Page 157 - FAT 105 4.17 MOODLE

the drum magazine called the double drum or
Figure 6: Drum magazine.
wound up when the magazine is loaded. The
drum magazine still uses a follower, but the
design also incorporates a sprocket that is used
to separate and align the rounds inside of the
magazine’s body. As the magazine is loaded, the
rounds will push down against the follower and
cause the spiral spring to begin to wind. Once
the follower and cartridges have cleared the box
potion of the magazine and enter the drum, the
sprocket will begin to load rounds between its
teeth as it rotates with the spiral spring. Some
drum designs feature an external “crank” that
is used to assist the magazine in winding the
sprocket and spring. There is also a variant of
Figure 7: A helical magazine.
“saddle” magazine. The double drum design
combines two separate drum bodies into one
body. Both sides of the double drum function
like a conventional drum with cartridges from
each side converging into a single or double
stack in the vertical potion of the magazine’s
body. The drum magazine is typically used in
the same applications as the box magazine and
is inserted into the firearm in the same ways.
The main advantage of the drum design is that
it can hold up to 150+ rounds (depending on
caliber) in a very compact package. The biggest
disadvantages of the drum design are that they
are often quite heavy and complex.
The helical magazine gets its name from the
way the cartridges are aligned within the maga-
zine. The arrangement of the cartridges inside
the helical magazine’s body forms a helix. The
body of the magazine itself is tubular, but there
are helical-shaped fins or channels inside of the
magazine’s body, which align and organize the
cartridges. The helical magazine works similarly
to the drum magazine and even uses a spiral
spring that is wound when rounds are loaded.
The helical magazine differs from the drum
magazine in the fact that the body can hold
many more rows or ammunition than the single
row of the drum. The helical magazine also relies
on a separator instead of a sprocket to organize
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