range of 1,100 meters. Range changes may be made by
fired, the parts of the machine gun function in a certain
using either the slide release or the elevating knob. The
sequence. Many of the actions occur simultaneously
slide release is used for making major changes in
and are only separated for teaching purposes. The
elevation. The elevating knob is used for fine
sequence of operation is known as the cycle of
adjustments, such as during zeroing. Four clicks on the
operation.
elevating knob equal a 1-mil change of elevation. The
For ease of understanding, the complete cycle of
sight is adjustable for windage 5 mils right and left of
operation is discussed in the following eight steps:
zero. The windage knob is located on the left side of the
sight. One click on the windage knob equals a 1-mil
1. Feeding: A round is positioned in the feed tray
change of deflection.
groove.
2. Chambering: Around is stripped from the belt
NOTE
and placed in the chamber.
3. Locking: The bolt is locked inside the barrel
1 mil equals 1 inch at 1,000 inches, 1 yard at
socket.
1,000 yards, 1 meter at 1,000 meters, and so on.
4. Firing: The firing pin strikes and initiates the
A safety lever located on the left side of the trigger
primer of the cartridge.
housing has an S (SAFE) position and an F (FIRE)
5. Unlocking: The bolt is unlocked from the barrel
position. When the safety lever is in the SAFE position,
socket.
the bolt cannot be pulled to the rear or released to go
forward. The cocking lever, on the right side of the gun,
6. Extracting: The empty case is pulled from the
is used to pull the bolt to the rear. It must be returned
chamber.
manually to its FORWARD position each time the bolt
7. Ejecting: The empty cartridge case is thrown
is manually pulled to the rear.
from the receiver.
Operation
8. Cocking: The sear engages the sear notch.
The cycle starts when a round is put into the feed
The machine gun is designed to function
tray groove and the trigger is pulled, releasing the sear
automatically as long as ammunition is fed into the gun
and the trigger is held to the rear. Each time a round is
from the sear notch (fig. 2-46). It stops when the trigger
Figure 2-46.--The sear disengaging from the sear notch.
2-25
