This is a list of Turrets and Mounted Weaponry that was originally on the weapons and gear page
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M-2 Heavy Machine-gun, aka the “Ma Deuce”

Widely used by militaries around the world, the M2 heavy machine gun is a belt fed, .50 caliber machine gun based off the M1919 design. In fact, it is basically a scaled-up 1919, down to the .50 rounds it fires. It is an excellent weapon for its intended purpose: tearing humans and light vehicles into disabled messes. On soft targets, living or not, the hefty .50 rounds have a fair chance of literally ripping them in half. Your average soft skinned vehicle is likely unable to stop a short burst from the M2. Any raider vehicles will be instantly crippled with a well aimed burst to the engine block. The M2 platform was even used in the second longest combat kill with a small arm: Carlos Hathcock successfully made a kill with a special telescopically-sighted M2 at 2,286 meters in 1967-that is roughly a mile and a half!

With all this raw power, it may be hard to see how the M2 is lacking in combat. Against "shambler" zombies, however, a M2 is overkill. The .50 round 's extreeme stopping power may also create problems for these kind of targets: a disabling hit may just create another crawler to bite ones' ankle. Going up against "ragers" and raiders, the M2 is a powerful weapon and deterrent.
It will easily put down any living animal, and stop any raider vehicle short of a tank or APC.

Hard wear on parts from the .50 rounds and the availibility of the rounds themselves however mean that to anybody outside of the military, the M2 is a specialty weapon and one likely only used against vehicles.

To load an M2, open the top cover to expose the breach. Take a belt of ammunition and thread the double-loop end of the belt into the gun until the first round is seated. Place the top cover down firmly so it clicks into place. Pull the charging lever (with your palm facing up) back and let it snap forward. Pull it back and let it snap forward a second time. When the bolt-latch release is down, the gun is fully-automatic. When the release is unlocked and in the up position, the gun fires single shots only and the charging lever must be manually cocked for each shot.


Variants
Originally the M-2 was designed as a water-cooled machine gun A variant without a water jacket, but with a thicker-walled, air-cooled barrel superseded it (air-cooled barrels had already been used on variants for use on aircraft, but these quickly overheated in ground use). This new variant was then designated the M-2 HB (“HB” for “Heavy Barrel”). Due to the long procedure for changing the barrel, an improved system was developed called QCB (quick change barrel). A lightweight version, weighing 24 lb (11 kg) less- A mere 60 lb (27 kg)- Was also developed.

General Information:
The M-2 is 61½ inches long, weighs 84 pounds, with a maximum range of 4 miles (effective range 1 mile) and can burn through approximately 500 rounds per minute. It fires the .50-caliber BMG (“.50-caliber” means the diameter of the shot is ½ inch around), is recoil-operated (the recoil of the gun’s discharge causes the breach to open, which re-loads the gun) and has a muzzle velocity of approximately 2,500 ft/s. It is belt fed, meaning as long as you connect belts together, it will continue firing.

Accessories for the M-2:

