Heckler And Koch HK Mark23 Operators Manual

							31
Figure 11B  10-Round Civilian Magazine
(Disassembled)
10-Round Civilian Magazine (see Figure 11B)
1. Place the magazine follower onto the
magazine spring with the end of the spring
positioned on the left of the follower.
2. Insert the follower and magazine spring into
the magazine housing.
3. Place the locking insert (on 10-round
magazines) onto the protruding end of the
magazine spring so that the rounded 
corners
face towards the front of the magazine.
4. Push the locking plate down into the magazine
housing against the pressure of the magazine
spring and hold it there.
5. Push the floor plate up onto the base of the
magazine housing until the locking tabs
engage in the sides of the housing. Check to
see if the locking tabs on the floor plate are
securely locked into the housing and the
locking detente on the locking plate fits within
the hole in the floor plate.
6. Check the magazine for proper assembly by
insuring that the follower slides up and down
freely within the magazine housing and with
spring tension. Also check that the magazine
follower rises within the magazine housing to
be nearly flush against the bottom of the
magazine lips.
B. Pistol
1. Insert the muzzle of the barrel through the
large hole located in the front of the slide.
2. Drop the barrel down into the slide and push it
forward until the O-ring engages the slide, the
locking block fits within the ejection port, and
the angled locking surface of the locking block
are visible along the bottom of the slide. The
magazine housing
floor plate magazine
follower
locking insert magazine spring 
						

							32 O-ring will now hold the muzzle tight in the
front of the slide.
3. Install the captured recoil/buffer spring
assembly into the slide so that the front of the
recoil spring guide rod engages in the smaller
hole located in the front of the slide.
4. Align the opposing angled locking surfaces of
the recoil spring guide rod with  those located
on the bottom of the barrel locking block.
5. Push the rear of the recoil/buffer spring
assembly forward enough so that the  recoil
spring retainer can be engaged on the shelf
provided on the front of the  barrel locking
block (see Figure 12).
6. Hold the slide in the right hand with the thumb
holding the rear end of the recoil/buffer spring
assembly in place on the slide (see Figure 13).
7. Hold the frame in the left hand.  Position the
rear of the slide above the front edge of the
frame.
8. Draw the slide back onto the frame so that the
rails of the locking insert and  guiding part slide
within the grooves in the slide.
9. Retract the slide to the point where the recess
in the left side of the slide is centered on the
hole where the axle of the slide release will go.10. Hold the slide in this position and insert the
slide release from the left to right into the
frame until it is flush with the side of the frame
and locks in place.
Figure 12   Proper Position for the Captured Recoil/
Buffer Spring Assembly on the Barrel Locking Blocklocking block
barrel
threads O-ring
shelf
buffer spring recoil spring
guide rod
recoil spring
 C-clip recoil spring
retainer 
						

							33
 Figure 13   Correct Position for Holding Slide
for Reassembly
NOTE
Operator reassembly of the Mark 23 pistol is
now complete, but not finished without a
safety/function check.
3.5  Safety/Function Check
A. A safety/function check should be performed
anytime the pistol is reassembled. This quickcheck indicates whether or not the pistol was
properly assembled and with all the compo-
nents. A properly executed safety/function
check can also reveal many of the more obvious
malfunctions that could occur between the
interactive components of the pistol.
B.
 Always
 clear the pistol before performing a
safety/function check!  
Don’t assume the
pistol is clear!
1. Clear the pistol!
2. Actuate the slide and the operating controls to
insure that:
a. Magazine and catch - the magazine is
held securely in place by the magazine
catch and that it drops free of the frame
when the catch is depressed.
b. Slide - the slide moves freely and without
binding on the frame (with and without a
magazine installed).
c. Barrel - the barrel locking block does lock
fully into battery within the ejection port of
the slide as the slide is closed.
d. Slide Release -
1) The slide release does hold the slide
open when retracted while:
frameslide
thumb holding recoil/buffer spring
assembly on the locking block 
						

