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Ballistics and Zeroing
Ballistics
Definition:
Everything that happens to the projectile from the
time the primer is struck by the firing pin until the
projectile comes to a complete stop.
There are three ballistic phases:
1. Internal
2. External
3. Terminal
Of the three phases, we will discuss one;
External ballistics.
A.
B.
C.
D.
E.
Gravity and air resistance have a constant and continuous effect on a
bullet passing through the air.
This constant effect causes the flight (trajectory) of the bullet to be a
definitive and uniform arc.
A common cylindrical bullet has no loft capabilities, as does an airplane
wing.
The sole purpose of the spin that is imparted upon a bullet is to keep the
projectile from tumbling end over end.
A bullet fired from a true horizontal barrel begins to slow down and fall
towards the earth immediately upon leaving the muzzle of the weapon.
Two basic concepts that are common to most of us
will help you to visualize how a bullet is sent
through the air when leaving a rifle barrel.
A. The flight of a football.
B. A common children’s top.
Bullet Trajectory
A bullet flying through the air is acted upon
primarily by two forces, which change the direction
and velocity of its motion.
These two forces are:
A. Gravity
-Causes the bullet to fall towards the earth
B. Air Resistance
-Causes the bullet to slow down
-Causes the bullet to fly erratically and tumble
Bullet Trajectory cont.
We try and counter these forces on the bullet in
three basic manners.
• (1) Increase the angle of departure (elevating
the muzzle) to counter the effects of gravity and
allow the bullet to reach further distances.
• (2) Impart spin and (3) high velocities on the
bullet to counter air resistance and allow the bullet
to fly in an nose forward manner at far distances.
Parts of a Trajectory
Line of Sight:
This is what the shooter sees behind the sights
and can be illustrated by drawing an imaginary
line from your eye through the rear and front
sights out to infinity. This is how you aim.
Line of Sight
Line of Bore
This is an imaginary line that is drawn from the
chamber where the bullet lies through the barrel out
to infinity. It is also the path a bullet would take if
gravity and wind resistance weren’t a factor. It would
in effect be a laser.
Line of Bore
Trajectory or Path of Bullet
The path of flight that the bullet will take when it
is fired from the rifle. The following is an example
of what happens when a bullet leaves the bore of
a rifle in which the barrel is horizontal to the
ground and the line of sight is parallel to the line
of bore.
Path of Bullet
What has to change to be able to engage this target?
300m
PathPath
of Bullet
of Bullet
300m
•Increasing the angle of departure will allow the bullet to impact the
target at the given distance.
•This causes us to lose sight of the target.
•To be able to aim at the target, the sights must be adjusted.
Parallel Sight and Bore relationship
Lowering the front sight post
Re-acquire proper SIGHT ALIGNMENT
and you have elevated the line of departure.
Parallel Sight and Bore relationship
Raise the rear sight
Re-acquire proper SIGHT ALIGNMENT,
and you have elevated the line of departure.
The diagram below shows us how the Army is able to zero at
25m and still be center of mass on a 300m target.
Line of Sight
25 meters
150 meters
300 meters
The distance the muzzle is raised may not be noticeable with the naked
eye, but even at 25m, the muzzle is slightly elevated.
Minute of Angle (MOA)
 Unit of measure
 1 minute of angle= 1 inch per 100 yards
 Sights and scopes move in Minutes of Angle
 Wind is estimated in Minutes of Angle
1”
2”
3”
4”
1 moa
100
200
300
400
Minute of Angle (MOA) worksheet
1) 6” @ 600m= ?MOA
6”/ (6)00m=1 MOA
2) 3 MOA @ 200m= ?inch
3 x (2)00= 6 inches
3) 6” @ 400m= ?MOA
6”/4= 1.5 MOA
4) 4 MOA @300m= ?inch
4 x (3)00= 12 inches
5) 20” @ 500m= ?MOA
20”/ 5= 4 MOA
6) 5 MOA @ 300m= ?inch
5 x 3= 15 inches
Value of clicks in MOA for iron sights:
WEAPON
TYPE
ELEVATION
KNOB
WINGDAGE
KNOB
FRONT
SIGHT POST
M16A2
1
1/2
1 1/4
M16A4
1/2
1/2
1 1/4
M4
1 1/4
3/4
1 1/2
300m
40”
1.
a.
b.
c.
d.
Elevation adjustment?
Need to come down 12”
12”/3(00)m= 4= 4 MOA
1 click on front sight= 1 ¼ MOA
4 MOA= about 3 clicks on front sight
2.
a.
b.
c.
d.
Windage adjustment?
Need to come left 21”
21”/3(00)m= 7 MOA
1 click of windage= ½ MOA
7 MOA = 14 clicks of windage
IMPACT
19”
Zeroing: What is the definition?
The average answer is:
“Adjusting the sights so that the bullets impact where we are
aiming.”
FM 3-22.9 states: The purpose of battlesight zeroing is to align
the sights with the weapon’s barrel given standard issue
ammunition.