M-3: Fixed position mounting of the M-2 Machine-gun. The inclusion of the Transit and Elevation (T&E) gear fixes the gun in a general area (at 100 yards it has about 100 yards play). The gear can also be repositioned in about 5 seconds. The Transit link can be set onto the transit bar without be locked down, allowing greater flexibility (at least left to right).
	M-3: Fixed Position Tripod.
M31c: This assembly allows the gun to be mounted onto a vehicle. Either the M-2 or the M-240 can be mounted with the proper carriage. (An M-2 could be mounted directly on a standard pintle, but ammo feed will be an issue.)
	M31c Vehicle Mount.
M36 Ring Mount: Allows the weapon to be mounted to the top of a vehicle, such as the 2½ ton truck, HUMVEE, etc, and could be mounted to a fixed-position, such as a bunker (though this would be a waste of the mount, as it exposes the gunner). As a general rule, the M36 is not an ideal mount.
	M36 Ring Mount.
T&E Gear: Restricts the gun’s up, down, left, and right movement, increasing accuracy by sacrificing flexibility. For the purposes intended here, the T&E gear should be set to about 100 feet beyond the gunner (or his vehicle) but with the transit bar unlocked (allowing maximum flexibility in l/r movement, but restricting u/d movement, which is the generally ideal range of flexibility for use against a skin job horde).
	Transit and Elevation (T&E) Gear.
M45 “Quadmount”: The multiple machine gun mount, often called a quadmount, was developed by the W. L. MAXON Company at the request of the U.S. Army for light anti-aircraft weapons. The turret was tested successfully and immediately adopted by the U.S. Army. The turret was originally equipped with two M-2 .5Ø cal. machine guns but quickly redesigned to mount 4 guns because of the availability of the gun. The gun mount was designed for anti-aircraft applications with a capability of a high rate of concentrated fire. The quadmount was towed behind a M-352½ ton trucks (including the M-3 Halftrack variant). In the half-track installation the mount was lifted from the trailer and placed on mounting rings. For the 2½ ton truck installation the M2Ø trailer was lifted as one unit and secured to the back of the truck. The armored pod covers the legs of the gunner. The two handles in the center of the quadmount articulate to traverse and elevate the gun and house the firing triggers. Rotating the handles forward depresses the guns, while rotating back elevates them. Pushing the left handle forward rotates the quadmount clockwise looking down while pushing the right handle forward rotates the quadmount counter-clockwise looking downward. The gun sight is located at the top of the mount. Four 2ØØ round ammunition chests are mounted next to each .5Ø cal. machine gun. Quadmounts were used in
	An M-45 on an M-2Ø trailer. both the Pacific and European theaters. As enemy aircraft became less plentiful near the end of the war, the quadmount evolved into an anti-personnel weapon. In Europe when enemy snipers were hidden in trees, it was not unusual to pull up a half-track and quadmount to counter the threat. Instead of firing at the suspected location of the snipers, the quadmount gunner would aim at the base of the trees and fire. The high concentration of projectiles would literally mow down the trees taking out the snipers along with others at the same time. In the Pacific theater, the quadmount was effective against “dug-in” Japanese positions because of its high rate and concentration of fire. It was affectionately nicknamed the “meat chopper”.
T95 Tree Mount: The chain went around the trunk and when tightened pulled the toothed saddle tight against the tree. This tree mount used a yoke to mount the gun. The T96 tree mount used the head of an M3 tripod for the platform and accepted a standard M3/M3 pintle; Whether they will accept a current M83 Carriage is another matter.
	T95 Tree Mount

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M-134 Rotatry Cannon:
This gun is used on tanks and helicopters, and is very effective against other vehicles, and hordes of zombies. IT burns through ammunition, and needs external power to spin the mechanism. But, if you manage to get lots of it, this gun can absolutely ruin other vehicles (eg. Hostile survivors, bandits), and it can eliminate hordes of zombies in 'one fell swoop', literally.
One of these, secured to a Ford F150, pick-up truck, or Aussie ute, would be the ultimate attack vehicle. Other smaller vehicles would need to be stripped before it could take one of these on it, but Holden Utes (the 2005+ models) could take this weight very easily.
It'd also be an awesome base defense gun, and if for some reason you have hostile planes above, a short burst from the Minigun would put their feet firmly on the ground. Very firmly.

Caliber:	7.62MM NATO
Number of Barrels:	6
Rate of Fire:	4,000-6,00 per minute
Weight (gun):	41.4 lbs (18.8kg)
Length:	2.6 feet (0.8m)
Recoil Force:	279 lbs (120 kg)

