{{Short description|American eight-wheeled assault gun Stryker variant}} {{Redirect|M1128|the artillery round|M1128 projectile}} {{Infobox weapon | name = M1128 mobile gun system | image = Exercise Allied Spirit I, Day 5 150117-A-EM105-337.jpg | image_size = 300 | alt = | caption = A M1128 mobile gun system during a training exercise in 2015 | type = Assault gun | origin = Canada and the United States | is_artillery = yes | is_vehicle = yes <!-- Service history -->| service = | used_by = | wars = Iraq War<ref name="Army Times 10 months"/> <br /> War in Afghanistan <!-- Production history -->| designer = GM Defense of Canada, General Dynamics Land Systems | design_date = | manufacturer = General Dynamics Land Systems<ref name="micheal green">{{cite book |last=Green |first=Michael |date=22 November 2016 |title=American Wheeled Armoured Fighting Vehicles |publisher=Pen & Sword Books Ltd |location=South Yorkshire, United Kingdom |isbn=978-1473854369 |page=192 |url=https://www.bookdepository.com/American-Wheeled-Armoured-Fighting-Vehicles-Michael-Green/9781473854369 |access-date=28 May 2020}}</ref> | unit_cost = US$5.26 million (2008) | production_date = 2002–2010 | number = 142<ref name="micheal green"/> | variants = <!-- General specifications --> | spec_label = | mass = 18.77 metric tons (20.69 short tons; 18.47 long tons) | length = 6.95 m (22.92 ft) | part_length = | width = 2.72 m (8.97 ft) | height = >2.64 m (>8.72 ft)<ref>{{cite web |title=Equipment: Mobile Gun System vs. Leopard tank|website=cbc.ca|url=http://www.cbc.ca/news2/background/cdnmilitary/equipment.html}}</ref> | crew = 3 <!-- Artillery specifications -->| elevation = <!-- Vehicle/missile specifications --> | armour = 14.5x114 mm resistant<ref name="Army Fact File">{{cite web |url = http://www.army.mil/factfiles/equipment/wheeled/stryker.html |archive-url = https://web.archive.org/web/20070614040847/http://www.army.mil/factfiles/equipment/wheeled/stryker.html |url-status = dead |archive-date = June 14, 2007 |title = Army Fact File – Stryker | access-date = 2008-04-16}}</ref> | primary_armament = M68A2 105 mm cannon<ref name="Foss 2017" /> | secondary_armament = 7.62 mm machine gun; M240C coaxial machine gun; 2, M6 smoke grenade launchers | engine = Caterpillar C7 turbo diesel | engine_power = 260 kW (350 hp) | pw_ratio = 18.65 hp/ton | payload_capacity = | drive = | transmission = Automatic 6 forward, 1 reverse | suspension = 8×8 wheeled | clearance = 38 cm (15 in) | fuel_capacity = 212 liters (56 US gallons; 47 Imperial gallons) | vehicle_range = 528 km (330 mi) | speed = 96 km/h (60 mph) | guidance = | steering = }}
The '''M1128 mobile gun system (MGS)''' is an eight-wheeled assault gun of the Stryker family, mounting a 105 mm tank gun, based on the Canadian LAV III light-armored vehicle manufactured by General Dynamics Land Systems for the U.S. Army.
The MGS program emerged after the 1996 cancelation of the Army's M8 armored gun system, the service's planned replacement for the M551 Sheridan light tank.
The MGS was procured in limited numbers. It has been retired since the end of 2022 due to design and operational deficiencies.<ref name="military12may21">[https://www.military.com/daily-news/2021/05/12/army-ditching-all-of-its-stryker-mobile-gun-systems.html The Army Is Ditching All of Its Stryker Mobile Gun Systems]. ''Military.com''. 12 May 2021.</ref>
==History== thumb|right|General Motors/GDLS–Canada LAV III mobile gun system entry in the platform performance demonstration at Fort Knox {{circa}} March 2000 thumb|A mobile gun system and other Strykers shortly before being flown into Afghanistan in 2010.