							34 a) an empty magazine is in place.
b) the slide release is engaged (pressed
upwards).
2) The slide release does permit the slide to
snap forward when:
a) the slide release is depressed.
b) the slide is retracted without a
magazine installed.
3) The slide release does rebound with
spring pressure.
3. Perform the following safety checks:
a. Safety Lever Test.
1) With the pistol unloaded and hammer
down (uncocked) attempt to press the
safety lever upward into the safe position.
The safety lever should not engage. If the
safety lever engages, return the pistol to
the HK Service Department for service.
2) With the pistol unloaded, the hammer
cocked, move the safety lever several
times from the “safe” to “fire” position. If
the safety lever does not have a pro-nounced stop when moved from “safe” to
“fire” position and back, return the pistol
to the HK Service Department for service.
3) With the pistol unloaded, cock the
hammer and press the safety lever
upward into the safe position. Grasp the
pistol in the shooting position and
squeeze the trigger three or four times.  If
the hammer falls, return the pistol to the
HK Service Department for service.
b. Decocking Lever Test.
1) With the pistol unloaded, cock the hammer
and depress the decocking lever. If the
hammer does not fall or the decocking lever
does not rebound (upward into its normal
position) with spring pressure, return the
pistol to the HK Service Department for
service.
2) With the pistol unloaded, cock the
hammer and press the safety lever
upward into the safe position.  Attempt to
depress the decocking lever three or four 
						

							35 times. If the hammer falls, return the
pistol to the HK Service Department for
service.
c. Decocked (hammer down) Test.
NOTE
On the Mark  23 pistol when decocked (hammer
down), the sear is engaged with the hammer at
a rebounded stop position not touching the
rear of the firing pin.
1) 
With the pistol unloaded, squeeze the
trigger allowing the hammer to cycle in the
double action mode. After the hammer
drops, retain pressure on the trigger. With
the non-firing hand apply pressure with your
finger tips on the rear of the hammer. The
hammer should move forward toward the
firing pin. Release pressure on the trigger
while still retaining pressure with fingers on
hammer. Release pressure on hammer. If
the hammer fails to spring back into the stop
position, return the pistol to the HK Service
Department for service.
2) With the pistol unloaded, hammer
uncocked, trigger forward, apply pressure
to the hammer with your finger tips. If the
hammer moves forward to the firing pin,
return the pistol to the HK Service
Department for service.
d. Disconnector and Trigger Test.
1) With the pistol unloaded, cock the
hammer, push the slide rearward
approximately 3/16 inches (2mm) and
hold in that position while squeezing the
trigger. If the hammer falls, return the
pistol to the HK Service Department for
service.
2) With the pistol unloaded, pull the slide
rearward until the slide stop will engage.
Squeeze the trigger and release the slide
forward simultaneously. If the hammer
falls, return the pistol to the HK Service
Department for service. 
						

							36 3) With the pistol unloaded, pull the slide
rearward and engage the slide. Squeeze
the trigger and release the slide forward
simultaneously. Release pressure on the
trigger. If the trigger does not return to its
normal position, return the pistol to the
HK Service Department for service.
Squeeze the trigger and the hammer
should fall. If  the hammer does not fall,
return the pistol to the HK Service
Department for service.
4) With the pistol unloaded and the trigger
forward, apply thumb pressure to the
cocked hammer. If the hammer lowers
solely as a result of thumb pressure,
return the pistol to the HK Service
Department for service.
3.6  Function Firing
If any corrective action was accomplished, the pistol
shall be function fired a full magazine prior to being
cleaned and returned to service use.3.7  Cleaning - performed after each firing, or
every twelve (12) months, or after any exposure
to extreme environmental conditions such as
salt, fog, sand, dust, mud, water, etc.
A.  Normal Cleaning -
1. Clear the pistol!
2. Disassemble the pistol into the major assem-
bly groups.
a. Slide -
1) Scrub all internal surfaces of the slide
using the nylon brush moistened with
solvent.
2) Remove all loose fouling from all surfaces
of the slide using a rag and cotton swabs.
b. Recoil/buffer spring assembly - remove
all visible fouling using solvent, a nylon
brush, a rag, and cotton swabs.
c. Barrel with locking block -
1) Moisten the bronze bore brush with
solvent and scrub the bore from chamber
to muzzle at least six passes, back and
forth. (Note: Repeat steps 1 and 2 until a
cleaning patch can be pushed through the
bore and remains clean.) 
						