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MK-19 Grenade Launcher:
Commonly used on riverine assault boats and gun trucks in the US military. Somewhere in between a mortar and a machine gun the Mk. 19 has a max range of 2200 meters, each individual HEDP (High Explosive Dual Purpose) round has a fragmentation kill zone of 5 meters (15 meter injury radius) and can penetrate two inches of steel armor plating. This would destroy zombies on impact and put many down on the ground in the immediate area. While not all are killed, it would definitely turn them into manageable pieces. Obvious downsides are low availability of ammo, discretion has to be used when firing (fratricide or suicide are no-nos), very heavy (121lbs w/tripod) and lastly it can only be fired from a tripod, or mounted on a vehicle. On the same token, a MK 19 Grenade Launcher mounted on a vehicle like a ute or Ford F150 would be highly effective, allowing you to not only stop, mortar, and move again, but to fire while moving, which would be invaluable when dealing with other vehicles, if you can aim well enough. They can also be used as two-man, crew served weaps.
Trivia: The Mk-19 was developed by a USCG Warrant Officer.

To load, ensure the bolt is locked forward and the charger handles are in the up position. Open the top cover of the gun and take the first round of the belt and load it into the pawls (studs in the chamber where the grenade is seated). Slide the grenade across the pawls and push the secondary drive lever (located on the bottom of the top cover) up. Close the top cover firmly. Grasp the two charging levers on the sides of the gun and rotate them down, then pull them back until the bolt sears. Push them back forward and rotate them up to lock them. Upon pulling the trigger, the first round will load. Cock the gun again as you did before.

The charger handles MUST be up and forward when firing.
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Application:
Like current use for artillery (of any sort), post-infectious outbreak arty isn’t so much for killing skin jobs outright, as thinning massed formations of skin jobs into smaller “pockets” which are far more easily dispatched with more conventional weapons.
That should not be interpreted as an inability to kill them; A single shell of, say, Flak 38/39 landing ON a skin job will, most assuredly, make it a big pile of meaty goo over about a 150 foot area; Other skin jobs in that area will be blown to pieces as well, and even to three or four TIMES that area, many will be injured and unable to move, or move as easily, making them easier to kill when you do get there.
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Heavy Artillery:
The Flak 88 from WWII, and similar stationary artillery, has limited use against skin jobs. Humans, vulnerable to shrapnel and explosions, would be pulverized by an artillery barrage. High explosive shells could destroy fortifications and pound armor. However, against skin jobs, artillery would likely be of limited use unless carefully planned, and specifically targeting high-concentration with very-high explosives. When skin jobs are in mobs, one of the few situations where artillery would be an option, the few actually hit by artillery will likely only result in varying degrees of injuries, and few dead bodies. Large artillery almost always needs a crew of several people, in addition to actual combat troops protecting them. Artillery needs vehicles to transport the gun and ammunition, and typically a large number of guns to be effective. Though far from perfect, it can be a useful complement to a larger concern.

Artillery guns often have different methods of loading, but generally, they will be loade from the rear. Some may require a gate or door be opened to extract the empty shell case and load a new round, which is then closed and locked. The multitude of wheels are turned to change the orientation of the gun, and a simple trigger fires it. Modern guns often have computerized firing, loading, and aiming. Knowledge of the program itself is necessary to use these guns.











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MB 120mm M95 (Mortar):
A mortar is basically a hollow tube with a firing pin at the bottom. Its designed to allowed infantry to provide their own artillery support while retaining their mobility. Essentially, it launches hand grenade sized explosives over a moderately long distance. While reasonably accurate, and far more mobile then its larger counterparts, the mortar is still not very effective against zombies. Mortars can be made very easily, being very simple. No matter what you do, never try that cute trick in Saving Private Ryan where you ram the mortar round; it'll set off the round in your hand, blowing it out of your grip to land who knows where.
The above rule does have an exception: some mortar rounds have an airburst timer that allows the above trick to be utilized, but unless you're actually trained on that specific mortar and sure of the condition of the ammo, it is probably not worth the risk.

Generally, mortar shells are percussion-fired, and will go off with a forceful hit to the rear. After aiming the tube, place the shell at the end of the barrel, drop it, and quickly duck your head and cover your ears; the round will be fired out of the barrel upon reaching the bottom.














