Page 109 - FAT 105 4.17 MOODLE

actions are long and short stroke piston and di- the piston and the piston housing. The
rect impingement. weight of the bolt/carrier makes for a
very robust system, which requires a
• Long Stroke Piston – The long and
greater amount of gas pressure to reliably
short stroke piston systems are so named
move the action. The weight of the sys-
because of the distance of the piston’s
tem also aids in feeding, chambering, and
travel. Typically, with a long stroke piston
locking. The increased weight equates
system the piston is attached to the bolt
to more momentum to strip the round
carrier. When the gun is fired, the high
from the magazine and drive it into the
pressure gas that has been tapped by the
chamber.
gas port acts upon the piston, driving the
piston/carrier/bolt assembly rearward.
The AK-47 is undoubtedly one of the
The long stroke piston system gets its
world’s most battle-proven, reliable, and
name from the fact that the piston and
toughest firearms ever, being fielded in
carrier move together as a single unit
every major and minor war or conflict
throughout the entire travel of the ac-
since its introduction in 1947. Much of
tion’s stroke.
the AK-47’s success is contributed to the
long stroke operating system. There is
The piston of the long stroke piston
also a large array of variants in calibers
system is often quite long, averaging
from 5.45x39 to 7.62x51 NATO that all
around 6”. The bolt/carrier assembly is
use the long stroke piston system. The
also often fairly heavy compared to other
M1 Garand, IWI Tavor, and the M249
systems because of the added weight of

Figure 32a : Long stroke piston system.

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