Description
These 175mm HE Projectiles M437A2 and M437A1 are high explosive rounds for the 175mm Gun Cannon M113 used for fragmentation, blast, and mining in support of ground troops and armored columns.
The projectile consists of a hollow steel forging with a boat tailed base, a streamlined ogive, a gilding metal rotating band, and a nylon obturating band. A base cover is welded to the base of the projectile for added protection against the entrance of hot gases from the propelling charge during firing. The nose of the projectile is fitted with a threaded eyebolt lifting plug to facilitate handling and provide a closure for the fuze cavity. The projectile is made with a deep fuze cavity and may be loaded with TNT or Composition B. Deep cavity projectiles contain a supplementary charge in the fuze cavity. A cardboard spacer is placed in the fuze cavity between the supplementary charge and the lifting plug to limit movement of the supplementary charge during shipping and handling. The rotating band is protected by a removable grommet.
The M437A2 is filled with Composition B. The M437A1 is filled with TNT.
The projectile is olive drab with yellow markings.
Functioning
When the weapon is fired, Primer M82 ignites the igniter pad of the propelling charge. The burning pad ignites the black powder in the core assembly. Sparks and flame flash through perforations in the igniter core tubes in a pattern designed to assure uniform ignition of the propellant increments. Bore wear in the gun is reduced by an additive jacket assembled to Increment 3 when firing at full charge. Gases generated by the burning propellant force the projectile through the gun tube with the velocity required to reach the target. The rotating band engages the barrel rifling to impart spin for stabilization in flight. The obturating band expands to prevent leakage of gas pressure past the projectile, and is discarded on leaving the weapon. Depending upon the type fuze employed, the projectile is detonated either on impact or on approach to the target.
Hazardous Components
Filler, M437A2 - Comp B (31 lb, 14.1 kg)
Supplementary charge, M437A2 - TNT (0.30 lb, 0.14 kg)
Filler, M437A1 - TNT (30 lb, 13.6 kg)
Supplementary charge, M437A1 - TNT (0.30 lb, 0.14 kg)
Propelling charge - M86 series
Primer - M82
Physical Data
Length, overall - 34.1 in, 866.1 mm
See Also
Propelling Charge, 175mm, M86, M86A1, M86A2
Source(s)
TM 9-1300-203, Artillery Ammunition (1967)
