wiki143 - User contributions [en]

Model rocket motor classification

2025-06-02T23:10:11Z

108.167.86.95:

{{Short description|none}}
{{More citations needed|date=July 2015}}
Motors for [[model rocket]]s<ref>NAR website: http://www.nar.org/safety-information/model-rocket-safety-code/</ref> and [[High-power rocketry|high-powered rocket]]s<ref>NAR website: http://www.nar.org/safety-information/high-power-rocket-safety-code/</ref> (together, consumer rockets) are classified by total [[impulse (physics)|impulse]] into a set of letter-designated ranges, from {{frac|1|8}}'''A''' up to '''O'''.
The total impulse is the integral of the thrust over burn time.
:<math> P_{T} = \int\limits_{0}^{t}F_{thrust}(t^{\prime})dt^{\prime} = F_{ave}t. </math>
Where <math>t</math> is the burn time in seconds, <math> F_{thrust} </math> is the instantaneous thrust in newtons, <math> F_{ave} </math> is average thrust in newtons, and <math> P_{T} </math> is the total impulse in newton seconds.
Class A is from 1.26 [[newton-second]]s (conversion factor 4.448 N per lb. force) to 2.5 N·s, and each class is then double the total impulse of the preceding class, with Class B being 2.51 to 5.00 N·s. The letter ('''M''') would represent the total impulse of between 5,120.01 and 10,240.00 N·s of impulse. Motors '''E''' and below are considered low power rocket motors. Motors between '''F''' and '''G''' are considered mid-power, while motors '''H''' and above being high-powered rocket motors. Motors which would be classified beyond O are in the realm of [[amateur rocketry]] (in this context, the term ''amateur'' refers to the rocketeer's independence from an established commercial or government organization). Professional organizations use the nomenclature of average thrust and burning time.

== Rocket motor codes ==
The designation for a specific motor looks like '''C6-3'''. In this example, the letter ('''C''') represents the total [[impulse (physics)|impulse]] range of the motor, the number ('''6''') before the dash represents the average [[thrust]] in [[newton (unit)|newton]]s, and the number ('''3''') after the dash represents the delay in seconds from propelling charge burnout to the firing of the ejection charge (a [[gas generator]] composition, usually [[black powder]], designed to deploy the recovery system). A C6-3 motor would have between 5.01 and 10 N·s of impulse, produce 6 [[newton (unit)|N]] average thrust, and fire an ejection charge 3 seconds after burnout.

An attempt was made by motor manufacturers in 1982 to further clarify the motor code by writing the total impulse in newton-seconds before the code. This allowed the burn duration to be computed from the provided numbers. Additionally, the motor code was followed by a letter designation denoting the type of propellant.<ref>USR website FS photograph: http://v-serv.com/usr/motors/images/CinerocFS5.jpg</ref> The propellant designations are manufacturer specific. This standard is still not fully adopted, with some manufacturers adopting parts or all of the additional nomenclature.

