Page 135 - FAT 105 4.17 MOODLE
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Figure 9: The relationship between the chamber, throat, lede, and rifling.
The extrusion process involves forcing frame/receivers may also be comprised
molten material through a specially shaped of multiple stampings that are welded
die (typically “O” shaped), which forms a together. The casting process involves
long, continuous blank when cooled. The pouring molten material into a mold and
blank is then cut to length and machined allowing it to cool. The molds are often
into its final form. Extruded frame/re- made of sand, plaster, or wax and are of-
ceivers are typically tubular or square and ten destroyed when the frame/receiver is
reserved for bolt-action-style firearms. done. Once the material has cooled, the
The injection molding process involves frame/receiver is removed, cleaned up,
forcing molten material into a specially and trimmed, and finally machined into
shaped mold. Once the material cools, its final shape.
the blank is removed from the mold and
• Barrel – The barrel of any firearm is one
the molding tabs are removed. Injection-
of the most critical components, outside
molded frames are often complete once
of the bolt/breech block/slide. The barrel
removed from the mold, or require very
(and bolt/breech block/slide) must contain
little machining and finishing. The injec-
all of the pressure and energy from the car-
tion molding process is typically reserved
tridge discharging, which can be as much
for polymer and composite materials.
as 60,000+ psi. The barrel must also stabi-
The stamping process involves thin metal lize the bullet as it passes through the bore.
sheet material that is cut and shaped by a
The barrel consists of a metal tube that
hydraulic press and dies. The press forces
may or may not be rifled. Rifling is a series
the sheet metal into shape between the
of high and low spots (lands and grooves
two dies and then trims any excess mate-
or hills and valleys) inside the bore of the
rial. When the frame/receiver is removed
barrel that extend the length of the bore
from the press it is typically complete, with
and are arranged in a helical pattern.
little to no machining required. Stamped
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