Page 139 - FAT 105 4.17 MOODLE

Figure 13: Various action parts.

Hammer forging forms the rifling by very uniform rifling that is very hard.
hammering the drilled barrel blank Button rifling produces a higher grade
around a mandrel that features a reverse barrel than hammer forging at a price
pattern of the rifling itself. The ham- only slightly higher. Button rifling can be
mer’s impact moves the barrel’s material performed on most barrel materials.
into the mandrel and forces the bore to
Cut rifling involves pulling a single-point
conform to the rifling on the mandrel. A
cutter through a barrel and cutting one
downside to hammer forging is the intro-
shallow rifling groove at a time. Cut ri-
duction of work hardening and uneven
fling produces more uniform, precise ri-
stresses that are placed on the material.
fling, and is used in only the best match
Hammer forged barrels must undergo
grade barrels. After each pass, the barrel is
additional tempering processes to remove
indexed and another groove is cut. After
these introduced stresses. The hammer
all grooves are cut, the cutter is adjusted to
forging process creates very uniform,
make another pass. The process continues
smooth rifling and a very hard bore dur-
until all grooves are cut to depth. The cut
ing the forging process.
rifling process is more involved and time-
The button rifling process involves push- consuming than any other process, but
ing or pulling a carbide “button” through creates the best rifling possible.
the drilled blank as it rotates. The button
• Action – The action is like the engine
features several protrusions around its di-
of a firearm. The action controls a ma-
ameter shaped like a male pattern of the
jority of the cycle of operations. As pre-
rifling. The size of the protrusions be-
viously discussed, there are many action
comes progressively larger along the but-
types and operations and many variants
ton’s length. The button is used to press
of each. The most common types of ac-
or “iron” the shape of the rifling into the
tion parts are breechblocks, bolts, slides,
blank. The button rifling process work-
extractors, ejectors, and various locking or
hardens the bore of the barrel and creates
closing mechanisms.

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