===Background: replacing the Sheridan=== {{main|M551 Sheridan replacement process}}
By 1992, the armored gun system (AGS) emerged as a top priority procurement program for the Army.<ref name="top priority">{{cite news |last1=Richard |first1=Lardner |title=Service Emphasizes Lighter Forces: in New World, Armored Gun System Ranks as Army's Top Procurement Priority |url=https://www.jstor.org/stable/43987842 |access-date=23 January 2022 |work=Inside the Pentagon |issue=11 |publisher=Inside Washington Publishers |date=2 March 1992 |volume=8 |pages=1, 11–13|jstor=43987842}}</ref> The Army requested proposals for a 20-ton air-droppable light tank to replace the M551 Sheridan. The Army sought 300 AGS systems to go to the 82nd Airborne Division and the 2nd Armored Cavalry Regiment. Four competitive bids emerged.<ref name="The Four Contenders">{{cite news |title=The Contenders: Four Teams Compete for Armored Gun System Contract |url=https://www.jstor.org/stable/43987850 |access-date=23 January 2022 |work=Inside the Pentagon |issue=11 |publisher=Inside Washington Publishers |date=12 March 1992 |volume=8|page=12|jstor=43987850}}</ref> In June 1992, the Army selected the FMC Close Combat Vehicle, Light proposal.<ref name="FMC selected">{{cite news |title=Fmc Selected to Build Armored Gun System: Army's Ags to Feature All-welded Aluminum Hull, Detroit Diesel Engine |url=https://www.jstor.org/stable/43988110 |access-date=23 January 2022 |work=Inside the Pentagon |issue=24 |publisher=Inside Washington Publishers |date=11 June 1992 |volume=8 |page=13 |jstor=43988110}}</ref> This was later type-classified as the M8 armored gun system. In 1996, the Army canceled the AGS due to the service's budgetary constraints.<ref name="OSD support">{{cite news |last1=Sherman |first1=Jason |title=Service Still Seeking OSD Support: Army's Decision to Terminate AGS Meets Stiff Resistance on Capitol Hill |work=Inside the Army |issue=6 |publisher=Inside Washington Publishers |date=12 February 1996 |volume=8 |pages=1, 9–10|jstor=43982648 }}</ref>
The Iranian Revolution in the late 1970s and other Middle Eastern problems led to the Carter Doctrine, announcing that the Persian Gulf was of vital interest to the United States. In the 1980s the Rapid Deployment Joint Task Force gave way to U.S. Central Command. But it was quickly clear that heavy armoured forces (68-ton M1 Abrams and 33-ton M2/M3 Bradleys) would take too long to deploy, either by sea or air. They also needed large amounts of fuel, repair parts, and maintenance support. A more rapidly deployable and sustainable fighting vehicle was necessary.<ref>{{Cite book |last=Rottman |first=Gordon L. |url=https://books.google.com/books?id=tIelCwAAQBAJ&dq=from+the+1950s+onwards+the+US+army&pg=PA5 |title=Stryker Combat Vehicles |date=2012-09-20 |publisher=Bloomsbury Publishing |isbn=978-1-78200-490-5 |language=en}}</ref> This led to the consideration of lighter, wheeled AFVs that could be delivered faster and would be less of a supply burden.
===Interim armored vehicle competition=== {{main|Interim Armored Vehicle}} The General Dynamics mobile gun system originated from the Canadian armoured combat vehicle requirement.<ref name="trumpets" /> In partnership with General Motors, General Dynamics Land Systems (GDLS)–Canada integrated its low profile turret (LPT) onto a LAV III in January 1999.<ref name="Janes 2012" >{{cite book |editor1-last=Foss |editor1-first=Christopher F. |editor1-link=Christopher F. Foss |title=Jane's Armour and Artillery 2011–2012 |publisher=Janes Information Group |location=Surrey |year=2011 |isbn=978-0-71062-960-9 |pages=219–221 |edition=32nd |chapter=Reconnaissance Vehicles |url=https://archive.org/details/janesarmourartil0000unse}}</ref> The turret was an updated version of the one used on the GD–Teledyne Expeditionary Tank, which was entered into the Armored Gun System competition in the 1980s.<ref name="line up">{{cite news |last1=Baumgardner |first1=Neil |title=Competitors Line Up for Medium Armored Vehicle |url=https://link.gale.com/apps/doc/A57772946/ITOF?u=wikipedia&sid=bookmark-ITOF&xid=80d5b64d |access-date=18 January 2023 |work=Defense Daily |issue=35 |publisher=Access Intelligence |date=22 November 2022|volume=204 }}</ref>
