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the toggle lock action designed in During discharge, the pressure inside the
1898 and produced in 1900. The chamber will cause the locking surfaces
Luger was originally introduced in to hold it closed until the bullet/shot has
7.65x21mm Parabellum, but was exited the bore and pressure has dropped.
later offered in 9x19mm Parabellum The barrel will begin to move backward,
(Luger) and in a few very rare models driving the bolt with it. The rearward
in .45 ACP. Unlike other older action movement will force the bolt to unlock
styles that have seen a recent rebirth and move backward into the bolt body
with new models employing them, and compressing the spring between
the toggle lock action has not faired them. At this point, the inertia stored in
the same results. this spring, combined with the mass of
the bolt and body, is greater than the ac-
• Inertia Operation – The inertia op-
tion/recoil spring can hold. The spring
eration action operates similarly to the
between the bolt head and body forces
short recoil action, with one exception.
the body rearward, separating the bolt
The inertia-operated action relies on
body and head once more.
both recoil forces and the inertia these
forces create in the action to complete As the bolt body continues rearward, it
the cycling process. Like the long recoil will pull the bolt head with it, which also
action, the inertia-operated action is extracts and ejects the empty case and
used primarily by shotguns. cocks the hammer. On its forward stroke,
the bolt head will strip a fresh round
The inertia operation action utilizes a
from the elevator/shell lifter and feed
two-piece bolt head/body design that
and seat it into the chamber. The bolt
collapses, and a short recoiling barrel.
head will rotate, aligning the locking lugs
The bolt head and body are forced apart
and locking the chamber.
by a spring between them. Most modern
inertia-operated systems also rely on a
rotating bolt system, similar to the bolt-
action, to lock the breech.
Figure 28: An inertia-operated action.
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