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M-240 Hammer:
Hammer is intended for rapid deployment on lightweight EOD and tactical robots such as iRobot's PackBot tactical mobile robot. The Hammer system may also be deployed on unmanned aerial vehicles, larger tactical robots, manned vehicles, and fixed installations. It consists of two AA-12 Shotguns mounted to a remotely controlled turret, which can be mounted on a vehicle or even as a fixed position weapons system ( seen here is from behind.)






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Samsung Robotic Sentry Gun:
This is the next generation of defense systems and just made for Z-Day, in 2006 Samsung announced a $200,000, all weather, 5.56mm robotic machine gun for border guarding purposes at the DMZ to North Korea. Equipped with IR and visible light cameras, it is capable of tracking multiple moving targets and is able to be under the control of a human operator.The Intelligent Surveillance and Guard Robot is able to identify and shoot a target from over 2 miles away. Twin optical and infrared sensors to identify targets from 2.5 miles in daylight and around half that distance at night. It is also equipped with communication equipment (a microphone and speakers),so that passwords can be exchanged with human troops. If the person gives the wrong password, the robot cansound an alarm or fire at the target using rubber bullets or a swivel-mounted K-3 machine gun. South Korea's 3,500 soldiers in Iraq arecurrently using robot sentries to guard home bases. I don't know who good this thing is with head-shots, but I've just seen the promovideo for this baby and it has hitten the bulls-eye with such an accuracy, that I don't think it would miss a zack's head.
Samsung makes very good hardware, and the video demonstrates its ability and it appears to be accurate as most marksmen against a non moving target, there are no demonstrations of it going up against moving targets.
What does amaze me though is the ridiculously low price of this system. Can you imagine an American Product of this category? The Phlanax CIWS is an automated anti-missle gun. But its job is a tad easier, because of missle's dead-giveaway rocket drive system, and cruise missles tend to be quite a bit larger than your average person. Larger than your average jet-liner (well, some cruise missles). But the Phlanax CIWS happens to cost 3.8 MILLION USD, per unit. Although gattling guns tend to cost 12 times more than standard weaponry used in the Samsung sentry gun, most of the Phlanax system costs are the radar and electronics Although it doesnt quite have 2 MOA, it comes close from the video. If you happen to be stinkin rich, and slightly low on large amounts of trained professionals to man your fortress, you can have a few of these systems, or even better, some of these systems but upgunned with RPG-29s (will penetrate even Modern Main Battle Tank hulls, due to tandem warheads) to knock out bandits who happened to acquire. Bradley IFVs or other armored fighting vehicles. In any other case, buy samsung electronics anyways. Its pretty good and comes at a decent price.
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M101 Common Remotely Operated Weapon Station (CROWS):
The XM101 Common Remotely Operated Weapon Station (CROWS) addresses the modernization of existing small arms weapons systems by providing for the engineering and manufacturing development of a remote mounting system for heavy and medium machine guns. The system integrates the MK19 Grenade Machine Gun, M2 Machine Gun, M240B Medium Machine Gun, and the M249 Squad Automatic Weapon (SAW). PM Soldier Weapons has near term plans to begin integration of their advanced Crew Served Weapons family, including the XM307 and XM312. The weapons operate off of a larger ammunition supply than that of the standard crew-served weapons. With larger combat loads, the weapon is reloaded less, keeping the crew inside the vehicle.
The CROWS provides the capability to remotely operate crew served weapons, improve system accuracy and operational response time by integrating state of the art drives, controls and sensors. The CROWS will also provide a baseline for a common armament platform for insertion across a variety of vehicles to reduce life cycle cost. The system will be modular and have an open architecture to permit further improvements. The system will improve aiming accuracy and maximize probability of hit against a wide variety of targets. The funded effort will provide pre-production prototype systems for the Armored Security Vehicle, Up-Armored HMMWV and Future Combat Systems (FCS) in accordance with the Current to Future transition path of the Army’s Transformation Campaign Plan (TCP).