In October 1999, U.S. Army Chief of Staff Eric Shinseki laid out his vision for a lighter, more transportable force. He called for mid-weight brigades that would strike a balance between heavy armor and infantry.<ref name="Vision">{{cite news |last1=MacRae |first1=Catherine |title=Service Wants to Be Lighter, Faster, More Lethal: Army Chief of Staff's 'vision' Is Focused on Medium-weight Force |url=https://www.jstor.org/stable/43995956 |access-date=7 February 2022 |work=Inside the Army |issue=41 |publisher=Inside Washington Publishers |date=14 October 1999 |volume=15 |page=6|jstor=43995956 }}</ref> The Army subsequently launched the Interim Armored Vehicle acquisition program. One of the required vehicles was the MGS. According to Shinseki, the MGS's mission differed greatly from the AGS. the AGS was also intended to be used in the anti-armor role, whereas primary targets for the MGS included bunkers, buildings, weapon positions and troops.<ref>{{cite book |author=United States Congress House Committee on Armed Services |title=Hearings on National Defense Authorization Act for Fiscal Year 2001--H.R. 4205 and Oversight of Previously Authorized Programs, Before the Committee on Armed Services, House of Representatives, One Hundred Sixth Congress, Second Session: Full Committee Hearings on Authorization and Oversight, Hearings Held February 9, 10, 17, March 15, 22, and 23, 2000 |date=2001 |publisher=U.S. Government Printing Office |isbn=978-0-16-065653-8 |page=755 |url=https://books.google.com/books?id=ECVliCA0hxEC&dq=%22M8+armored+gun+system%22&pg=PA755 |access-date=17 August 2023 |language=en}}{{PD-notice}}</ref>
A team of GM Defense of Canada and GDLS submitted a variant of the LPT assault gun to meet the MGS requirement. General Dynamics was responsible for most of the MGS.<ref name="trumpets">{{cite news |last1=Baumgardner |first1=Neil |title=General Motors Trumpets General Dynamics Deal For Meeting IAV Requirements |url=https://link.gale.com/apps/doc/A64982905/ITOF?u=wikipedia&sid=bookmark-ITOF&xid=cb5c4124 |access-date=18 January 2023 |work=Defense Daily |issue=44 |publisher=Access Intelligence |date=1 September 2000|volume=207 }}</ref>{{clarify|date=January 2023}} United Defense LP proposed an M8 armored gun system (AGS) and two variants of the mobile tactical vehicle light (MTVL), one with the AGS turret and 105mm gun, and another with a 90mm gun.<ref name="ammoshortage">{{cite news |last1=Burger |first1=Kim |title=Stockpile May Not Be Suitable for New Lav III: Army Preparing to Procure 105 mm Ammunition for New Gun System |url=https://www.jstor.org/stable/43985160 |access-date=24 January 2022 |work=Inside the Army |issue=48 |publisher=Inside Washington Publishers |date=4 December 2000 |volume=12 |pages=13–14|jstor=43985160}}</ref> Two other competing contractors submitted bids for infantry carriers, but declined to submit offers for the MGS requirement.<ref name="MGS proposed">{{cite news |last1=Burger |first1=Kim |title=Iav Source Selection May Come This Week: Chosen Vehicle Less Important Than New Concept, Observers Say |url=https://www.jstor.org/stable/43985072 |access-date=23 January 2022 |work=Inside the Army |issue=40 |publisher=Inside Washington Publishers |date=9 October 2000 |volume=12 |pages=7–9|jstor=43985072}}</ref>
Unlike the infantry carrier variant, MGS prototypes were not evaluated on the Army's proving grounds. This resulted in protests from lawmakers and industry officials. The service maintained that bid samples would be unnecessary and complicate the competition.<ref>{{cite news |last1=Burger |first1=Kim |title=Aberdeen Event Called a 'dipstick Check' Army Prepares for Iav Bid Sample Tests, Assures Controlled Setting |url=https://www.jstor.org/stable/43984790 |access-date=24 January 2022 |work=Inside the Army |issue=21 |publisher=Inside Washington Publishers |date=29 May 2000 |volume=12 |pages=1, 12|jstor=43984790}}</ref>
In September 2000, the Army told bidders it was considering plans to increase by 200 the number of MGS units purchased. Though the service did not say why it was interested in more MGS units, however ''Defense Daily'' speculated that the Army could equip light divisions with the MGS.<ref>{{cite news |last1=Baumgardner |first1=Neil |title=Army Interested In Possible Buy Of 200 Additional Mobile Gun Systems |url=https://link.gale.com/apps/doc/A65648994/ITOF?u=wikipedia&sid=bookmark-ITOF&xid=e31bb105 |access-date=18 January 2023 |work=Defense Daily |issue=63 |publisher=Access Intelligence |date=29 September 2000|volume=207 }}</ref>
