Description
This fixed ammunition is used in 40mm gun cannons for firing at armored and other protected targets.
The projectile for the M81A1 cartridge consists of a hardened steel monobloc slug, crimp fitted on the blunt ogival nose with a thin steel, streamlined windshield cap to reduce aerodynamic drag. A tracer element in the base of the projectile provides a visible trace for approximately 12 seconds. In addition, some lots of these cartridges are coated on the windshield with a compound designed to leave a vapor trail for about 1,000 yards. Such lots are intended for training only and not for use in combat except for emergency. A rotating band encircles the projectile near the base. A brass or steel cartridge case filled with loose propellant is crimped to the projectile. The case has an extractor rim base, and the base contains a percussion primer consisting of a perforated tube containing black powder and a percussion element.
The windshield on the M81 is attached with an adapter rather than by crimping, and a different model primer is used.
The projectile is black with white markings.
Functioning
When the firing pin of the weapon strikes the primer, the black powder in the primer tube is ignited. Sparks flash through the tube perforations to ignite the propelling charge, and the burning propelling charge drives the projectile through the barrel with the velocity required to reach the target. Upon impact, the thin windshield crumbles, but the hardened steel slug penetrates the armor of the target.
Hazardous Components
Tracer and weight - Red (0.02 lb, 0.09 kg)
Cartridge case - M25, M25B1
Propellant and weight - M1 (0.65 lb, 0.293 kg)
Primer - M23A2, M38A1, M38B2 or Mk 22
Physical Data
Length, overall - 17.6 in, 447 mm
See Also
Nothing else to see.
Source(s)
TM 43-0001-28, Artillery Ammunition (chg 11, 2003)
TM 9-1300-203, Artillery Ammunition (1967)
TM 9-1904, Ammunition Inspection Guide (1944)
