The HK MK 23 and the HK Mark 23 .45 ACP pistols give shooters match grade accuracy
equal to that of the finest custom made handguns - yet they exceed the most stringent operational requirements ever demanded of a combat handgun. The MK 23/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 MK 23/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 Offensive Handgun and is available in limited numbers. Designated the "Mark 23", it is almost identical
to the MK23, MOD 0 pistol used by the Special Operations Command, right down to its
threaded barrel. The principal differences are slide inscriptions (Mark 23 as opposed to
MK 23) and a barrel manufactured to SAAMI headspace specifications. Commercial Mark 23
pistols come supplied with 10-round magazines. Military and law enforcement models have
12-round magazines like the Special Operations model.
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
Operations Forces Offensive Handgun Weapon System, consisting of a caliber .45 pistol,
detachable sound and flash suppressor, and laser aiming module (LAM). The barrel is
threaded to accept accessories such as a flash and sound suppressor and the unique HK
polygonal bore profile increases muzzle velocity and service life, reduces bore fouling,
and eases cleaning. Molded into the frame are special accessory grooves for attaching
a light or laser aimer. However, the suppressor and LAM are not being developed by HK
and cannot be obtained from Heckler & Koch.
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 with an average of 1.4 inches extreme 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 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. All pistols
exceeded the 2000 MRBS with an average of 6000 MRBS.
In more than 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. 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 0-ring on the barrel that seals the barrel in the slide until
unlocking, led to this remarkable achievement. The 0-ring lasts bevond 20,000 rounds and
can be replaced by the operator without tools in seconds.
To meet operational environmental requirements, the pistol was function tested at +140
and -25° F, exposed to 2 hours of submersion in sea water at 66 feet, placed in
surf, salt-fog, sand-dust, mud, icing, unlubricated, and fouled environments. A special
maritime surface coating protected the pistol from any corrosion, in all of these
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 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 actuated without adjustment of the firing grip using the
firing hand thumb or index finger.
Other notable features include a mechanical recoil reduction system that reduces
recoil forces to the shooter and components of the pistol by as much as 30%, a
reinforced polymer frame, a one-piece machined steel slide, and a law
enforcement/military capacity of thirteen rounds (twelve rounds in the magazine,
one in the chamber).
The weapon is aimed using either iron sights or an optional laser aiming component
(currently under development). The iron sights provide a 3-dot sight picture with
white or optional self-luminous tritium dots.
The Heckler & Koch Special Operations Handgun is designed to fire a minimum of
30,000 rounds of +P ammunition prior to depot level maintenance. After depot level
maintenance, the pistol must have at least 30,000 rounds ofadditional service life on
the slide and frame.
The MK 23 became the first caliber .45 ACP pistol to 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.