M242 Bushmaster 25-mm cannon
The M242 Bushmaster Chain Gun is the principal US light armored vehicle main armament. Although somewhat less powerful than the 30-40-mm cannon fitted in many light combat vehicles, the M242 has proven to be reliable and potent against many types of targets.
The LAV-25 uses the Delco turret, and the M2/M3 Bradley AFV series vehicles use the TBAT-II. Several other turret designs can accommodate the M242, including Creusot-Loire T.25 (France), SAMM TTB 125 (France), Helio FVT 925 (Great Britain), Arrowpointe (South-field, Michigan), Cadillac Gage (Warren, Michigan), ESCO TAT-251 and TAT-252 (St. Louis, Missouri), and the FMC two-man autocannon turret.
The gun can fire M792 High-Explosive Incendiary with Tracer (HEI-T) and M758 Point Detonating Self-Destruct
(PDSD) fuze, M791 Armor-Piercing Discarding Sabot (APDS-T), M793 Target Practice with Tracer (TP-T), and M910 TPDS-T projectiles.
DEVELOPMENT •
Contract awarded to Hughes Helicopters (since acquired by McDonnell Douglas) in February 1976, with the first prototype beginning tests in early 1977. The gun achieved initial operational capability in 1983.
VARIANTS •
Mk 38 Sea Snake is an M242 carried in a Mk 88 gun mount and fitted in patrol craft and new-construction amphibious and auxiliary ships as general-purpose, short-range armament.
Bushmaster II is a 30-mm cannon under development; 70% of the parts are from the original Bushmaster. It fires standard GAU-8 ammunition, or RAR-DEN and KCB ammunition with modification.
COMBAT EXPERIENCE •
The Bush-master cannon was said to have been very effective against many types of soft and light armored targets during Operation
Desert Storm’s ground war in February 1991. Anecdotal reports even credited the M242 with knocking out some T-55 tanks with the APDS round. Nevertheless, some Army analysts were reported to be suggesting that the main gun be upgraded to 30- or 35-mm.
SPECIFICATIONS •
FIRING WEIGHT 244 lb (110.5 kg), barrel 95 lb (43.0 kg)
DIMENSIONS
length overall
9 ft 1 in (2.76m), gun
tube 6 ft 8 in (2.03 m)
width 12 in (330 mm)
height 15 in (380 mm)
EFFECTIVE RANGE more than 2,187 yd
(2,000 m) against BMP-1 armored
personnel carrier MUZZLE VELOCITY APDS-T M791 4,412
fps (1,345 mps); HEI-T M792 3,609
fps (1,100 mps); API-T PGU/20 3,363
fps (1,025 mps)
RATE OF FIRE 100, 200, or 500 rounds/ min, cyclic
ROUND WEIGHT API-T PGU/20 18.8 OZ
(533 g); HEI-T M792 17.7 oz (493 g); APDS-T M791 16.0 oz (454 g) with 3.7-oz (104.5-g) subprojectile
M68 105-mm tank gun
The M68 105-mm rifled gun is the American version of the British L7 gun and is the main armament of the US M60 Main
Battle Tanks (MBT) as well as the first version of the Ml Abrams. It is also the main armament of the Israeli Merkava
Mk 1 and Mk 2 MBT. In either its British or American version, the L7/M68 is the most effective tank gun of its generation and will remain a frontline weapon for the foreseeable future.
The 51-cal gun has a fume extractor and, in some installations, a thermal sleeve. The breech system is a drop-block type.
M68 Gun (on Abrams)
U.S. GOVERNMENT DEPARTMENT OF DEFENSE
The M68 fires M392 Armor-Piercing Discarding Sabot with Tracer (APDS-T), M735 and M774 Fin-Stabilized APDS-T (APFSDS-T) with tungsten penetrators,
M833 APFSDS-T with Depleted Uranium (DU) penetrator, M456 High-Explosive Antitank (HEAT), and M494 Antipersonnel with Tracer (APERS-T) projectiles. Chamberlain Manufacturing Corp. has
also developed an M900 APFSDS-T
round with a DU penetrator and the
CMC 105 APFSDS-T with a tungsten pen-
etrator (20:1 length/diameter ratio) for
export. Mecar’s M1060 APFSDS with
tungsten-nickel-iron (WNiFe) penetrator was purchased by the Saudi Army.
DEVELOPMENT •
The M68 achieved its initial operational capability in the M60 in 1962. It was produced at the Wa-tervliet Arsenal at Watervliet, New York, and in Israel.
VARIANTS •
M68A1 was a low-recoil variant developed for the FMC Close
Combat Vehicle-Light (CCV-L) and first
shown in 1985; the Benet XM35 was later adopted for the production M8 ACS.
COMBAT EXPERIENCE •
Like its British progenitor, the M68 proved very effective when used by Israeli M60 and Merkava tanks against Syrian T-72 tanks
in 1982. APFSDS rounds sliced into the
hull, hitting the carousel autoloader and detonating the ammunition with devastating results.
