User Manual

Operation
Before attempting any work on your M4 make
sure that the chamber and the magazine of your
shotgun are unloaded.
(See the instructions on loading and unloading).
The M4 shotgun is a semi-automatic, tubular
magazine fed weapon chambered for the 12
gauge (18.4 mm) shotshell cartridge. The operat-
ing system employed in this weapon is the
improved ARGO (Auto-Regulating Gas Operat-
ed) Twin (two gas pistons/cylinders/ports) System
with rotating bolt head with dual locking lugs.
There are eight general steps in the operating
cycle of M4:
firing squeezing the trigger releases the
cocked hammer which strikes the
firing pin igniting the primer and
the propellant within the shell. The
expanding gases exert pressure on
all sides of the shell casing, driving
the projectile forward down the
bore. An equal amount of force is
intercepted in the gas system
unlocking actuation of the breech mechanism
that results in the opening of the
chamber
extraction removal of the cartridge case from
the chamber
ejection expulsion of the cartridge case
from the weapon
cocking the resetting of and storage of
energy in the mechanism which
provides the energy needed to
ignite the primer of the live,
chambered cartridge
feeding the transference of the live car-
tridge from the feed mechanism
in the direction of the chamber
chambering the insertion of the live cartridge
into the chamber of the weapon
locking the actuation of the breech me-
chanism that results in the clos-
ing, and sealing, of the chamber.
The shotgun is now ready to be fired.
Cartridge drop lever operation
The feeding system operates by means of a spe-
cial cartridge drop lever, the outer portion of
which protrudes below the receiver and is thus
easily reached by the trigger finger.
The hammer spring forces the cartridge drop
lever upwards to disengage it from the carrier
latch which, pulled by the carrier latch spring,
rotates clockwise to allow a cartridge to exit
from the magazine. As the cartridge falls into
position on the carrier, it presses against the car-
tridge drop lever which rotates in the opposite
direction to prevent a second cartridge from
exiting. The end of the cartridge drop lever
which protrudes from the receiver is marked
with a red point. When the red point is visible,
the hammer is cocked and the gun is ready to
fire; otherwise the hammer is not cocked.
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