one round at a time until the magazine is empty.
2.8  Loading Procedure
A. Administrative Loading - used to initially load
the pistol before it is to be fired.
Method A (Slide rearward, chamber empty)1. Make sure fingers are outside of trigger
guard and pistol is pointed in a  safe
direction at all times!
2. Insert magazine firmly into the frame.  Tug on
magazine to insure that it is fully  seated and
engaged.
3. Depress the slide release lever to release the
slide and to chamber the first round.
4. Engage safety lever or depress decocking
lever.
5. Remove magazine and top off with one
additional round.
6. Reinsert magazine insuring that it is fully
seated.
Method B (Slide forward, chamber empty)
1. Make sure fingers are outside of trigger
guard and pistol is pointed in a  safe
direction at all times!
2. Insert magazine firmly into the frame. Tug on
magazine to insure that it is fully  seated and
engaged.
3. Retract the slide fully and release. Do not ride
slide forward!