Both answers are correct.
Zeroing continued
The Army has developed methods for engaging
targets based on the following two scenarios:
1)Unknown distance=Battle Sight Zero (BSZ)
1)Known distance=Bullet Drop Compensating (BDC)
Battle Sight Zero
 A Battle Sight Zero allows you to aim center mass on a target and
achieve a hit from zero to 300m. A correctly zeroed rifle will impact
within 10 inches of your point of aim.
Trajectory
Line of Sight
32m
150m
10 inches
300m
Battle Sight Zero
 350m = 10” below point of aim
 400m = 20 inches below point of aim
Trajectory
Line of Sight
300m
350m
400m
10 inches
Bullet Drop Compensating
 The elevation wheel on the rear sight is known as a Bullet Drop Compensator.
 The numbers on the wheel represent distances in meters.
 How it works:
 Bottom out the rear sight and click up to 8/3 or 6/3. The BDC is now set for
300 meters.
 Clicking up to 4,5,6,7 or 8 adjusts the trajectory of the round to engage
targets at the corresponding distance (i.e. 4=400m, 5=500m).
 One full revolution up from 300 correlates to the number on the left side of
3. For a 6/3 BDC the elevation would be set at 600 meters. This is why it is
essential that the elevation wheel is bottomed out and then clicked up to
6/3 or 8/3 before zeroing.
 Elevation changes at 25 meters are made with the front sight post so that the
Bullet Drop Compensator can be used to engage targets beyond 300 meters.
Sight is bottomed out therefore
the right number is used (3),
which indicates 300 meters.
Gap is noticeable, the sight is up
one “revolution” from (3) so the
left number is used (6), which
now indicates 600 meters.
Representation of M16 Bullet Path
25 m
7”-10”
150m
300m
ZEROING AT 25 METERS
M16A2/A3
Up 1 click
M16A4
Up 2 clicks
350m
M16 Rear Sights
M16A2/A3
M16A4
The difference can be seen in the
thread pitch between a rear sight on a
fixed carrying handle and that of a
detachable. This is why you have to
come up only one click on the
M16A2/A3 and two clicks on the
M16A4.
(Reference Army TM9-1005-319-10 Pg.
0011 00-7 #4)
Difference in Thread Pitch
Representation of M4 Bullet Path
25m
150m
300m
350m
M4 Zeroing:The M4 and M16A4 share the same carrying handle,
however the M4’s shorter barrel produces less muzzle velocity. The
line of sight and path of the bullet cross at 25m AND at 300m.
Pre-range departure/post weapons draw checks
BDC is bottomed out
and on
300 meter setting
Small rear sight aperture is
up and “windage” index
lines are centered.
Front sight post is not
bent or
damaged and the
base of the sight post
is flush with the front
sight base.
Which is CENTER MASS?
Center Mass
Including head
Center Mass
NOT Including the head
Modified zeroing target
Emphasize zeroing in the lower half of the 4 cm circle.
This will ensure a higher probability of hits from 150-250 meters.
 If possible, 5 shot groups are recommended
 Makes triangulation more accurate
3 Shot vs 5 Shot
INTRODUCTION TO THE TA01NSN
ACOG
NSN 1240-01-412-6608
CHARACTERISTICS of TA01NSN
 4x magnification.
 32mm objective lens.
 Waterproof to depth of 66 feet.
 Eye relief 1.5 inches.
 Field of view at 100 yds. = 36.8 feet
 Adjustments= 1/3 MOA per click (clicks/in @
100 m.) = 3
ZEROING the TA01NSN
Two methods:
1. 100 meter zero (most accurate)
-
Use center cross hair
Point of aim/ point of impact
2. 25 meter combat zero
-
Use 300m reticle
Point of aim/ point of impact
Reticle/silhouette relationship @ 100 meters
100m
200m
300m
INTRODUCTION TO THE
TA31F ACOG SCOPE
NSN 1240-01-514-8428
CHARACTERISTICS OF TA31F
 4x magnification.
 32mm objective lens.
 Waterproof to depth of 66 feet.
 Eye relief 1.5 inches.
 Field of view at 100 yds. = 36.8 feet
 Adjustment= 1/3 MOA per click(3 clicks = 1
inch @ 100m)
100m
Aiming points for:
200m
300m
For rapid engagement of targets less than
300m use this hold
ZEROING the TA31F
Two methods:
1. 100 meter zero (most accurate)
- Use point of red chevron
- Point of aim/ point of impact
2. 25 meter combat zero
- Use top of 300m post (underneath chevron)
- Point of aim/ point of impact
ZEROING the TA31F cont.
100 meter
POA/POI
3 clicks = 1 MOA
For both elevation
and windage
ZEROING the TA31F cont.
25 meter- POA/POI
Use top of 300m post
12 clicks = 1”
For both
9 clicks = 1”
For and
both
elevation
elevation and
windage
windage
If red chevron is too bright- cover fiber optic with tape.
What are your questions?

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