In November 2000, GM–GDLS won the contract for both the infantry carrier and MGS. The MGS was later type classified as the M1128.<ref name="Schedule slip">{{cite news |last1=Burger |first1=Kim |title=LAV Variants Will Require Some Development: Testing of New Interim Vehicle May Upset Army's Fielding Schedule |url=https://www.jstor.org/stable/43985129 |access-date=6 February 2022 |work=Inside the Army |issue=46 |publisher=Inside Washington Publishers |date=20 November 2000 |volume=12 |pages=1, 6–7|jstor=43985129 }}</ref><ref name=forecast>{{cite web |title=M8 Armored Gun System - Archived 3/2004 |url=https://www.forecastinternational.com/archive/disp_pdf.cfm?DACH_RECNO=433 |website=www.forecastinternational.com |publisher=Forecast International |access-date=28 March 2019}}</ref> GM–GDLS was forced to suspend work on the IAV while the Government Accounting Office evaluated UDLP's protest of the award. GAO denied the protest in April 2001.<ref>{{cite news |last1=Winograd |first1=Erin Q. |title=GAO Releases Redacted Decision: UDLP Won't Pursue Further Action to Overturn Army's IAV Decision |url=https://www.jstor.org/stable/43985396 |access-date=23 January 2022 |work=Inside the Army |issue=18 |publisher=Inside Washington Publishers |date=7 May 2001|volume=13 |jstor=43985396}}</ref>
=== Further development and initial production === Soon after the contract was awarded, the MGS IOC date slipped two years from December 2001 to November 2003. The Army allowed GM–GDLS to substitute the Stryker ATGM variant for the MGS in the interim. In its protest, UDLP alleged that the Army had known about the schedule slippage before awarding the contract, and unfairly disregarded this in their decision making.<ref>{{cite news |last=Burger |first=Kim |title=In-lieu-of Vehicle Helped Gm-gdls Win, Company Says: Udlp Offers Additional Evidence of Army Bias in Favor of LAV III |url=https://www.jstor.org/stable/43984265 |access-date=24 January 2022 |work=Inside the Army |publisher=Inside Washington Publishers |date=15 January 2001 |pages=1, 6–7|jstor=43984265}}</ref>
GDLS delivered the first of eight pre-production mobile gun systems in July 2002.<ref name="Foss 2017" /> A Western Design ammunition handling system was chosen to replace the Ares system. Pre-production models had problems with the autoloader, and the Army solicited proposals for a replacement ammunition handling system. A system by Western Design was chosen.<ref name="Ayers" />
In March 2004, the Army approved the transfer of four AGS production vehicles to the 82nd Airborne Division to be used in Iraq. In June 2004, this plan was put on hold while the Army determined whether the MGS could meet the 82nd's requirements.<ref name="AGS MGS hold">{{cite news |title=GDLS given $500,000 to pursue air-drop test: Army to Delay Armored Gun System Delivery Until MGS Tests Complete |url=https://www.jstor.org/stable/24822615 |access-date=23 January 2022 |work=Inside Defense - Inside the Army |issue=23 |date=7 June 2004|volume=16|jstor=24822615}}</ref> In August, the Army conducted an air-drop test of a Stryker M1132 engineer squad vehicle weighted to simulate the load of the MGS. Around the same time, the Army identified issues with the air-dropability of the MGS, among the heavier of the Stryker family. Still more pervasive problems persisted with the autoloader.<ref name="MGStest">{{cite news |title=Cody: Answer Could Lie Outside Army: Army Re-evaluates Airborne Division's Request for Ags-like Platform |url=https://www.jstor.org/stable/24821748 |access-date=23 January 2022 |work=Inside Defense - Inside the Army |issue=44 |date=1 November 2004|volume=16|jstor=24821748}}</ref> In January 2005, the Army said it had ruled out fielding the AGS, saying the system lacked a sufficient inventory of spare parts that would be required to maintain the vehicle. The Army doubled down on its support for the MGS, which it said it could begin fielding in summer 2006.<ref name="Mum">{{cite news |title=Rep. Hayes Dissatisfied With Response to Query on AGS: Army Still Backing Stryker Mgs to Fill Year-old Request for Firepower |url=https://www.jstor.org/stable/24823120 |access-date=23 January 2022 |work=Inside Defense -Inside the Army |issue=6 |date=14 February 2005|volume=17|jstor=24823120}}</ref>
In October 2004, the Pentagon approved limited low-rate production of the MGS after a Defense Acquisition Board review.<ref name="LRIP"/> In December 2004, the Army awarded GDLS a $206 million contract for the production of 95 Strykers, including the first 14 limited production MGS systems.<ref name="First order">{{cite news |last1=Plummer |first1=Anne |title=Army Puts in First Order for Mobile Gun System, NBCRV Strykers |url=https://www.jstor.org/stable/24824342 |access-date=29 May 2024 |work=Inside the Army |issue=49 |publisher=Inside Washington Publishers |date=6 December 2004|volume=16 |jstor=24824342 }}</ref> During limited production, 14 vehicles were produced. During this time, General Dynamics implemented fixes to the ammunition handling system to improve reliability. In November 2004, the Pentagon approved an Army request to move the vehicle into low-rate production, for a total of 72 vehicles.