== Motor impulse by class ==

{| class="wikitable"
! align=left|   Class (Base 26)
!| Total Impulse (N·s)
!| Total Impulse (lbf·s)
!| Aerospace Vehicle or Rocket(s)
!| US Requirements
|- align="right"
|| Micro || 0–0.3125|| 0–0.07|| ||
|- align="right"
|| 1/4A || 0.3126–0.625|| 0.071–0.14|| ||
|- align="right"
|| 1/2A || 0.626–1.25|| 0.141–0.28|| ||
|- align="right"
|| A || 1.26–2.50|| 0.281–0.56|| ||
|- align="right"
|| B || 2.51–5.00|| 0.561–1.12|| ||
|- align="right"
|| C || 5.01–10.0|| 1.121–2.25|| ||
|- align="right"
|| D || 10.01–20.0|| 2.251–4.5|| ||
|- align="right"
|| E || 20.01–40.0|| 4.51–8.99|| Most Water Bottle Rockets||
|- align="right"
|| F || 40.01–80.0|| 8.991–18.0|| ||
|- align="right"
|| G || 80.01–160|| 18.01–36.0|| Invictus || Largest model rocket motor according to TRA and NAR.
|- align="right"
|| H || 160.01–320|| 36.01–71.9|| || Level 1 Certification required for purchase, available from [[Tripoli Rocketry Association|Tripoli]] or [[National Association of Rocketry|NAR]]. Under 125g propellant is Federal Aviation Administration exempt.
|- align="right"
|| I || 320.01–640|| 71.9–144|| THRUST TU-1 rocket<ref>{{Cite web |title=TU-1 Development | website=[[YouTube]] | date=14 December 2023 |url=https://www.youtube.com/watch?v=2YIaAHpn4P4 |access-date=2024-03-01}}</ref> ||
|-align="right"
|| J || 640.01–1,280|| 144.01–288|| ||Level 2 Certification required for purchase, available from [[Tripoli Rocketry Association|Tripoli]] or [[National Association of Rocketry|NAR]].
|- align="right"
|| K || 1,280.01–2,560|| 288.01–576||||
|- align="right"
|| L || 2,560.01–5,120|| 576.01–1,151|| ||
|- align="right"
|| M || 5,120.01–10,240|| 1,151.01–2,302|||| Level 3 Certification required for purchase, available from [[Tripoli Rocketry Association|Tripoli]] or [[National Association of Rocketry|NAR]].
|- align="right"
|| N || 10,240.01–20,480|| 2,302.01–4,604||High Steaks<ref>{{Cite AV media |url=https://www.youtube.com/watch?v=9UX7NJLYyb4 |title=I Cooked Meat by Launching It To Mach 3 |date=2025-05-02 |last=BPS.space |access-date=2025-05-05 |via=YouTube}}</ref>||
|- align="right"
|| O || 20,480.01–40,960|| 4,604.01–9,208||||
|- align="right"
|| P || 40,960–81,920|| 9,210–18,400||UCLA Rocket Project's Grand Larceny
NZRA - The Nike - Flight 1
|- align="right"
|| Q || 81,920–163,840|| 18,400–36,800|| NZRA - The Nike - Flight 2
|
|- align="right"
|| R || 163,840–327,680|| 36,800–73,700||USCRPL's Traveler IV<ref>{{Cite web|url=http://www.uscrpl.com/traveler-iv|title=Traveler IV|website=USCRPL|language=en-US|access-date=2019-10-16}}</ref>NZRA - The Nike - Flight 3
|
|- align="right"
|| S || 327,680–655,360|| 73,700–147,000||[[WAC Corporal]] [[Civilian Space eXploration Team|CSXT GoFast]]<ref>{{Cite web|url=http://www.astronautix.com/g/gofast.html|archive-url=https://web.archive.org/web/20161227201705/http://astronautix.com/g/gofast.html|url-status=dead|archive-date=December 27, 2016|title=GoFast|website=www.astronautix.com|access-date=2017-11-24}}</ref>|| Largest motor used by amateurs.<ref name=CSXT>{{cite web|url=http://www.ddeville.com/derek/CSXT.htm|title=Civilian Space eXploration Team}}</ref>
|-
|colspan=5|The following classifies professional propulsion systems using amateur motor codes, which are not used in industry.
|- align="right"
|| T || 655 k–1,311 k|| 147,000–295,000||ALSOR (Air Launched Sounding Rocket) || 200,000 lbf-s (889,600 N·s) is the limit for FAA definition of an "amateur" rocket <ref>{{Cite web|url=https://www.ecfr.gov/cgi-bin/text-idx?SID=2db213e14546c42a51edbee07409231c&mc=true&node=se14.1.1_11&rgn=div8|title=ECFR|access-date=2020-09-09}}</ref>
|- align="right"
|| U || 1,311 k–2,621 k|| 295,000–589,000|| [[Apollo Program|Apollo]] [[Launch Escape System|launch escape rocket]]||
|- align="right"
|| V || 2,621 k–5,243 k|| 589,000–1,180,000|| [[Bloodhound SSC|Bloodhound SSC hybrid rocket]]<ref>{{cite web |url=https://www.youtube.com/watch?v=GOKw-bHMc2w |archive-url=https://ghostarchive.org/varchive/youtube/20211213/GOKw-bHMc2w |archive-date=2021-12-13 |url-status=live|title=Falcon Project Ltd. UK Bloodhound SSC test firing |first= |last= |author= |authorlink= |date=3 October 2012 |publisher=Telegraph |accessdate=3 July 2015}}{{cbignore}}</ref>||
|- align="right"
|| W || 5,243 k–10,486 k|| 1,180,000–2,360,000|| [[S-Series (rocket family)|SS-520]]<ref name="Total vacuum impulse">[https://web.archive.org/web/20180923052249/http://www.b14643.de/Spacerockets/Specials/Impulse/index.htm Space Launch Vehicles - Total vacuum impulse]</ref> || Smallest orbital rocket<ref name="nasaspaceflights520sc">{{cite news|last1=Graham|first1=William|title=Japanese sounding rocket claims record-breaking orbital launch|url=https://www.nasaspaceflight.com/2018/02/japanese-rocket-record-borbital-launch/|accessdate=3 February 2018|agency=NASA Spaceflight|date=3 February 2018}}</ref>
|- align="right"
|| X || 10,486 k–20,972 k|| 2,360,000–4,710,000|| [[Lambda 4S]]<ref name="Total vacuum impulse" /> ||
|- align="right"
|| Y || 20,972 k–41,943 k|| 4,710,000–9,430,000|| [[Vanguard (rocket)|Vanguard]] [[Graphite-Epoxy Motor|GEM-40]] SRB [[Electron (rocket)|Electron]]<ref name="Total vacuum impulse" /> ||
|- align="right"
|| Z || 41,943 k–83,886 k|| 9,430,000–18,900,000|| [[Black Arrow]] [[Mercury-Redstone Launch Vehicle|Mercury-Redstone]]<ref name="Total vacuum impulse" /> [[Northrop Grumman Pegasus|Pegasus-XL]]<ref name="Total vacuum impulse" /> ||
|- align="right"
|| AA || 83.89 M–167.8 M|| 18,900,000–37,700,000|| [[Falcon 1]]<ref name="Total vacuum impulse" /> [[Minotaur I]]<ref name="Total vacuum impulse" /> [[VLS-1]]<ref name="Total vacuum impulse" /> ||
|- align="right"
|| AB || 167.8 M–335.5 M|| 37,700,000–75,400,000|| [[M-V]]<ref name="Total vacuum impulse" /> [[Minotaur-C]]<ref name="Total vacuum impulse" /> [[Strela (rocket)|Strela]]<ref name="Total vacuum impulse" /> ||
|- align="right"
|| AC || 335.5 M–671.1 M|| 75,400,000–151,000,000|| [[Ariane 3]]<ref name="Total vacuum impulse" /> [[LGM-25C Titan II|Titan II]] [[Dnepr (rocket)|Dnepr]]<ref name="Total vacuum impulse" /> ||
|- align="right"
|| AD || 671.1 M–1,342 M|| 151,000,000–302,000,000|| [[Vostok (rocket family)|Vostok]] [[Delta II]] [[Falcon 9 v1.0]] ||
|- align="right"
|| AE || 1,342 M–2,684 M|| 302,000,000–603,000,000|| [[Falcon 9 v1.1]] [[Falcon 9 Full Thrust]] [[Delta IV Heavy]] ||
|- align="right"
|| AF || 2,684 M–5,369 M|| 603,000,000–1,210,000,000|| [[Atlas V#Atlas V Heavy|Atlas V Heavy]] [[Falcon Heavy]] [[New Glenn]]<ref name="Total vacuum impulse" /> ||
|- align="right"
|| AG || 5.369 G–10.74 G|| 1.21*109–2.41*109|| [[Space Shuttle]] [[Saturn V]] [[Space Launch System]]||
|- align="right"
|| AH || 10.74 G–21.47 G|| 2.41*109–4.82*109|| [[Ares V]] [[Long March (rocket family)#Long March 9|Long March 9]] [[SpaceX Starship|Starship Block 1]]||
|- align="right"
|| AI || 21.47 G–42.95 G|| 4.82*109–9.64*109|| [[SpaceX Starship|Starship Block 3]]||
|- align="right"
|| AJ || 42.95 G–85.9 G|| 9.64*109–19.3*109|| [[Sea Dragon (rocket)|Sea Dragon]] [[Universal Rocket#UR-700|UR-700M]]||
|- align="right"
|}

