Make your own free website on Tripod.com
TRAJECTORY TABLE, FEDERAL MATCH .308 CAL.168-Gr. BOATTAIL HOLLOWPOINT

TRAJECTORY TABLE, FEDERAL MATCH .308 CAL.168-Gr. BOATTAIL HOLLOWPOINT
Trajectory by Yards, Expressed in Inches

Zero Range
100
200
300
400
500
600
700
800
900
1000
100 Yards
Zero
-4.5
-15.9
-35.5
-64.6
-105
-159
-228
-315
-421
300 Yards
+5.3
+6.1
zero
-14.3
-38.1
-73.2
-121
-185
-267
-369
400 Yards
+8.9
+13.3
+10.8
Zero
-20.1
-57.6
-96.3
-157
-235
-333
500 Yards
+13.0
+21.5
+23.1
+16.5
Zero
-27.0
-67.6
-124
-198
-292
600 Yards
+17.5
+30.5
+36.6
+34.5
+22.9
zero
-36.1
-87.8
-157
-247
700 Yards
+22.6
+40.7
+51.9
+54.9
+48.4
+30.6
Zero
-47.0
-112
-196
800 Yards
+28.4
+51.4
+69.3
+78.1
+77.4
+65.4
+40.2
Zero
-59.4
-139
900 Yards
+35.0
+65.5
+89.1
+105
+110
+105
+86.4
+52.2
Zero
-72.4
1000 Yards
+42.2
+80.0
+111
+133
+147
+149
+137
+110
+65.2
Zero

Table Two contains basic velocity and energy data.

TABLE TWO

FEDERAL .308 168-Gr. BT HP Match, Velocity in Ft-per-sec., Energy in Ft-Lbs.

Muzzle
100
200
300
400
500
600
700
800
900
1000
VELOCITY
2600
2420
2240
2070
1910
1760
1610
1480
1360
1260
1170
ENERGY 2520 2180 1870 1600 1355 1150 970 815 690 590 510

Moving Target Data and Compensation

     Normally it's much better to wait and engage your target when he pauses momentarily rather than attempt a moving target shot. But a moving target may be the only shot you've got.

     All the data published in Table Three reflects a target moving 90 degrees to the path of your bullet, that is, moving directly right or left, which is FULL VALUE. Should the target move oblique right or left, whether toward or away from you, use ONE HALF the value since in relative terms he's crossing your front at half the speed. And when he's heading directly toward you or away from you, there's NO VALUE and no movement compensation or leads at all. Aim dead-on.

TABLE THREE

MOVING TARGET LEADS, .308 Federal Match 168 Gr. BTHP

Distance in Yards
Tgt. Speed
100
200
300
400
500
600
700
800
900
1000
Walk 3 MPH
7"
13”
21"
29"
37"
46”
56"
68"
80”
93"
Trot 6 MPH
13”
26"
42”
57”
74”
92”
113"
135"
158"
185”
Dash 10 MPH
21"
44"
68"
95"
122”
154”
187"
224"
264”
306”

     Must you actually carry all this data in your head? No. I memorize just the 3 MPH leads, then double them for a trotting target and triple them if it's at a dead run. And I can mentally cut in half any one of these if the target's moving obliquely.

     The easiest way to remember the 3 MPH moving target leads is to COUNT IN SEVENS -- 7, 14, 21, 28, 35, 42 and you'll have the correct walking leads almost perfectly for 100, 200, 300, 400, 500 and even 600 yards.

Crosswind Data

     The best reaction to a stiff crosswind is to shift your location so you're either perfectly upwind or downwind from your target and thereby eliminate the effect of wind altogether.

     When relocating is physically or tactically unfeasible, the Wind Data in Table Four allows great accuracy when properly applied.

     And don't forget that unlike a moving target, an oblique wind is NOT 1/2 value but 3/4 value since a bullet is very sensitive to a crosswind.

TABLE FOUR

WIND DRIFT DATA for Federal .308, 168 Gr. BTHP Match

Effects of a Crosswind 90 Degrees to Bullet Path

100
200
300
400
500
600
700
800
900
1000
5 mph
0.4”
1.5”
3.7"
6.8”
11.1”
16.1”
23.5”
32.0”
42.1”
53.8”
10 mph
0.8”
3.1"
7.4”
13.6"
22.2”
33.3”
47.1”
64.1”
84.2”
107”
15 mph
1.2"
4.6”
11.1"
20.4”
33.3”
49.9”
70.6"
96.1"
126”
161”
20 mph
1.6"
6.2”
14.8"
27.2”
44.4”
66.6”
94.2"
128"
168”
215"
30 mph
2.4"
9.3”
22.2"
40.8”
66.6”
99.9”
141"
192"
253”
322”

Up/Down Shooting Compensation

     While the book explains this phenomenon in depth, just let it be said here that up/down shooting requires aiming LOW for compensation. Despite it not seeming logical, this is equally true whether your target is downhill or uphill; always compensate by

AIMING LOW

     Keep in mind how quickly angles increase as a suspect's position gets higher above street-level -- by the time he's about 4 - 5 stories or higher, and you’re across an average downtown street, he's probably already 40 degrees UP. The Austin 'Texas Tower' gunman, Charles Whitman, fired from a 28-story perch about 50 degrees UP from most-lawmen, who typically returned fire from cover 300 yards away. This means their uncompensated shots probably hit about ten inches high and helps explain why it took so long to neutralize him.