<ref name="LRIP">{{cite news |last1=DiMascio |first1=Jen |title=GD to Manufacture Three MGSs this Month: Krieg Allows Mobile Gun System to Move Into Low-Rate Production |url=https://www.jstor.org/stable/24823189 |access-date=24 January 2022 |work=Inside the Army |issue=45 |publisher=Inside Washington Publishers |date=14 November 2005|volume=17 |jstor=24823189}}</ref> In August 2008, the Army awarded GDLS a $326.5 million contract for the production of 62 MGS.<ref>{{cite news |last1=Censer |first1=Marjorie |title=House Panel Cuts Funds, Raps 'Lack of Urgency': Stryker Officials to Lay Out Mobile Gun System Options at CSB Review |url=https://www.jstor.org/stable/24827234 |access-date=30 May 2024 |work=Inside the Army |date=8 September 2008 |pages=1, 8–9 |jstor=24827234 |language=en}}</ref>
In February 2008, the Pentagon approved full-rate production of the MGS after a Defense Acquisition Review.<ref>{{cite news |last1=Censer |first1=Marjorie |title=Now Awaiting Army Secretary Certification: DoD Approves Stryker Mobile Gun System for Full-rate Production |url=https://www.jstor.org/stable/24826412 |access-date=24 January 2022 |work=Inside the Army |issue=8 |publisher=Inside Washington Publishers |date=25 February 2008 |volume=20 |pages=1, 9|jstor=24826412}}</ref> The Army chose to defer full-rate production while it waited to validate fixes made to the MGS.<ref>{{cite news |last1=Marjorie |first1=Censer |title=Service to Wait for Validated Fixes: Army Defers Spending Fy-09 Funds on Stryker Mobile Gun System |url=https://www.jstor.org/stable/24830977 |access-date=24 January 2022 |work=Inside the Army |issue=33 |publisher=Inside Washington Publishers |date=24 August 2009 |volume=21 |pages=1, 8–9|jstor=24830977}}</ref> The Army deferred full-rate production in 2010.<ref>{{cite news |title=Stryker Mobile Gun System (MGS) |url=https://www.dote.osd.mil/Portals/97/pub/reports/FY2012/army/2012strykermgs.pdf?ver=2019-08-22-111733-533 |access-date=29 May 2024 |work=Director Operational Test and Evaluation |pages=119–120}}</ref><ref>Brannen, Kate. [https://archive.today/20130121092633/http://www.defensenews.com/article/20120223/DEFREG02/302230001/AUSA-U-S-Army-Plans-Post-War-Management-Stryker-Fleet?odyssey=mod_sectionstories "AUSA: U.S. Army Plans Post-War Management of Stryker Fleet."] ''Defense News''. February 23, 2012.</ref>
In 2010, GDLS began incorporating explosive reactive armor on MGS production units.<ref name="Foss 2017" />
In late 2013, the U.S. Army began seeking to reintroduce an airdroppable mobile airborne protected firepower platform to provide fire support for air assault forces, a capability that had been absent since the retirement of the Sheridan in 1997. General Dynamics initially considered modifying the wheeled Stryker MGS to meet the Mobile Protected Firepower (MPF) program requirement,<ref name="military20sept13"/><ref>[http://www.nationaldefensemagazine.org/blog/Lists/Posts/Post.aspx?List=7c996cd7-cbb4-4018-baf8-8825eada7aa2&ID=1294&Source=http%3A%2F%2Fwww%2Enationaldefensemagazine%2Eorg%2Fblog%2FLists%2FPosts%2FAllPosts%2Easpx U.S. Army in the Market for ‘Light’ Tanks] {{webarchive|url=https://web.archive.org/web/20160119075326/http://www.nationaldefensemagazine.org/blog/Lists/Posts/Post.aspx?List=7c996cd7-cbb4-4018-baf8-8825eada7aa2&ID=1294&Source=http%3A%2F%2Fwww.nationaldefensemagazine.org%2Fblog%2FLists%2FPosts%2FAllPosts.aspx |date=2016-01-19}} - Nationaldefensemagazine.org, 7 October 2013</ref> but the company instead entered a variant of the Griffin light tank.<ref>{{cite news |last1=Trevithick |first1=Joseph |title=The Army Just Selected Its First Light Tank In Decades |url=https://www.twz.com/the-army-just-selected-its-first-light-tank-in-decades |access-date=29 May 2024 |work=The War Zone |date=28 June 2022 |language=en}}</ref>
As of May 2016, 3 mobile gun systems had been written off during combat operations out of 142 produced.<ref name="Foss 2017">{{cite book |last1=Foss |first1=Christopher F. |author1-link=Christopher F. Foss |title=Jane's Land Warfare Platforms: Armoured Fighting Vehicles 2017-2018 |date=2017 |publisher=Janes Information Group |location=Surrey |isbn=978-0-71063-227-2 |pages=269–271}}</ref>
===Retirement=== [[File:M1128 Mobile Gun System Armor and Cavalry Collection.jpg|thumb|right|M1128 mobile gun system at the U.S. Army Armor and Cavalry Collection in 2023]]
