This document discusses factors that influence the spread of a machine gun's cone of fire and beaten zone, including range, terrain, and firing position. It describes different types of fires with respect to the ground (plunging and grazing), target (frontal, oblique, flanking, enfilade), and machine gun (fixed, traversing, searching, traverse and search, swinging traverse, free gun). It also defines sustained, rapid, and cyclic rates of fire for a machine gun.

1. Machine Gun Theory
TC 3-22.249 MAY 2017

2. Cone of Fire and Beaten Zone

3. What factors into the spread of the cone of fire &
beaten zone?
● Length of burst
● Recoil management by the shooter
● External Ballistics
● Range to target
○ As range increases, beaten zone becomes shorter and wider
○ As range decreases, beaten zone becomes longer and narrower
● Slope of terrain
○ On rising ground, beaten zone becomes shorter
○ On ground sloping away from the shooter, beaten zone becomes longer

4. Fires With Respect to the Ground - Plunging Fires
Plunging Fires - Plunging fire occurs when there is little or no danger space from
the muzzle of the weapon to the beaten zone.
● Plunging fires happen when soldiers fire weapons at long range
● When they fire from high ground to low ground
● When they fire into abruptly rising ground,
● When they fire across uneven terrain, which results in a loss of grazing fire at
points along the trajectory

5. Plunging Fires

6. Fires With Respect to the Ground - Grazing Fires
Grazing Fires - When the center of the cone of fire does not rise more than one
meter above the ground. Grazing fire is possible only when the terrain is level or
sloping uniformly.
● Employed fires on the final protective line
● Grazing fire range for light/medium machine guns is 600m
● Grazing fire range for heavy machine guns is 700m

7. Grazing Fire

8. Check On Learning
When does plunging fire occur?
Fires into abruptly rising ground, fires from high to low ground, fires at long range
and across uneven terrain.
How high off the ground is the center of the cone of fire for grazing fire?
Grazing fire ≤ 1 meter off the ground

9. Fires With Respect to Target
The objective of fires in their respect to target is to maximize the effectiveness of
the beaten zone with respect to the formation and direction of movement of the
target being engaged.

10. Frontal Fire

11. Oblique Fire
● Occurs when the long axis of the beaten zone
is at an angle other than perpendicular or
parallel to target (between 0 and 90 degrees)

12. Flanking Fire
● Occurs when the long axis of the beaten
zone is perpendicular to the direction of
travel of the target.

13. Enfilade Fire
● Occurs when the long axis of the beaten zone
coincides with the long axis of the target.
● Direction of travel is irrelevant to enfilade fire.
● Enfilade fire may coincide with all types of
fires with respect to target.

14. Check on Learning
There is a file formation moving towards you from your 12 o’clock, which fire will
you employ?
Frontal (Enfilade)
There is a line formation moving to your right perpendicular to you, which fire will
you employ?
Flanking (Enfilade)

15. Fires With Respect to Machine Gun - Fixed
● Used when beaten zone covers the area of a target
with no manipulation in elevation or direction.

16. Traversing Fire
● Used when minor changes are needed in
direction for the beaten zone to cover the area of
a target.

17. Searching Fires
● Used when changes in elevation are needed for the
beaten zone to cover the area of a target depending on
range and terrain(slope).

18. Traverse and Search Fire
● Used when minor changes in elevation and direction
are needed for the beaten zone to cover the area of a
target.
● Often used for oblique fires.

19. Swinging Traverse Fire
● Used when major changes in direction are
needed to engage a target.
● Doesn’t have a true single beaten zone.

20. Free Gun
● Used when major adjustments are needed in
both elevation and direction to engage
targets.
● Doesn’t have a true single beaten zone.

22. Rates of Fire
● Sustained
○ Conserves ammunition and requires infrequent barrel changes
○ May not be high enough volume of fire to keep enemy suppressed
● Rapid
○ Places an exceptionally high volume of fire on an enemy position
○ Used to suppress the enemy quickly and to quickly gain fire superiority
○ Requires use of more ammunition and more frequent barrel changes
● Cyclic
○ Gunner holds the trigger to the rear
○ Used primarily in FPL
○ Highest volume of fire, but can permanently damage the machine gun

23. Questions?