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Figure 5: The cocking step in the cycle of operations.
automatically) the bolt/breech/slide will • Firing – The firing step in the cycle of
set the hammer or striker to the cocked operations releases the hammer or striker
position and compress the spring. Most and creates ignition of the cartridge.
hammers will cock on the rearward Firing requires manipulation of the fire
movement of the action, while most control group to release the hammer or
strikers will cock on the forward move- striker. When the trigger is pressed to
ment. A part called the sear is used to the rear of the firearm, the hammer or
trap the hammer/striker in the cocked striker will be released from the sear by
position. When the hammer or striker mechanical linkage.
is cocked, the sear will engage a cor-
The firing step of the cycle of operations
responding sear surface or hook on the
has its own specific sequence. When the
hammer or striker. The spring will try to
hammer or striker are released from the
force the hammer/striker forward, but
sear, their respective spring forces them
the sear will arrest any movement. When
forward. The hammer will hit the rear
the sear is moved during the firing se-
of the firing pin, driving it forward into
quence, the hammer/striker will be free
the primer of the cartridge. The striker
to move forward.
will fly forward, striking the primer
Some action types may require you to (Figure 6a).
manually cock the hammer using a pro-
When the primer is struck, a very
trusion on the rear of the hammer called
sensitive (primary) explosive is
the spur. Other action types will only
ignited. Primary explosives are
allow you to cock the hammer through
extremely sensitive to ignition
the trigger squeeze. Some striker fire
from impact, friction, heat, static
firearms will set the striker into a “set”
electricity, or electromagnetic radiation.
position without fully being cocked. The
In the case of cartridge primers, impact
trigger must be moved a small distance
creates ignition. When the firing pin
to fully cock the striker.
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