CROWS is mounted on High Mobility Multipurpose Wheeled Vehicle (HMMWV) enables gunners to accurately engage targets viewed on a computer screen from the safety of their vehicle. CROWS allows Soldiers to operate successfully from within the safety of the Humvee’s armor, without being exposed to the threat of improvised explosive devices and small-arms fire. The improved stable platform will support most crew-served weapons and contains a sensor suite and fire control software that allows on-the-move target acquisition and first-burst target engagement. CROWS can traverse 360 degrees and go 60 degrees up and 20 degrees down. The technology used on the CROWS is a variation of the remote-controlled crew-served weapons system already used on combat vehicles like the Bradley fighting vehicle and the M-1A1 Abrams tank.
The nearly $200,000 system is designed to replace the turret gunner on Humvees to improve combat effectiveness. The system incorporates a 15-inch color monitor with live video from cameras in the daytime and thermal imaging cameras in darkness. Both cameras use a laser range finder, which allows the gunner to zoom on targets, lock onto them and maintain that lock accurately while the vehicle is in motion. The camera and the weapon can be used together or separately. The camera allows the gunner to look one way with the weapon pointed another. This feature becomes particularly useful when observing suspicious subjects from a distance, Soldiers said, adding that way people are not scared off by a weapon pointed at them.
The gun itself is controlled by a joystick which gives the gunner 100-percent functionality, allowing the operator to control the weapon with just one hand. The weapon can be aimed up to 60 degrees above and 20 degrees below in front of the vehicle and can turn a full 360 degrees, allowing the gunner to see almost any threat no matter where it is located in relation to the vehicle. With all the features used properly, the weapon can be used at 98-percent accuracy while the vehicle is in motion and the enemy on the run. The weapon is smart enough to know the vehicle’s movement, the earth’s movement and the enemy’s movements.
In December 2004 Project Manager Soldier Weapons announced execution of an Army’s Urgent Material Release for Common Remotely Operated Stations (CROWS) to support Operation Iraqi Freedom (OIF). The system was mounted on top of a HMMWV, enabling a gunner to perform missions from the safety of the inside of the armor-plated vehicle. With the use of a stabilized targeting platform, CROWS provided the Warfighter with an offensive advantage to rapidly identify, assess and engage the enemy at greater distances. The Soldier is able to view targets independent of gun elevation for MK19 super elevation and non-threatening surveillance mode. The sensor suite includes a daytime video camera, second-generation FLIR and laser rangefinder for day and night mission requirement.
The first group of 35 remotely-operated weapons for mounting on top of Humvees arrived in Iraq in early 2005 and the systems were divided among military police, Special Forces, infantry and transportation units. Military Police (MP) in Iraq operated first generation CROWS with “shoot-on-the-move” stabilization, day and night-time sensor suites and fire control capabilities to gain vantage points in challenging terrains. With a “first round on target” feature, the system also limits collateral damage.
Soldiers provided valuable operational performance and systems feedback to the project office. In a route reconnaissance mission, MPs using CROWS went out ahead of the convoy to gather intelligence and gain a vantage point. After reconnaissance of the route, they moved to an over watch position. Situated on a hill, the MP team leveraged CROWS’ high-powered sensor suites to identify a terrorist preparing to attack the convoy and instantly acquired a ballistic solution to engage him.
The product office continues to evaluate operational data from theatre and emerging data from second generation CROWS, now being tested at Aberdeen Proving Grounds (APG) in Maryland. As second generation CROWS completes developmental testing and heads towards Milestone C, The United States Army Military Police School and PM Crew Served Weapons will integrate the Soldiers’ operational assessments to drive additional improvements. Field service engineers already deployed to Iraq will continue to work alongside the Soldier to deliver vital theater support when new systems are fielded.
By late 2004 CROWS had been tested out on HMMWVs and has completed limited testing on a Fox NBC reconnaissance vehicle. It can be mounted on a range of platforms for military units with different mission profiles. Product Manager for Crew Served Weapons works with customers to define their needs, configure the platform, design the installation kit and integration requirements, conduct tests and ensure supportability. This can all be done rapidly with the user involved in the entire process.
CROWS was developed in conjunction with Recon Optical, Inc. (ROI) based in Barrington, II. The Army will be fielding over 300 systems by the end of 2006.
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GAU-8 30mm cannon