== Governmental regulation ==
In many countries, the sale, possession, and use of model rocket motors is subject to governmental rules and regulations. High-power rockets in the United States are only federally regulated in their flight guidelines by the FAA. These regulations are codified in FAA FAR Part 101. Rockets under 125g propellant and 1500g liftoff mass are exempt from most requirements. Beyond that a free "Waiver" is required from a FAA field office.

However, some of the consumer motor manufacturers and two U.S. national rocketry organizations have established a self-regulating industry and codified it in [[National Fire Protection Association]] (NFPA) "model" code documents, which are adopted only in specific circumstances and jurisdictions, largely in conjunction with fire and building codes. This self-regulation of industry suggests a user to become certified for use before a manufacturer will sell him a motor. In the United States, the two recognized organizations that provide high-power certifications are [[Tripoli Rocketry Association]] and the [[National Association of Rocketry]]. Both these organizations have three levels of certification which involves building progressively more complex and higher powered rockets and taking a test of safety rules and regulations. With the national member association bodies using published safety codes. In Canada, the Canadian Association of Rocketry has a four-step certification process, but all three organizations accept the other's certifications if a flyer shows up at a high-power launch and wishes to fly under their sanction. Level 1 certification from NAR or TRA qualifies one to purchase and use an H or I motor, Level 2 certification J, K, and L motors, and Level 3 certification M, N, and O motors. Canada adds another step in between, and has a Level 4 which is the same as US Level 3.

In the late 1990s, the U.S. [[Bureau of Alcohol, Tobacco, Firearms and Explosives]] began requiring<ref>{{cite web |url=https://www.federalregister.gov/articles/2009/01/14/E9-578/commerce-in-explosives-amended-definition-of-propellant-actuated-device-2004r-3p |title=Commerce in Explosives--Amended Definition of Propellant Actuated Device |first= |last= |author= |authorlink= |date=13 February 2009 |publisher=Federal Register |accessdate=4 July 2015}}</ref> that individuals obtain a Low Explosives Users Permit (LEUP) to possess and use high-powered motors. On February 11, 2000, Tripoli Rocketry Association and the National Association of Rocketry filed suit in the United States District Court for the District of Columbia claiming that the BATF applied "onerous and prohibitive civil regulations" against sport rocketry hobbyists due to the Bureau's improper designation of [[ammonium perchlorate composite propellant]] (APCP) as an explosive. APCP is used in most high-power rocket motors. The commentary by BATFE staff in response to objections to adding new enforcement against hobby rocket motors is quite instructive.<ref>{{cite web |url=https://www.federalregister.gov/articles/2009/01/14/E9-578/commerce-in-explosives-amended-definition-of-propellant-actuated-device-2004r-3p#h-11 |title=Commerce in Explosives-Amended Definition of "Propellant Actuated Device" (2004R-3P) |first= |last= |author= |authorlink= |date=13 February 2009 |publisher=Federal Register |accessdate=4 July 2015}}</ref> In 2009, the court ruled in favor of the hobby organizations and ordered the BATF to remove APCP and other slow burning materials from its list of regulated explosives.<ref>{{cite web |url=http://www.v-serv.com/usr/ATFE-03-16-09.pdf |title=APCP not an explosive, rules Judge Reggie B. Walton |first= |last= |author= |authorlink= |date=16 March 2009 |publisher=Federal Judge |accessdate=3 July 2015}}</ref> That judgement established 1 meter per second burning rate ("ATFE’s own burn rate threshold for deflagration
is 1000 millimeters (or one meter) per second." Tripoli Rocketry Ass’n, 437 F.3d at 81–82) as the threshold for a material on the BATFE list of explosive materials.<ref>{{cite web |url=https://www.federalregister.gov/articles/2014/10/07/2014-23870/commerce-in-explosives-2014-annual-list-of-explosive-materials |title=2014 List of Explosive Materials (Official) |first= |last= |author= |authorlink= |date=7 October 2014 |publisher=Federal Register |accessdate=4 July 2015}}</ref>

