The 4.2 inch M30 mortar was a rifled
muzzle-loading weapon designed for high-angle fire.
Weight (with base plate, base ring, and sighting equipment): 626 lb.
Barrel assembly: 158 lb
Standard assembly: 58 lb
Bridge assembly: 151 lb
Rotator assembly: 57 lb
Base plate: 108 lb
Base ring: 100 lb
Sighting equipment: 4 lb
Range: 6,500 yards
Ammunition: Ammunition for the M30 (T104) was issued as complete rounds, similar
to those for the 4.2 inch M2, but had extended length of cartridge container and
larger propelling charge. The round consisted of shell, fuze, propelling charge,
and ignition cartridge. When fired, the shell was stabilized in flight by
rotation transmitted to the shell by means of the pressure plate expanding the
rotating disk on the base of the shell thus forcing the disk to engage the
rifling in the bore. The shell, which had a deep cavity and suplementary charge,
was fitted with a point detonating fuze. The ignition cartridge was housed in
the cartridge container extension and was held in place by the striker nut which
contained the striker. The propelling charge consisted of a number of increments
of propellent powder in the form of square sheets assembled on the cartridge
container. When the round was inserted into the bore and released, it slid to
the bottom where the firing pin drove the striker into the primer of the
ignition cartridge. Flame from the ignition cartridge flashed through vents in
the cartridge container extension to ignite the propellant, thus firing the
round.
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