An Unmounted GAU-8.
Weight:	619.5 lb (281 kg)
Length:	252.0 in (6.40 m)
Barrel Length:	90.5 in (2.299 m)
Cartridge:	30×173MM
Barrels:	7
Action:	Electric-Motor, Hydraulic-Driven
Rate Of Fire:	3,900 rpm (rounds per minute)
Muzzle Velocity:	3,500 feet/second (1,067 m/s)
Maximum Range:	Over 4,000 ft (1,220 m)
Feed System:	Linkless Feed System

The General Electric GAU-8/A Avenger is a 30MM, hydraulically-driven seven-barrel Gatling-type rotary cannon that is mounted on the United States Air Force's A-10 Thunderbolt II. It is the largest, heaviest and most powerful aircraft cannon in the United States military. The GAU-8 was specifically designed for the anti-tank role, and delivers a very powerful round at a high rate of fire.
History: The GAU-8 was created as a parallel program with the A-X competition that produced the A-10. The specification for the cannon was laid out in 1970, with General Electric and Philco-Ford offering competing designs. Both the A-X prototypes, the A-10 and the Northrop YA-9, were designed to incorporate the weapon, although it was not available during the initial competition, and the M61 Vulcan was used as a temporary replacement. Once completed, the GAU-8 represents some 16% of the A-10 aircraft's unladen weight. The gun is placed slightly off center in the nose of the plane with the front landing gear positioned to the side. In a similar class is the Russian Gryazev-Shipunov GSh-6-30, which is lighter and has a higher fire rate but has a lower muzzle velocity and overheats faster.
The A-10 and its GAU-8/A gun entered service in 1977. The gun is no longer in production. It was produced by General Electric, though General Dynamics Armament and Technical Products has been responsible for support since 1997 when the division was sold by Lockheed Martin to General Dynamics.
The gun is loaded using Syn-Tech's linked tube carrier GFU-8/E 30 mm Ammunition Loading Assembly cart. This vehicle is unique to the A-10 and the GAU-8.
Design: The GAU-8 itself weighs 620 lb (281 kg), but the complete weapon, with feed system and drum, weighs 4,029 lb (1,830 kg) with a maximum ammunition load. It measures 19 ft ½ in (5.81 m) from the muzzle to the rearmost point of the ammunition system, and the ammunition drum alone is 34.5 in (86 cm) in diameter and 71.5 in (1.82 m) long. The magazine can hold 1,174 rounds, although 1,150 is the more normal load-out. Muzzle velocity with armor-piercing incendiary (API) ammunition is 3,250 ft/s (990 m/s), almost the same as the substantially lighter M61 Vulcan's 20 mm round.
The standard ammunition mixture for anti-armor use is a four-to-one mix of PGU-14/B Armor-Piercing Incendiary (API), with a projectile weight of about 15.0 oz (425 grams or 6,560 grains) and PGU-13/B High Explosive Incendiary (HEI) rounds, with a projectile weight of about 12.7 oz (360 grams). The PGU-14/B round incorporates a depleted uranium penetrator. The Avenger is lethal against tanks and any other armored vehicles.
A very important innovation in the design of the GAU-8/A shells is the use of aluminum alloy cases in place of the traditional steel or brass. This alone adds 30% to ammunition capacity for a given weight. The shells also have plastic driving bands to improve barrel life. They are imposing to examine and handle, measuring 11.4 in (290 mm) in length and weighing 1.53 lb (694 g) or more.
The Avenger's rate of fire was originally selectable, 2,100 rounds per minute (rpm) in the low setting, or 4,200 rpm in the high setting. Later this was changed to a fixed rate of 3,900 rpm. In practice, the cannon is limited to one and two-second bursts to avoid overheating and conserve ammunition; barrel life is also a factor, since the USAF has specified a minimum 21,000-round life for each set of barrels. It is also said that this is to deal with the substantial deceleration of the plane that results from firing (see below for details). Technically, however, there is no tech order limitation on the duration the gun may be continuously fired; therefore the pilot could, in theory, hold the trigger down and expend all rounds in the magazine one burst, with no damage or ill effects.
Each barrel is a very simple non-automatic design having its own breech and bolt. Like the original Gatling gun, the entire firing cycle is actuated by cams and powered by the rotation of the barrels. The barrels themselves are driven by the aircraft's dual hydraulic system.
The GAU-8/A ammunition is linkless, reducing weight and avoiding a great deal of potential for jamming. The feed system is double-ended: the spent casings are not ejected from the aircraft (which takes a great deal of force if the possibility of severe airframe damage is to be eliminated) but are cycled back into the ammunition drum. The feed system is based on that developed for later M61 installations, but uses more advanced design techniques and materials throughout, to save weight.