== Vendors ==

The largest vendor of model rocket motors in the world is [[Estes Industries]]. The largest vendors of high-power rocket motors in the world are Cesaroni Technology Inc. and RCS Rocket Motor Components, Inc.

The very first model rocket motor certified was by Model Missiles Inc. (Orville Carslile). Circa 1958. The very first high-power rocket motor certified was by U.S. Rockets (Jerry Irvine). Circa 1985. The very first APCP propellant model rocket motor made was by Rocket Development Corporation (Irv Wait). Circa 1970.

The largest vendor of professional solid rockets in the world is [[Orbital ATK]].

== See also ==
* [[Jetex|Jetex (Aerodynamic lift)]]
* [[High-power rocketry]]
* [[Model rocket]]
* [[Solid-propellant rocket]]

== References ==
{{Reflist}}

== External links ==
* [http://www.nar.org/ National Association of Rocketry (NAR) - Model Rocketry and High-Powered Rocketry Certifications]
* [http://www.tripoli.org/ Tripoli Rocketry Association (TRA) - High-power rocketry Certifications]
* [http://www.canadianrocketry.org/ Canadian Association of Rocketry (CARWeb) - Model Rocketry and High-Powered Rocketry Certifications in Canada]
* [http://www.ukra.org.uk/ United Kingdom Rocketry Association - High-power rocketry Certifications]

{{DEFAULTSORT:Model Rocket Motor Classification}}
[[Category:Model rocketry]]

Heckler & Koch Mark 23

2024-12-18T01:22:01Z

108.167.86.95: /* Users */ changed Mk23 to MK23 (proper name of the firearm)

{{For|the Mark 23 Mod 0 machine gun|Stoner 63}}
{{Infobox weapon|is_ranged=yes
|name=Heckler & Koch MK 23
| image= Mark23SuppressedLeft.jpg
| image_size = 300
|caption=MARK 23 equipped with [[suppressor]] and [[Laser applications#Laser sight|laser aiming module]].
|origin=Germany
|type=[[Semi-automatic pistol]]
|cartridge=[[.45 ACP]]<ref name="miller2001"/> Can also fire [[.45 Super]] using factory parts and no modifications
|action=[[Recoil operation#Short recoil operation|Short recoil]], [[trigger (firearms)|DA/SA]], Modified Browning Action, Linkless. SA pull 4.85 lbs. (2.20 kg) and DA pull 12.13 lbs. (5.50 kg)
|service=1996–present<ref name="miller2001"/>{{Obsolete source|reason=This source is from 2001, does this apply to 2024 still?|date=February 2024}}
|used_by=See ''[[#Users|Users]]''

|designer=
|design_date=1990s<ref name="miller2001"/>
|manufacturer=[[Heckler & Koch]]<ref name="miller2001"/>
|production_date= 1991–July 2010
|number=
|variants=
* MK 23 MOD 0 (military markets)
* Mark 23/MARK 23 (civilian and law enforcement markets)
|weight=
* 1.2 kg (2.43 lb), empty<ref name=hkusa>{{cite web|url=http://www.hk-usa.com/civilian_products/mark23_specs.asp |title=HK Mark 23 Specs |url-status=dead |archive-url=https://web.archive.org/web/20140309040932/http://www.hk-usa.com/civilian_products/mark23_specs.asp |archive-date=2014-03-09 }}</ref>
* 1.47 kg (3.2 lb), loaded
* 2.29 kg (5.0 lb), loaded, with [[suppressor]] and [[Laser applications#Laser sight|LAM]]
|length=
* 245.11 mm (9.65 in), without suppressor<ref name=hkusa/>
* 421 mm (16.5 in), with suppressor
|part_length=149.10 mm (5.87 in)<ref name=hkusa/>
|width=
* 39.116 mm (1.54 in)<ref name=hkusa/>
|height=
* 150 mm (5.9 in)<ref name=hkusa/>
|rate=[[Semi-automatic firearm|Semi-automatic]]
|velocity=260 m/s (850 [[ft/s]])<ref name="miller2001"/>
|feed= Detachable box [[Magazine (firearms)|magazine]]; capacities:
* 10 rounds (''restricted'')
* 12 rounds (''standard'')<ref name=hkusa/>
* 17 rounds (''extended'')<ref>{{Cite web|url=https://hkparts.net/product/magazine-complete-17-round-red-mark-23-socom.htm|title = Magazine – Complete – 17 Round - Red – USP45 & Mark 23}}</ref>
* 20 rounds (''extended'')<ref>{{Cite web|url=https://hkparts.net/product/magazine-20-round-us-made-usp-45-mark-23-p861.htm|title = Promag Magazine - 20 Round - USP 45 & Mark 23}}</ref>
* 24 rounds (''extended'')<ref>{{Cite web|url=https://hkparts.net/product/magazine-complete-24-round-mark-23-socom.htm|title=Magazine – Complete – 24 Round – Mark 23, SOCOM}}</ref>
|range=50 m<ref>{{Cite web|url=http://www.heckler-koch.de/HKWebText/detailProd/1925/104/4/21|title=MK23 Information|access-date=2010-07-30|archive-date=2010-07-29|archive-url=https://web.archive.org/web/20100729125422/http://www.heckler-koch.de/HKWebText/detailProd/1925/104/4/21|url-status=dead}}</ref>}}

