The M103 brass cartridge cases (fig. 7-6) are
marked longitudinally or circumferentially with the
caliber/case designation on the first line. The
manufacturer symbol is on the second line. The interfix
number, lot serial number, and year of manufacture are
on the third line.
All PGU-configured cartridges are loaded with ball
spherical propellant WC 867.
M52A3B1 Electric Primer
The electric primer is used in all current PGU
configurations. It consists of an open-ended brass cup
that contains a brass button insulated from the cup by a
plastic liner. The firing pin of the gun contacts this
button. The ignition charge (a conductive explosive
mixture) is in contact with the other side of the button,
and is retained by a paper disk and a metal support cup.
The electrically initiated primer ignites the propellant
NOTE: The primer explosive element is
sensitive to electromagnetic and electrostatic
All projectiles have essentially the same external
configuration. The rotating band is copper alloy swaged
into a circumferential groove near the aft end of the
PGU-27/B Target Practice (TP)
The PGU-27/B projectile consists of a steel body
with a solid aluminum nosepiece swaged or crimped to
the steel body.
PGU-28/B Semi-Armor Piercing High Explosive
The PGU-28/B projectile consists of a steel body
with an internal cavity filled with a sponge Zirconium
pallet, composition A-4 and RS 40 incendiary mix. The
aluminum nose contains RS 41 incendiary mix and is
swaged to the steel body.
PGU-30/B Target Practice-Tracer (TP-T)
The PGU-30/B consists of a steel body with an aft
cavity containing the tracer pellet. The aluminum nose
is swaged or crimped to the steel body.
A tracer pellet is loaded into a cavity machined in
the base of the TP-T projectile used in the assembling
of the PGU-30/B cartridge. The heat and pressure of the
propelling charge ignite the tracer pellet. The tracer is
visible for approximately 3.2 seconds during projectile
PGU-27/B TARGET PRACTICE CARTRIDGE
This cartridge (fig. 7-7) has no explosive filler in
the projectile. The cartridge is used in practice firing,
for boresighting of weapons, and testing of new guns.
The projectile shape and ballistic properties are similar
to those of other PGU configuration ammunition. PGU
configuration ammunition characteristics are shown in
Approximate Unit Weight (grains)
Table 7-3.PGU Configuration Ammunition Characteristics