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M-242 Autocannon
Caliber:	25MM NATO.
Action:	Chain gun.
Barrel Length:	85.6 in (2.175 m).
Effective Range:	1.86 miles (3,000m).
Maximum Range:	4.23 miles (6,800m).
Maximum ROF:	200 rounds per minute.
Muzzle Velocity:	1,100 m/s (3,610 ft/s).
Total Weight:	243 lb (110 kg).

The M242 Bushmaster is a 25MM (25×137MM) belt-fed autocannon. It is used extensively by the US Armed Forces, as well as by NATO’s and some other nation’s forces in ground vehicles and watercraft. It is an externally powered, chain driven, single-barrel weapon which may be fired in semi-automatic or automatic modes. It is fed by a metallic link belt and has dual-feed capability, and uses a roller chain that drives the bolt back and forth. The weapon can destroy lightly armored vehicles and aerial targets (such as helicopters and slow-flying aircraft), and suppress enemy positions such as exposed troops, dug-in positions, and occupied built-up areas. The standard rate of fire is 200 rounds per minute. The weapon has an effective range of up to 3,000 meters, depending on the type of ammunition used.
History
The Bushmaster project started as an offshoot of the US Army’s MICV-65 program that was attempting to introduce a new infantry fighting vehicle to replace their existing M113s. Part of this program called for a new scout vehicle to replace the M114, a parallel development taking place under the XM800 Armored Reconnaissance Scout Vehicle. Both the XM800 and the cavalry version of the XM701 MICV vehicles were armed with the M139, a US-built version of the Hispano-Suiza HS.820 20 mm autocannon.
During the testing phase the Army eventually rejected the XM701 and started work on a newer design known as the XM723. Soon after the XM800 was also rejected. This led to the combination of the two programs, moving the scout role to the cavalry version of the XM723.
At the same time, the M139 proved to be disappointing (for reasons that are not well documented), and a contract for a new weapon to replace it started in 1972 at Hughes Aircraft as the Vehicle Rapid-Fire Weapons System-Successor, or VRFWS-S. This was essentially a power-driven gun firing similar ammunition as the HS.820, the power driven mechanism would ensure operation even in the case of a misfire.
Progress on the VRFWS-S was slow, and eventually resulted in a switch to a much more powerful 25MM round. Similar delays in the MICV program meant the ultimate vehicles descending from their efforts, the M2/M3 Bradley Fighting Vehicle, did not enter production until 1981, by which point the Bushmaster had matured. Since 1990, there have been several enhancements made upon the weapon, resulting in the Enhanced 25MM gun.
To date, more than 10,000 weapons are in service. One of the major reason for this popularity is the extremely reliable nature of the weapon. It has a rating of 22,000 mean rounds between failure (MRBF), much higher than many comparable devices.
Description
Unlike most automatic firearms, the M242 does not depend on gas or recoil to actuate its firing system. Instead, it uses a 1.0 hp (750 W) DC motor, positioned in the receiver to drive the chain and dual-feed system. This system uses sprockets and extractor grooves to feed, load, fire, extract, and eject rounds. A system of clutches provides for an alternate sprocket to engage and thus allows the gunner to switch between armor piercing and high explosive rounds.
The weapon assembly consists of three parts: the barrel assembly, the feeder assembly, and the receiver assembly. The three-part structure makes it possible for a single person to install or remove the system despite its considerable total weight.