The '''Heckler & Koch MK 23''', '''MK 23 MOD 0''', '''Mark 23''', or '''USSOCOM MARK 23''' is a semi-automatic large-frame pistol chambered in [[.45 ACP]], designed specifically to be an offensive pistol. The USSOCOM version of the MK23 came paired with a [[Laser sight (firearms)|laser aiming module]] (LAM) and [[Silencer (firearms)|suppressor]]. The USSOCOM MK23 was adopted by the [[United States Special Operations Command]] (USSOCOM) for [[special operations]] units, beating out the nearest competitor, [[Colt OHWS|Colt's OHWS]]. Development of the pistol began in 1991 as special operations representatives identified the need for an "Offensive Handgun Weapons System—Special Operations Peculiar", and delivery of the pistols began in May 1996 to the special operation units.<ref>{{cite web |url=http://www.popularmechanics.com/military/a231/1281576/ |title=Weapons Of The Special Forces |date=14 September 2004 |work=[[Popular Mechanics]]}}</ref><ref>{{Cite book |url=https://books.google.com/books?id=_BJgKhwD2o4C&pg=PT278 |title=Future Weapons |first=Kevin |last=Dockery |date=4 December 2007 |publisher=Penguin|isbn=978-1-101-20618-8 |page=278}}</ref><ref>{{cite web |url=http://www.guns.com/reviews/heckler-koch-mark-23/ |title=Mark 23 -}}</ref><ref name="Kinard2003">{{cite book |last=Kinard |first=Jeff |date= 2003|title=Pistols: An Illustrated History of Their Impact |url= https://books.google.com/books?id=ZVnuHX_6bG0C|publisher=ABC-CLIO, 2003 |pages=269–270|isbn=9781851094707}}</ref>

While the USSOCOM MK23 designation usually applies to the complete system, it is also commonly used in reference to the pistol component alone. The LAM and suppressor were developed by [[Insight Technology]] and [[Knight's Armament Company]] (KAC), respectively. The civilian version of the MK23 sold by itself is designated the Mark 23.<ref>{{cite web|url=http://hk-usa.com/hk-models/mark-23/|title=MARK 23 |publisher=Heckler & Koch USA}}</ref>

==Overview==
The MK 23 is considered a [[match grade]] pistol,<ref name="Kinard2004">{{cite book|last=Kinard|first=Jeff|title=Pistols: An Illustrated History of Their Impact|url=https://books.google.com/books?id=ZVnuHX_6bG0C&pg=PA270|year=2004|publisher=ABC-CLIO|isbn=978-1-85109-470-7|pages=269–271}}</ref> and is capable of making a {{convert|2|in|mm|adj=on}} group at {{convert|25|m|yd}}.<ref>{{cite web |url=http://www.hk-usa.com/civilian_products/mark23_general.asp |title=MARK 23 |access-date=2014-04-18 |url-status=dead |archive-url=https://web.archive.org/web/20140309124324/http://www.hk-usa.com/civilian_products/mark23_general.asp |archive-date=2014-03-09 }}</ref> The MK 23 is designed for exceptional durability in harsh environments, being waterproof and corrosion-resistant.<ref name="Kinard2004"/> The [[Gun barrel|barrel]] is manufactured with [[polygonal rifling]], which is reported to improve accuracy and durability, and is much more expensive to produce.<ref name="Kinard2004"/><ref>{{cite web|url=http://precisionrifleblog.com/2014/01/02/best-rifle-barrel/|title=Best Rifle Barrel - What The Pros Use 2013 - PrecisionRifleBlog.com|website=precisionrifleblog.com|date=2014-01-03}}</ref> It also features an [[Ambidexterity|ambidextrous]] [[Safety (firearm)|safety]] and [[Magazine (firearms)|magazine]] release on both sides of the frame. The magazine release is at the rear edge of the trigger guard, which is wide enough to allow the use of gloves. A decocking lever is on the left side, which will silently lower the cocked hammer. The MK 23 is part of a larger weapon system that includes an attachable Laser Aiming Module (LAM), a [[suppressor]], and some other features such as a special high-pressure match cartridge ([[.45 ACP#Load variants|.45 +P]] ammunition).<ref name="Kinard2004"/>

