FM 23-45 Basic Field Manual
17
■34. A
CTION OF DRIVING SPRING (fig. 14).—When the rear of the bolt strikes the buffer
plate, its remaining force is absorbed in the coiled spiral spring and the buffer disks.
The force of the rearward motion of the bolt being absorbed by the buffer mechanism,
the driving spring then forces the bolt forward.
■35. F
ORWARD MOVEMENT OF BOLT (fig. 11).—When the bolt starts forward, the
extractor is guided downward by the action of the extractor feed cam on the extractor
cam plunger. This causes the extractor to force the cartridge down the T-slot in line
with the chamber. The ejector knocks the empty case from the T-slot and holds the
cartridge in line with the chamber. The upper end of the cocking lever is forced
backward, causing the lower end to move forward away from the rear of the firing If
the the pin is prematurely released, it is reengaged by the cocking lever and eased
forward so that the striker cannot contact the cartridge primer until after the breach
has been locked.
■36. R
ELEASE OF RECOILING PARTS (fig. 14) —AS the bolt goes forward its bottom
projections strike the accelerator and turn it forward. This unlocks the barrel extension
from the lock frame and releases the barrel plunger spring. When the accelerator has
F
IGURE 14.— Relation of parts in backward position.
been tripped, the barrel extension and the barrel are moved forward by the forward
force of the bolt acting through the accelerator and the expansion of the barrel plunger
spring.
■37. LOADING AND LOCKING ACTION (figs. 11 and 14) .—During the latter part of
the forward movement of the bolt, the extractor rises as the plunger moves along the
top of the extractor cam. When the extractor rises, the ejector is cammed outward,
leaving the cartridge in the chamber gripped by the T-slot. The extractor grips the first
round in the belt and is held down firmly by the cover extractor spring, ready to extract
the round. The breech lock is forced upward by the breech lock cam and locks the
breech just before the recoiling parts reach the firing position. The breech lock engages
in a recess cut in the bottom of the bolt and thus locks the bolt firmly to the barrel
extension and against the rear end of the barrel.
■38. SECOND ACT OF FEEDING (fig. 12) .—AS the bolt goes forward the stud on the
pivoted belt feed lever moves to the left in the cam groove, forcing the slide to the right.
The belt feed pawl carries the first cartridge to the right against the cartridge stops,
ready to be gripped by the extractor. The next cartridge is carried over the belt holding
pawl which rises behind it and holds it in position to be engaged by the belt feed pawl
on its next movement to the left.
■39. TRIGGER ACTION IN AUTOMATIC FIRE (figs. 9, 13, and 14).—If the trigger is