In May 2021, the Army announced they would divest all mobile gun systems by the end of 2022. The decision was made following an analysis that found its autoloader had become expensive to maintain and that the M1128 had not been upgraded with a double V-hull. It was more efficient to eliminate the platform and focus on firepower improvements such as equipping Strykers with 30 mm cannons (M1296 Dragoon) and CROWS-J mounts, providing better distributed lethality capabilities that will not be lost from removing the MGS.<ref name="military12may21"/><ref>[https://www.defensenews.com/land/2021/05/12/us-army-scraps-stryker-mobile-gun-systems-in-favor-of-new-lethality-upgrades/ US Army scraps Stryker mobile gun systems in favor of new lethality upgrades]. ''Defense News''. 12 May 2021.</ref>
=== Foreign interest === Canada had liquidated about half of its fleet of Leopard 1 main battle tanks in the early 2000s.<ref>Major Howard Mark Anthony, Close Combat Vehicle and Leopard 2 Main Battle Tank: Back in the Heavyweight Fight, Canadian Forces College, pg 13, Footnote 21, https://www.cfc.forces.gc.ca/259/290/298/286/anthony.pdf Accessed 2019-11-17</ref> The Canadian Army planned to replace the MBTs with 66 mobile gun systems. However in 2007, the Canadian Army reversed itself and decided instead to procure Leopard 2.<ref name="Foss 2017" />
==Combat use== The Stryker mobile gun system saw service in the Iraq War and the War in Afghanistan.<ref name="Foss 2017" />
==Design==
===Armor and protection=== The MGS has integral all-around armor protection against 14.5×114mm AP rounds.<ref name="armor">{{cite news |title=United Defense Decides Against Taking IAV Protest To Court |url=https://link.gale.com/apps/doc/A74016924/ITOF?u=wikipedia&sid=bookmark-ITOF&xid=b5997ec6 |access-date=18 January 2023 |work=Defense Daily |issue=23 |publisher=Access Intelligence |date=2 May 2001| volume=210 }}</ref>
The MGS commander and gunner are located in the turret basket, which provides the crew some separation from the ammunition in the event of an explosion. According to a Government Accounting Office report released in May 2001, the Army had expressed doubt that this arrangement would provide "any protection from secondary explosions and fires from the main gun ammunition."<ref name="armor"/>
===Firepower=== thumb|right|Autoloader thumb|right|A mobile gun system firing in 2011
The MGS's low profile turret has a small silhouette, is stabilized and mounts a 105mm M68A1E4 or M68A2 rifled cannon with a fume extractor and an autoloader.<ref name="Janes 2012" /><ref>{{cite magazine |last1= McDonald |first1=Captain Timothy|date=September–October 2010 |title=The Mobile Gun System Platoon |magazine=Armor |volume=CXIX |issue=4 |pages= |issn=0004-2420 |url=https://d34w7g4gy10iej.cloudfront.net/pubs/pdf_33587.pdf |access-date=4 September 2025 |location=Fort Knox, KY |publisher=U.S. Army Armor Center}}</ref> The vehicle is primarily outfitted to support infantry combat operations. While it could take on some of the roles of a tank, it is not primarily intended or designed to engage in combat with main battle tanks.<ref name="Meggitt" >{{cite web |title=Stryker mobile gun system replenisher |url=https://www.meggittdefense.com/product/stryker-mobile-gun-system-replenisher/ |website=Meggitt Defense |access-date=30 July 2018}}</ref>
The MGS originally used Ares ammunition handling system (AHS). The Ares AHS was an off-the-shelf autoloader and rammer coupled to a new replenisher. The AHS used during the platform performance demonstration used a nine-round carousel autoloader and no replenisher while preproduction models used an eight-round autoloader. The first pre-production models of the MGS delivered in 2002 had difficulty with aligning rounds while transferring them from the replenisher to the autoloader. The Army directed GDLS to select a new AHS design. A General Dynamics Robotics Systems and a Western Design AHS were considered and the latter was chosen.<ref name="Ayers" /><ref name="GD Robotics">{{cite news |last1=DiMascio |first1=Jen |title=Autoloader misses reliability goals: ARMY PLANS TO REDESIGN KEY COMPONENTS OF STRYKER MOBILE GUN SYSTEM |url=https://www.jstor.org/stable/24821709 |access-date=27 September 2025 |work=Inside the Army |volume=16 |issue=42 |publisher=Inside Defense |date=2004 |pages=1–7}}</ref> The Western Design AHS replaced the replenisher to reduce the complexity of the auto-loading and replenishing mechanisms. The Ares replenisher selected in 2004 had consisted of two five-round drums, whereas the Western Design replenisher consisted of one ten-round drum.<ref name="LRIP"/><ref name="Ayers" >{{cite journal |last1=Ayers |first1=Christian C Major |title=The Stryker Mobile Gun System: A Case Study on Managing Complexity |date=June 2009 |pages=56, 61-62, 65-66, 69, 77 |url=https://apps.dtic.mil/sti/tr/pdf/ADA501145.pdf |access-date=27 September 2025 |publisher=United States Military Academy, Naval Postgraduate School}}</ref>