The firearm was tested and found to be capable of firing tens of thousands of rounds without a barrel change.<ref name="Nigel2012">{{cite book|last=Nigel|first=Cawthorne|title=The Mammoth Book of Inside the Elite Forces|url=https://books.google.com/books?id=yXk7AAAAQBAJ&pg=PT219|year=2012|publisher=Constable & Robinson Limited|isbn=978-1-78033-731-9|pages=219–220}}</ref> It remains reliable in harsh conditions, making it suitable for use by [[special forces]]. The .45 ACP round is subsonic in the standard loading, making it suitable for use with a suppressor.<ref name="Tilstra2011">{{cite book|last=Tilstra|first=Russell C.|title=Small Arms for Urban Combat: A Review of Modern Handguns, Submachine Guns, Personal Defense Weapons, Carbines, Assault Rifles, Sniper Rifles, Anti-Materiel Rifles, Machine Guns, Combat Shotguns, Grenade Launchers and Other Weapons Systems|url=https://books.google.com/books?id=sjmNAgAAQBAJ&pg=PA13|year=2011|publisher=McFarland|isbn=978-0-7864-8875-9|page=13}}</ref>

==Development==
In 1989, [[US SOCOM]] began reviewing their equipment to see which gear fit the needs of their special [[close quarters battle]] role. Studying small arms revealed that there were 120 types and configurations of infantry weapons in different units. The logistics of getting spare parts for all these weapons was overwhelming. In response, SOCOM decided to standardize small arms among all units. One area of improvement was the pistol, undertaken by the Offensive Handgun Weapon System (OHWS) competition. It would replace pistols like the [[9 mm Parabellum|9 mm]] [[M9 pistol|M9]], which was used by regular troops as a secondary weapon. SOCOM's use of small units that operate in close means that pistols are more likely to be used as primary weapons.<ref name="sadj">[http://sadefensejournal.com/wp/?p=1947 MK23 Mod 0: The Crew-Served Pistol] - SAdefensejournal.com, 10 June 2013</ref>

The caliber for the OHWS was quickly decided not to be the NATO standard {{convert|124|gr|g|abbr=on}} 9 mm due to lack of stopping power. The [[FBI]] had selected the [[10 mm auto]] to replace their 9 mm pistols, but it was too powerful, few manufacturers produced it, and the round caused short weapon service life. The .45 ACP caliber was chosen and improved upon with the high velocity, high pressure {{convert|185|gr|g|abbr=on}} +P loading.<ref name="sadj"/>

The OHWS pistol had to fire many types of rounds in addition to the +P cartridge and have a long service life with the high pressure ammo. The [[M1911]] had been proven in service for over 70 years, but was rejected. High pressure rounds would destroy it and it did not fire reliably with a suppressor. Upgrading the M1911 would cost more than it was worth, so it was decided that they would select an entirely new design. A request for quote was for a system that included a pistol, suppressor, and laser aiming module. The pistol had to be corrosion resistant, have a high mean rounds between failures (MRBF), and be able to serve as a primary weapon.<ref name="sadj"/>

After several tests, Heckler & Koch and [[Colt's Manufacturing Company|Colt]] submissions were selected to move to phase I of the OHWS program in August 1991. They were awarded developmental contracts to produce 30 systems.<ref name="Kinard2003"/> At the time the program was beginning, HK was studying what aspects were most desirable in handguns for the U.S. civilian market. They came up with a design that had these features including reliability, durability, affordability, and others by February 1991. Colt however essentially drew upon existing technologies for their submission called the [[Colt OHWS]]. They used an M1911 frame that could accept a 10-round magazine, the decocking mechanism from the [[Colt Double Eagle]], and the rotating barrel locking system from the [[Colt 2000|All American 2000]]. The barrel of the Colt OHWS could not directly attach a suppressor, so a mounting was added to a rail in front of the handguard.<ref name="sadj"/>

Colt was eliminated after phase I, leaving only HK to move on to phase II. This phase subjected the pistols to the strictest reliability testing any pistol ever went through. The requirement was for no less than 2,000 MRBF; the HK OHWS averaged 6,027 MRBF and could reach 15,122 MRBF. Three pistols went through a 30,000-round endurance test and maintained accuracy of {{convert|2.5|in|mm|abbr=on}} at 25 meters; only the [[O-ring]] needed replacement after 20,000 rounds. The weapons worked in temperatures from -25 degrees Fahrenheit to 140 degrees Fahrenheit while exposed to mud, ice, and sand. Phase III was the awarding of a production contract to HK in June 1995. Their pistol was type classified as the Mark 23 Mod 0, and 1,950 systems were ordered at $1,186 each. All pistols were produced in Germany and the first was delivered to SOCOM on 1 May 1996.<ref name="sadj"/><ref name="HolmesShelton1997">{{cite book|last1=Holmes|first1=H. Allen|last2=Shelton|first2=Henry H.|title=U.S. Special Operations Forces: 1996 Posture Statement|url=https://books.google.com/books?id=bdo14krj6oMC&pg=PA52|year=1997|publisher=DIANE Publishing|isbn=978-0-7881-4911-5|page=52}}</ref>