The Mk-38. Note the M-242’s characteristic fluted gun barrel to reduce weight and assist cooling.

Variations
The M242 is an extremely popular weapon. It is currently in use by the The M242 is an extremely popular weapon. It is currently in use by the U.S. Army, the U. S. Navy, the U. S. Marine Corps, the United States Coast Guard, the New Zealand Army, Royal New Zealand Navy, the Norwegian Army, the Malaysian Army, the Spanish Army, the Swiss Army, the Canadian Army, the Australian Army and Navy, and the Israeli Navy as well as several others. The wide usage results in several variations and modifications on the standard M242 weapon system.
Ground Vehicles: The M242 is standard equipment on the U. S. Army M2 and M3 Bradley fighting vehicles. It is also in use on the LAV-25. Currently, the Bushmaster II 30 mm chain gun (a successor to the M242) is also in use on the Marine Corps’ Expeditionary Fighting Vehicle (EFV). The M242 is also a popular choice of primary armament for armoured fighting vehicles manufactured around the world.
Enhanced 25MM gun: Work on an upgraded weapon began in 1990. In doing so, three major systems and seven minor systems were improved. The modifications began with introducing a chrome-lined barrel, an enhanced feeder, and an enhanced receiver. The weapon systems also received minor upgrades such as quick-detachable link covers, a larger breech assembly, a high efficiency muzzle brake, longer recoil, an integral round counter, an extended life firing pin and spring, and a triple-spring drive clutch. It was first put to use on the M2A3 Bradley, the third version of the M2 Infantry Fighting Vehicle.
Aircraft: The M242 is not used on aircraft. The AC-130U and the AV-8 Harrier II use different 25MM weapons (GAU-12/U). The sister weapon of the M242, the M230 30MM chain gun, is standard equipment on the AH-64 Apache attack helicopter.
Naval: In 1977 the U. S. Navy realized that it needed a replacement for the Oerlikon/Hispano-Suiza 20MM Mk 16 series of guns. In 1986 this need was satisfied with the introduction of the Mk 38 Mod 0 weapons system. A derivative of the M242 system, the Mk 38 consists of the M242 chain gun and the Mk 88 Mod 0 machine gun mount. It provides ships with defensive and offensive gunfire capability for the engagement of a variety of surface targets. Designed primarily as a close-range defensive measure, it provides protection against patrol boats, floating mines, and various shore-based targets . The US Navy also developed a high ROF variant under the designation Mk 46 Mod 0. Recently, several US Navy platforms have been outfitted with a newer version, Mk 38 Mod 2 which includes an Electronic Optical Sight, Laser Range-Finder, FLIR, and a more reliable feeding system, enhancing the weapon systems capabilities and accuracy.
Operation
The M242 weapon system has both electrical and manual fire control and can be operated electrically or manually. In doing so, the gunner can choose from three rates of fire: (1) Single Shot Semi-Automatic, in which the gunner can shoot as fast as the trigger can be operated; (2) Low Rate Fully Automatic, in which the weapon fires 100 rounds a minute, plus or minus 25 rounds; and (3) High Rate Fully Automatic, in which the weapon fires 200 rounds a minute, plus or minus 25 rounds.
Ammunition
A wide range of ammunition has been developed for this weapon, providing it with the capability to defeat the majority of armored vehicles it is likely to encounter, up to and including some tanks. The ammunition used in the M242 may also be used in a variety of weapons such as the French Giat M811, the GAU-12, or the Oerlikon KBA weapon system. It has the capability to fire U.S. manufactured ammunition as well as the NATO equivalents thereof. Primarily though, it fires six types of rounds: the M791, M792, M793, M910, MK210, and M919.