During the ground phase of Operation Desert Storm, which began on February
24, 1991, US Marine Corps M60Als
knocked out Iraqi T-55 and T-62 tanks in Kuwait, often firing at close range. Saudi tanks enjoyed particular success, with APFSDS ammunition believed to be the M1060 round.
SPECIFICATIONS •
FIRING WEIGHT 2,489 lb (1,128 kg),
barrel 1,662 lb (754kg)
DIMENSIONS length, overall 18 ft 3 in
(5.55 m), tube 17 ft 7 in (5.35 m), recoil 12 in (305mm)
EFFECTIVE RANGE APFSDS 90% hit
probability 2,187 yd (2,000 m)
MUZZLE VELOCITY APFSDS 4,9214,955 fps (1,500-1,510 mps); APDS 4,783 fps (1,458 mps); M456/A2 HEAT-T 3,848 fps (1,173 mps); M494
APERS-T 2,693 fps (821 mps)
RATE OF FIRE 9 rounds/min sustained
AMMUNITION ROUND WEIGHT
M494 APERS-T: 55 lb (24.94 kg)
M456/A2 HEAT-T: 48 lb (21.78 kg) M392A2 APDS-T: 41 lb (18.6 kg) APFSDS rounds 37.8-39.7 lb (17.1518 kg), APFSDS projectiles 12.7915 lb (5.8-6.83 kg) (M1060 carries
7.3-lb/3.31-kg penetrator)
M256 120-mm tank gun
The Rheinmetall-designed 120-mm, 44-cal smoothbore tank gun is the main armament for the German Leopard 2 and
US M1A1 Abrams Main Battle Tanks (MBT). The US Army’s eventual adoption of the 120-mm gun reflected a belated concern that adversary tank armor might defeat the effective but smaller
L7/M68 105-mm gun. Rheinmetall claims a 60% improvement in ballistic performance over the 105-mm.
The gun is the first heavy-caliber smoothbore gun in Western tanks, and its adoption (in preference to a rifled gun) was prompted by the desire to achieve high muzzle velocities without excessively shortening barrel life. High muzzle velocity, coupled with a higher cross-sectional loading (usually achieved by reducing the diameter of the Kinetic Energy Penetrator/KEP while retaining or increasing its mass), is currently seen as the most effective means of countering increases in armor thickness and quality.
The gun has a cold-drawn, seamless, autofrettaged tube with a chromium inner lining that improves wear resistance while firing fin-stabilized ammunition.
The gun tube’s Effective Full Charge (EFC) life was originally set at 500 rounds, but upgrades extended the life to 750 and later 1,000 EFC rounds. Both the fume extractor and thermal sleeve are made of glass-reinforced plastic. The breech type is a semiautomatic vertical sliding wedge.
There is little difference between the original Rheinmetall gun and the American M256 produced under license at the Watervliet Arsenal. The Ml turret mantlet and trunnion bearings were redesigned to accept the M256.
Ammunition for the 120-mm gun is contained in semicombustible cartridges; German and US ammunition is similar. The M256 fires the M829 Armor-Piercing Fin-Stabilized Discarding Sabot (APFSDS-T) using a Depleted Uranium (DU) penetrator and the M830 High-Explosive Antitank, Multipurpose (HEAT-MP).
Olin Corp. developed the GDI20 Kinetic Energy-Tungsten (KE-T) APFSDS-T round for export; Alliant Techsystems also has a KE-T round.
DEVELOPMENT •
Development of the Rheinmetall gun began in 1964 at the same time the Soviet T-62 introduced the first Soviet smoothbore 115-mm gun into active service. Testing of the German gun began in 1974, and production started in 1979 for the Leopard tank. Testing in the M1E1 tank began in 1981, and production of the M1A1 tank was approved in
1984. First delivery of the M1A1 with
the 120-mm gun—designated M256— occurred in 1985.
In production by Rheinmetall in Diis-seldorf, Germany, and Watervliet Arsenal, Watervliet, New York. The Rhein-metall design is also fitted in Israel’s Merkava 3, Japan’s Type 90, and Korea’s
Type 88 tank.
COMBAT EXPERIENCE •
The M256 established a convincing superiority over any other vehicle-mounted weapon during Operation Desert Storm. See Ml
Abrams.
SPECIFICATIONS •
Total system
weight 6,649 Ib (3,015 kg), gun 4,200 Ib (1,905 kg), barrel 2,590 Ib (1,175 kg)
DIMENSIONS
length overall 18 ft 4 in (5.6 m),
barrel 17 ft 5 in (5.3 m)
width 2 ft 5 in (0.73 m)
MAX EFFECTIVE RANGE (EXCEEDED IN COMBAT)
APFSDS-T: 3,281 yd (3,000 m)
HEAT-MP: 2,734 yd (2,500 m)
MUZZLE VELOCITY
APFSDS-T: 5,545-5,616 fps (1,6901,712 mps)
HEAT-MP M830: 3,740 fps (1,140
mps)
AMMUNITION ROUND
HEAT-MP M830: 53.4 Ib (24.2 kg)
with 29.8-lb (13.5-kg) projectile APFSDS M829: 41.2 Ib (18.7 kg) with
15.9-lb (7.2-kg) projectile