Even though the Mark 23 had performed admirably, several factors worked against its use. Previous operators were trained to fire multiple 9 mm rounds and they thought firing extra rounds made up for not using harder hitting but larger and heavier .45 ACP rounds. The introduction of the smaller and lighter HK USP, political pressures, and shortages of +P ammunition also contributed against the pistol. As the [[War on Terror]] went on, operators saw the effectiveness of the .45 ACP in combat and renewed use of the Mark 23, as well as other pistols chambered for the round.<ref name="sadj"/>

==Adoption==
The MK 23 MOD 0 was built as an "offensive" handgun for U.S. [[Special forces|special operations forces]] under USSOCOM, per request made in 1989. Military versions of the firearm have the writing "MK23 USSOCOM" engraved on the [[Pistol slide|slide]].<ref name="Thompson2011">{{cite book|last=Thompson|first=Leroy|title=The Colt 1911 Pistol|url=https://books.google.com/books?id=TYSVHoBQzZYC&pg=PT103|year=2011|publisher=Osprey Publishing|isbn=978-1-84908-836-7|page=103}}</ref> The first MK 23 production models were delivered to SOCOM on May 1, 1996.<ref>Dockery, Kevin. ''Special Warfare Special Weapons: The Arms & Equipment of the UDT and SEALs from 1943 to the Present'' (Chicago: Emperor's Press), 51.</ref>

HK commercially markets the MK 23 and derivatives of it, but not the complete SOCOM system. The suppressor is made by Knight's Armament Company, and was selected over the one HK originally included as part of its entry. Insight Technology won the contract to produce the laser aiming module, later designated [[AN/PEQ-6]]. One version of the LAM produces a visible light dot, while another produces an [[infrared]] dot that can only be seen through [[night vision goggles]]. There have since been different LAM models and, at least commercially, different suppressors as well. It has been reported by some users that the cumulative effects of [[recoil]] may occasionally cause the can of the [[suppressor]] to become slightly unscrewed, but that it is relatively easy to improvise solutions for the problem.

===Civilian Mark 23===
Heckler & Koch has offered the MK 23 on the civilian market and law enforcement as the '''MARK 23'''. It is distributed by its subsidiaries HK Inc. (United States) and HKJS GmbH (Germany).<ref name="Peterson2011">{{cite book|last=Peterson|first=Philip|title=Standard Catalog of Military Firearms: The Collector's Price and Reference Guide|url=https://books.google.com/books?id=aftMDn2bd14C&pg=PA385|date=24 June 2011|publisher=F+W Media|location=Iola, Wisconsin|isbn=978-1-4402-2881-0|page=385}}</ref>

The models for the U.S. market initially came with a 10-round magazine, to comply with the U.S. [[Federal assault weapons ban|Assault Weapons Ban]].<ref name="Peterson2011"/> In 2004 the ban expired, and the civilian Mark 23 comes with the same 12-round magazine as the government variants, except in a few states that enforce their own bans on magazines larger than 10 rounds. In Canada, the Mark 23 pistol is still supplied only with 10-round magazines, as per the [[Gun politics in Canada|1995 Firearms Act]].

According to the ''Operators Manual'',<ref>[http://www.hk-usa.com/-images/shared/Mark%2023_Ops_Manual_2008.pdf MK 23 Operators Manual] {{webarchive|url=https://web.archive.org/web/20110811030250/http://www.hk-usa.com/-images/shared/Mark%2023_Ops_Manual_2008.pdf |date=2011-08-11 }}</ref> there are few differences between the civilian Mark 23 and the government MK 23. These differences are the slide engraving "Mark 23" which is only for the first half of the first year of production in 1996 (KG date code), the roll-mark "MARK 23" which is for mid 1996 to now, these instead of "MK23 USSOCOM", Matte vs shiny finish for different civilian years, tan vs black frame (500 tan ones were made), and a barrel conforming to [[Sporting Arms and Ammunition Manufacturers' Institute|SAAMI]] headspace specifications for the military vs civilian made, as the military barrels were made to allow ball ammunition to work more reliably.

==Alternatives==
In spite of its positive points, the MK 23's large size and weight have resulted in some criticism.<ref name="UsaPublications2007">{{cite book|last1=Usa|first1=Ibp|last2=Publications|first2=USA International Business|title=Us Special Operations Forces Handbook|url=https://books.google.com/books?id=BIN22d6YBrcC&pg=PA250|date=7 February 2007|publisher=Int'l Business Publications|isbn=978-1-4330-5772-4|page=250}}</ref> The handgun was designed for offense rather than defense, the size and weight intentionally incorporated to help absorb recoil forces and retain greater accuracy; but this also decreased its ease of use, comfort, and draw speed in defensive situations which require a more conventional, compact pistol.<ref>{{cite book|editor=Clifford|title=Jane's International Defense Review: IDR.|url=https://books.google.com/books?id=7lo-AQAAIAAJ|edition=4|volume=23|date=July 2002|publisher=Jane's Information Group|page=47}}</ref>