The MGS can store 18 rounds of main gun ammunition: 8 in the autoloader's carousel and 10 in a replenisher located at the rear of the vehicle.<ref name="Meggitt" /> It has a rate of fire of ten rounds per minute.<ref>{{Cite journal|last=Ogg|first=David|date=2001-06-18|title=The Road To The Objective Force "Armaments for the Army Transformation"|url=https://apps.dtic.mil/dtic/tr/fulltext/u2/a393782.pdf|archive-url=https://web.archive.org/web/20201105004152/https://apps.dtic.mil/dtic/tr/fulltext/u2/a393782.pdf|url-status=live|archive-date=November 5, 2020|journal=Firepower Symposium|pages=32}}</ref>
The MGS was originally developed for the Canadian Army, which did not have a requirement for transporting the vehicle via C-130. The U.S. Army did have this requirement, and so a design change was required to lower the MGS's height so that the vehicle could fit inside the aircraft. The turret was lowered within the hull.<ref name="Disappointed">{{cite news |last1=Baumgardner |first1=Neil |title=United Defense Disappointed by Cancellation of IAV Mobile Gun System Vehicle Evaluation |url=https://link.gale.com/apps/doc/A61544983/ITOF?u=wikipedia&sid=bookmark-ITOF&xid=dcb863f0 |access-date=18 January 2023 |work=Defense Daily |issue=10 |publisher=Access Intelligence |date=14 April 2000|volume=206 }}</ref> This change caused problems of its own. The reduced distance between the muzzle brake and the hull caused blast overpressures to develop. A solution was found where the "pepper pot" could be covered by a sheet of metal.<ref name="muzzle break">{{cite news |last1=Plummer |first1=Anne |title=Lowered Turret Complicates Design: After Brief Hiatus, Army Resumes Stryker Mobile Gun System Testing |url=https://www.jstor.org/stable/24820277 |access-date=24 January 2022 |work=Inside the Army |issue=29 |date=21 July 2003|volume=15 |jstor=24820277}}</ref>
The MGS's 105 mm cannon can fire four types of ammunition: the M900 kinetic energy penetrator to destroy armored vehicles; the M456A2 high-explosive anti-tank round to destroy thin-skinned vehicles and provide anti-personnel fragmentation; the M393A3 high-explosive squash head plastic round to destroy bunkers, machine gun and sniper positions, and create openings in walls for infantry to access; and M1040 canister shot for use against dismounted infantry in open terrain.<ref>[http://www.globalsecurity.org/military/systems/ground/iav-mgs.htm M1128 Stryker mobile gun system] – Globalsecurity.org</ref><ref>{{cite web |url=http://www.dtic.mil/ndia/2013armament/Hill.pdf |title=Archived copy |access-date=2014-08-22 |url-status=dead |archive-url=https://web.archive.org/web/20140826115937/http://www.dtic.mil/ndia/2013armament/Hill.pdf |archive-date=2014-08-26}}</ref>
In 2001, Rheinmetall announced that it was seeking to incorporate its 105 mm smoothbore low recoil gun on the MGS around 2004. The Army had not articulated such a requirement.<ref>{{cite news |title=Rheinmetall Offers 105mm Smoothbore Gun For Mobile Gun System Upgrade |url=https://link.gale.com/apps/doc/A79552923/ITOF?u=wikipedia&sid=bookmark-ITOF&xid=4e3b7488 |access-date=15 January 2023 |work=Defense Daily |issue=21 |publisher=Access Intelligence |date=30 October 2001| volume=212 }}</ref>
By 2000, the Army found its existing ammunition stockpile of 105 mm rounds to be in poor condition, with more than half determined to be either unusable or obsolete. The Army solicited industry to produce new ammunition to replenish the stockpile.<ref name="ammoshortage"/> L3 Communications completed low rate production of M393 high-explosive plastic HEP-T and M467 training rounds in 2004. 10,000 combat and 18,400 training rounds were ultimately produced by L3.<ref name="Foss 2017" />
====Secondary armament==== The coaxial weapon is an 7.62 mm caliber M240 machine gun. The commander's weapon is a M2 Browning 12.7 mm machine gun or a 40 mm Mk 19 grenade launcher can be mounted.<ref name="Foss 2017" />
=== Differential attributes and failures === Because the vehicle was originally designed without air conditioning (A/C), crews were given cooling vests that circulate cooled water from outside the vehicle to the garment. Vehicle computers still overheated regularly. All MGS Stryker platforms have since been upgraded with A/C units.<ref>{{cite web |title=PM (Preventive Maintenance) Keeps Strykers Combat Ready! |url=https://www.logsa.army.mil/psmag/archives/PS2017/781/781-03-05.pdf |archive-url=https://web.archive.org/web/20180730081100/https://www.logsa.army.mil/psmag/archives/PS2017/781/781-03-05.pdf |url-status=dead |archive-date=July 30, 2018 |website=Logistics Support Activity |access-date=30 July 2018}}</ref> The large weapon station and relatively smaller hatch can make emergency exits difficult.<ref name="Army Times 10 months">{{cite news |last=Cox |first=Matthew |date=4 February 2008 |title=Mobile Gun System brings the heat in Iraq |url=http://www.armytimes.com/news/2008/02/army_new_MGS_080204w/ |work=ArmyTimes |publisher=Gannett Government Media Corporation |url-status=dead |archive-url=https://archive.today/20130117051754/http://www.armytimes.com/news/2008/02/army_new_MGS_080204w/ |archive-date=January 17, 2013 |url-access=subscription |access-date=28 August 2011}}</ref>