							37NOTE
All parts of the HK Mark 23 can be immersed in
any cleaning solvent that it is safe to put your
hands into. Gasoline and other motor fuels are
not authorized cleaning solvents. Avoid clean-
ing the frame in an ultrasonic cleaner as this can
remove the colored “safe” and “fire” dots.
 3.8  Inspection
During and after cleaning the operator should
inspect the pistol and its components for any
irregularities that may cause problems during its
operation.  If any potential deficiencies are noted,
they should be corrected immediately and/or
brought to the attention of the HK Service Depart-
ment for service.
A. Visually Inspect the Pistol and Magazine for:
1. Damaged or missing parts
2. Improper assembly or function
3. Absence of free movement, where applicable
4. Absence of spring tension, where applicable 2) Remove the loose fouling using cleaning
patches.
3) Scrub outside surfaces of barrel and
locking block with the nylon brush
moistened with solvent.
4) 
Scrub the threads of the barrel and O-ring
with the nylon brush moistened with
solvent.5) Remove all loose fouling using a rag and
cotton swabs.
d. Frame -
1) Scrub all internal surfaces where carbon
fouling is visible using the nylon brush
moistened with solvent. Concentrate on
the area normally covered by the slide.
2) Using the rag and cotton swabs, remove all
loose fouling from all areas of the frame.
e. Magazine -
1) The magazine is disassembled for
cleaning.
2) Scrub the top of the magazine, concen-
trating on the follower and feed lips, using
the nylon brush moistened with solvent.
3) Using the rag and cotton swabs, remove
all loose fouling from all surfaces of the
magazine. 
						

							38 5. Unaccustomed looseness
6. Parts exhibiting signs of cracks, burrs, dents,
or obvious signs of damage or stress
7. Presence of stops or tactile clicks in controls,
where applicable
8. General overall cleanliness
9. Presence of proper lubrication
10. Presence of corrosion or degradation of
      surface finish
11. Rubber hammer spur for cracks or chips
CAUTION
If the rubber hammer spur is badly cracked or
chipped, drop safety could be degraded. Pistol
should be returned to HK Service Department
to replace hammer.
3.9 Lubrication
All metal surfaces of the Mark 23 pistol have a
special surface treatment that resists all types of
corrosion including corrosion resulting from
exposure to salt water. However, this surface
treatment does not reduce friction between parts,
therefore, lubricant must be applied to the pistol.
Any type of high-quality, medium weight lubricant
(oil or grease) specifically designed for use on
firearms, such as “Break-Free” (C.L.P.), will work
well on the Mark 23 pistol.
Do not use lubricants that boast of their ability to
penetrate metal as these substances may deaden
primers.
A. Where and how much?
No Lube - (surface is dry and not slippery to the
touch)
• Plastic components
Light Lube - (finger run across surface yields
little or no lube)
• Bore, chamber, and exterior of barrel
• All metal parts
• All internal parts in slide and frame
• Magazine housing and spring
• Recoil/buffer spring assembly
• Sights
• O-ring 
						

							39 Medium Lube - (finger run across surface
yields some lube but lube does not run  down
surface when held in a vertical position)
• Barrel locking block
• Slide rails
• All operating controls
• Locking insert and guiding part
• Extractor
Heavy Lube - (Lube runs down surface when
held in a vertical position)
NOTE
No heavy lube is required on the Mark 23
pistol.
Reapply lubrication periodically during firing as it
burns off from the heat.  Apply lubricant using a
shaving brush, cotton swabs, patches, or rag. A
spray bottle also works well using compressed air to
circulate the lubricant into all parts and to remove
the excess. 
						

							40NOTE
All windage and elevation adjustments are
made using only the rear sight.
1. Windage adjustments - to adjust the
horizontal (left and right) impact of the
projectile follow these steps below:
a. Clear the Pistol!
b. Note the index mark on the rear sight and
its relationship to the index mark on the
slide.
c. Loosen the rear sight retaining screw using
a screw driver.
d. With a small hammer and brass or soft
metal drift  punch, drift the sight to the:
1) LEFT to move the point of impact to the
left.
2) RIGHT to move the point of impact to the
right.
3) The amount of movement will depend on
the individual shooter and the ammunition
used. SECTION III - ADJUSTMENT OF SIGHTS
Description -
1. The mechanical sights supplied with the Mark
23 pistol are comprised of a fixed front sight
post combined with a rear sight with u-shaped
notch of a conventional configuration. Both
front and rear sights are held in place on the
slide within a standard dovetail groove.  The
rear sight is also secured with a retaining
screw and is adjustable for windage and
elevation.
2. Both front and rear sights contain white circles
(or cylindrical tritium capsules) that appear as
dots to the operator. One dot is positioned on
either side of the rear sight aperture and in the
center of the front sight post.  When the sights
are properly aligned vertically and horizontally,
so are these dots. Thus, the three dots can be
used for rapid acquisition of the sights and
proper sight alignment.
Adjustment - the battle sight zero of the Mark 23
pistol is easily adjusted by moving or replacing
the rear sight.