In response, HK developed the [[Heckler & Koch USP#USP Tactical|USP Tactical]] pistol based on the original USP. The USP Tactical and MK 23 look similar, although they are different pistols by design and purpose,<ref>{{Cite web|url=http://www.sadefensejournal.com/wp/?p=2894 |title=THE HECKLER & KOCH USP AND THE EVOLUTION OF THE H&K .45 AUTO CALIBER HANDGUNS |language=en |publisher=Small Arms Defence Journal |access-date=2015-12-02}}</ref> the Tactical retains much of the performance of the MK 23 without the bulky size.<ref name="Dockery2007">{{cite book|last=Dockery|first=Kevin|title=Future Weapons|url=https://books.google.com/books?id=_BJgKhwD2o4C&pg=PT278|date=4 December 2007|publisher=Penguin Group US|isbn=978-1-101-20618-8|page=278}}</ref> It uses a different suppressor (due to 16 x 1mm left handed threading, as opposed to 16 x 1mm right-handed on the MK 23). An even more compact pistol than the USP Tactical for counter-terrorist and special forces use is the [[Heckler & Koch USP#USP Compact Tactical|HK USP Compact Tactical]], which has its own optional LAM. The USP-CT is lighter and is capable of fitting a suppressor, making it a prime choice for Special Forces on covert operations. Recently, HK has developed the [[HK 45]], a much more contoured pistol based on the P2000, P8 and P30 models.

==Users==

*{{flag|Indonesia}}: ''[[Kopaska|Komando Pasukan Katak]]'' (Kopaska) tactical diver group and ''[[Kopassus|Komando Pasukan Khusus]]'' (Kopassus) special forces group.<ref name="idnvojnik">{{Cite web|url=http://www.hrvatski-vojnik.hr/hrvatski-vojnik/1612007/ind.asp |title=Kopassus & Kopaska - Specijalne Postrojbe Republike Indonezije |language=hr |publisher=Hrvatski Vojnik Magazine |access-date=2010-06-12 |url-status=dead |archive-url=https://web.archive.org/web/20100822145526/http://www.hrvatski-vojnik.hr/hrvatski-vojnik/1612007/ind.asp |archive-date=2010-08-22 }}</ref>
*{{flag|Malaysia}}: MK 23 MOD 0 adopted by [[Pasukan Gerakan Khas|Pasukan Gerakan Khas Counter-terrorism Police Squad]] of the [[Royal Malaysia Police]] and ''[[PASKAL|Pasukan Khas Laut]]'' Maritime Counter-terrorism group of the [[Royal Malaysian Navy]].<ref>{{Cite web |url=http://www.tactical-life.com/online/special-weapons/malaysian-special-forces |title=Malaysian Special Forces |author=Thompson, Leroy |date=December 2008 |publisher=Special Weapons |access-date=2010-02-10 |archive-date=2012-04-02 |archive-url=https://web.archive.org/web/20120402013858/http://www.tactical-life.com/online/special-weapons/malaysian-special-forces/ |url-status=dead }}</ref>
*{{flag|Poland}}: Used by [[GROM]].<ref>{{cite web |title=Uzbrojenie i wyposażenie |url=http://www.grom.mil.pl/uzbrojenie_pliki/UZBROJENIE.HTM |website=www.grom.mil.pl |access-date=11 November 2018 |archive-url=https://web.archive.org/web/20180108080940/http://www.grom.mil.pl/uzbrojenie_pliki/UZBROJENIE.HTM |archive-date=8 January 2018}}</ref>
*{{flag|Singapore}}: Used by the SOF, SOTF and the Special Warfare Group of the [[Republic of Singapore Navy|RSN]]
*{{flag|United States}}: Adopted by the [[United States Special Operations Command|U.S. SOCOM]]. Deliveries commenced in 1996.<ref name="miller2001">Miller, David (2001). ''The Illustrated Directory of 20th Century Guns''. Salamander Books Ltd. {{ISBN|1-84065-245-4}}.</ref>

==See also==
* [[List of individual weapons of the U.S. Armed Forces]]
* [[MEU(SOC) pistol]]—the Marine equivalent

==References==
{{Reflist}}

== Further reading ==
*''Jane's Guns Recognition Guide'' by [[Ian V. Hogg]]

==External links==
{{Commons and category|HK MK23|HK MK23}}
*[https://archive.today/20130103083350/http://www.hk-usa.com/military_products/mark23_general.asp Mark 23 Official website]
*[http://www.heckler-koch.com/no_cache/en/service/operator-manuals.html?tx_z7simpledownloads%5Bdownload%5D=542 Mark 23 Operator's Manual]
*[https://www.youtube.com/watch?v=LpODCplRodc MK 23 Video]

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{{DEFAULTSORT:Heckler and Koch Mark 23}}
[[Category:.45 ACP semi-automatic pistols]]
[[Category:Heckler & Koch pistols|MK23]]
[[Category:Silenced firearms]]
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[[Category:Semi-automatic pistols of Germany]]
[[Category:Short recoil firearms]]
[[Category:Weapons and ammunition introduced in 1991]]