M197 Gatling gun
| M197 Gatling gun | |
|---|---|
| 250px | |
| Service history | |
| In service | 1967-present |
| Used by | United States Marine Corps |
| Production history | |
| Manufacturer | General Dynamics Armament Systems |
| Specifications | |
| Cartridge | 20 × 102 mm. |
| Caliber | 20 mm |
| Barrels | 3 |
| Rate of fire | 730 rpm |
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The M197 electric cannon is a three-barreled electric Gatling gun developed primarily for use by United States Army helicopter gunships.
Development of the M197 began in 1967 after experience in the Vietnam War revealed the inadequacy of the 7.62 mm Minigun for gunship use. The M197 is essentially a lightened version of the General Electric M61 Vulcan cannon, with three barrels instead of six. Its maximum rate of fire is one quarter that of the Vulcan, largely to limit its recoil for light aircraft and helicopter use. It shares the Vulcan's M50 and PGU series 20 mm ammunition.
The M197 went into service on later marks of the AH-1 Cobra, using either the M97 or A/A49E-7 armament subsystems, and was also fitted in a ventral turret on the U.S. Marine Corps YOV-10D Bronco NOGS. It is also the basis of the GPU-2/A gun pod, which incorporates the cannon, a battery and electric drive motor, and 300 rounds of linkless ammunition.
In the Cobra, the weapon is supplied with a magazine of 700 linked rounds, with a total capacity including feeder system of 750 rounds. It has a cyclic rate of fire of 650 rounds per minute. Standard practice is to fire the cannon in 30 to 50-round bursts.
The M197 remains in use in the latest AH-1W and AH-1Z Cobra gunships. Although the weapon's rotary drive is theoretically quite reliable, its ammunition feed has been anything but: Marine pilots initially reported an alarmingly high jam rate (sometimes greater than 30%). The USMC and the manufacturer are aware of the problem, and while no specific fix has been incorporated on the AH-1Z, an improved feed chute on the AH-1W has reduced this problem somewhat. In the meantime, crews have been trained in techniques intended to minimize the risk of jamming.
The weapon's current contractor is General Dynamics Armament Systems.
Ammunition
| Designation | Type | Projectile Weight [g] | Bursting charge [g] | Muzzle Velocity [m/s] | Description |
|---|---|---|---|---|---|
| M53 | API | ? | 4.2 g incendiary[1] | 1030 | Penetration 6.3 mm RHA at 0-degree impact and 1000-m range.[1] |
| M56A3/A4 | HEI | 102[2] | 9 g HE (RDX/wax/Al) and 1.5 g incendiary[2][1] | 1030 | Nose fuzed round, no tracer. Effective radius to produce casualties to exposed personnel 2 meters[1], fragmentation hazard out to 20 meters[2]. Penetration 12.5 mm RHA at 0 degree obliquity at 100m range [1] |
| M242 | HEI-T | ? | ? | ? | Similar to M56 series of HEI rounds, but with a tracer element.[1] |
| M246 | HEI-T | 102[2] | 8.0 g HE[2] | ? | Nose fuzed tracer round fired by M168 AA gun, self-destruct after 3 to 7 seconds of flight due to tracer burn-through. |
| M940 | MPT-SD | 105 [2] | 9 g A-4/RDX/wax[2] | 1050 | Multi-purpose fuzeless round, HE charge is initiated by the incendiary charge on the nose on impact. Self-destruct due to tracer burn-through. Penetration 12.5 mm RHA at 0 degree impact at 518 m range, or 6.3 mm at 60 degrees and 940 m. [1] |
See also
References
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