The main cannon is separate from the crew compartment. A gun stoppage during combat can be cleared only by exiting the vehicle.{{Citation needed|date=November 2020}}
M1128 suffered of lack of reliability, excessive dead space, gun size, and gun control issues, taking its development to a limited production in 2010 with 142 units in service.<ref>{{Cite book |last=Green |first=Michael |url=https://books.google.com/books?id=3vq0DQAAQBAJ&dq=the+Stryker+Arrives+Scene&pg=PA157 |title=American Wheeled Armoured Fighting Vehicles |date=2016-10-31 |publisher=Pen and Sword |isbn=978-1-4738-5436-9 |language=en}}</ref>
===Organization=== [[File:Combined arms live fire exercise for Afghan Army 130512-A-QA210-889.jpg|thumb|US Army soldiers with M1128 MGS variant Strykers using combined arms doctrine for a modern warfare operation during the War in Afghanistan, 2013|260x260px]] As originally projected the U.S. Army allocated nine mobile gun systems (3 per infantry company) to a battalion,<ref name="Army Times 10 months"/> making for 27 mobile gun systems per "Stryker brigade" in 2013, but later the Army cut the number per brigade to 10.<ref name="military20sept13">{{cite news|last=Cox|first=Matthew|date=20 September 2013|title=Army Looks to Mount 30mm Cannons on Strykers|url=http://military.com/daily-news/2013/09/20/army-looks-to-mount-30mm-cannons-on-strykers.html?comp=7000023317828&rank=1|access-date=22 September 2013|work=Military.com}}</ref>
As of May 2017, a Stryker brigade combat team is equipped with three platoons of MGS Strykers and three platoons of ATGM Strykers in its weapons troop.<ref>{{cite web |title=Stryker Brigade Combat Team Weapons Troop |url=https://armypubs.army.mil/epubs/DR_pubs/DR_a/pdf/web/ARN3238_ATP%203-21x91%20FINAL%20WEB.pdf |website=Army Publishing Directorate |access-date=30 July 2018}}</ref>
The Army purchased 142 mobile gun systems in total.<ref>[http://breakingdefense.com/2014/01/uparmored-bradley-could-be-tough-enough-for-ampv-testers/ Uparmored Bradley Could Be Tough Enough For AMPV: Testers] - Breakingdefense.com, 29 January 2014</ref> Three were lost in combat. The Army planned to authorize 32 mobile gun systems to a Stryker Brigade Combat Team (BCT). However due to the low numbers produced, only nine were allocated to a BCT.<ref name="Foss 2017" />
A three-vehicle MGS platoon operates organic to a Stryker infantry company, with one MGS in support of a Stryker infantry platoon.<ref>[http://www.dote.osd.mil/pub/reports/FY2013/pdf/army/2013strykermgs.pdf Stryker Mobile Gun System (MGS)] {{Webarchive|url=https://web.archive.org/web/20141019191910/http://www.dote.osd.mil/pub/reports/FY2013/pdf/army/2013strykermgs.pdf |date=2014-10-19}} – Office of the Director, Operational Test & Evaluation. 2013</ref>
==See also== * {{lwc|2S14 Zhalo-S}} * {{lwc|Alvis Saladin}} * {{lwc|AMX-10 RC}} * {{lwc|AMOS}} * {{lwc|B1 Centauro}} * {{lwc|LAV-600}} * {{lwc|Panhard EBR}} * {{lwc|Rooikat}} * {{lwc|Type 08#Variants|ZTL-11}} * {{lwc|Type 16 maneuver combat vehicle}} * M1134 anti-tank guided missile vehicle, a Stryker tank destroyer variant * M8 armored gun system, a U.S. Army light tank acquisition program canceled in 1996 * MGM-166 LOSAT, a canceled U.S. Army line-of-sight missile * Mobile Protected Firepower, a U.S. Army light tank program, was cancelled in 2025 * XM1202 Mounted Combat System, a U.S. Army Future Combat Systems 20-ton tank canceled in 2011 * XM1219 armed robotic vehicle, a U.S. Army Future Combat Systems unmanned ground combat vehicle canceled in 2011
==References== {{Reflist}}
==External links== {{Commons category-inline|Stryker Mobile Gun System}}
{{Stryker}} {{Armoured combat vehicles}}
Category:Autoloaders Category:Fire support vehicles Category:Assault guns Category:Post–Cold War armored fighting vehicles of the United States Category:Armoured fighting vehicles of Canada Category:General Dynamics land vehicles Category:Wheeled armoured fighting vehicles Category:Military vehicles introduced in the 2000s Category:Mowag Piranha Category:105 mm artillery Category:Eight-wheeled vehicles