     We computed this data for UP/Down angles at 5 through 60 degrees in Table Five, just so you could get a better feel for the effect. (Sixty degrees is the angle at which the greatest compensation is required.)

TABLE FIVE

Federal .308 Match, 168 Gr. BTHP Up/Down Compensation

Distance (Yards)
Degree Slope
100
200
300
400
500
600
700
800
900
1000
5 Degrees
.01”
.04”
.10"
.20”
.33”
.51"
.74"
1.0”
1.4”
1.8”
10 Degrees
.04"
.16"
.40”
.75"
1.2"
1.9”
2.7"
3.9”
5.2"
6.9”
15 Degrees
.09"
.38"
.91”
1.7”
2.8"
4.3”
6.3"
8.7"
12”
16"
20 Degrees
.16”
.67"
1.6"
3.0"
5.0"
7.7”
11"
15”
21”
28”
25 Degrees
.25"
1.0"
2.5"
4.7"
7.8"
12”
17"
24”
33”
43”
30 Degrees
.30"
1.5”
3.5"
6.7"
11"
17"
25"
34"
47”
62"
35 Degrees
.48”
2.0"
4.8"
9.0"
15"
23”
33"
47”
63”
84"
40 Degrees
.62”
2.6"
6.3”
12”
19"
30"
43"
60”
82”
108”
45 Degrees
.70"
3.3"
7.8”
15"
24”
37"
54"
75"
102”
135"
50 Degrees
.90"
4.0”
9.6"
18”
30"
46"
66"
92"
125”
165"
55 Degrees
1.1"
4.8”
11"
21”
35"
54"
79”
110"
149”
197”
60 Degrees
1.3”
5.6"
13"
25"
41"
64”
92”
128”
174”
232”

REMEMBER: Always compensate by aiming LOW!

     To keep from dazzling you with too much complicated up/down information, I've included "Simplified UP/DOWN Data' (Table Six) which shows the compensation needed at 100 yards for 30-, 45- and 60-degree up/down targets. You can see that there’s little com¬ pensation required at such short range until the angle approaches 60 degrees, and even then you need only aim 1.3 inches LOW to be perfectly on-target.

TABLE SIX

SIMPLIFIED UP/DOWN DATA
100-Yard Distance

Angle
Compensation
30 Degrees
0.3”
45 Degrees
0.7”
60 Degrees*
1.3"

* Maximum effect

     So that you can see how to translate this up/down data into 1/4 Minute of Angle scope adjustments, we've included Table Seven, which shows these computations for a 45 Degree Slope.

TABLE SEVEN

Federal .308 Match, 168 Gr. BTHP

Minutes of Angle Up/Down Compensation, 45 Degrees
Yards
Compensation
MOAs
1/4 MOA Clicks
100
0.7”
0.70
3 (0.74 MOA)
200
3.3”
1.65
7 (1.75 MOA)
300
7.8”
2.60
10 (2.50 MOA)
400
15.0”
3.75
15 (3.75 MOA)
500
24.0”
4.80
19 (4.75 MOA)
600
37.0”
6.10
24 (6.00 MOA)
700
54.0”
7.70
31 (7.75 MOA)
800
75.0”
9.37
37 (9.25 MOA)
900
102”
11.30
45 (11.25 MOA)
1000
135”
13.50
54 (13-50 MOA)

REMEMBER: Always compensate by aiming LOW!

Comeups

     The idea of Comeups is to KNOW the exact Minutes of Angle a rifleman needs to raise his sights in order to hit dead-on, when changing from one distance to another, at 100-yard intervals.

     A scope-equipped police rifleman uses Comeups either with target knobs or even just an elevation ring, to count off 1/4 MOA clicks as he cranks to another elevation. Comeups are calculated for a specific round -- based on bullet weight, velocity and resulting trajectory. The ones listed in this table exactly fit the Federal .308 Match trajectory and would not apply perfectly even to the very similar 7.62mm military Match bullet.

     Most modern, quality riflescopes adjust elevation with 1/4 Minute of Angle clicks, which means you must click-off four increments to equal one Minute of Angle. If you have any doubt about your scope’s elevation increments, check with an armorer or the manufacturer.

     Also understand that the Comeups shown in Table Eight work REGARDLESS of your zero range. In essence, they tell you how much to go up or down from one zero so you'll be zeroed at the next range. There may be tiny variations between these calculations and your own rifle's performance, so testfire and modify them for the most precise results.

TABLE EIGHT

COMEUPS

Federal .308 Match, 168-gr. BT HP

Yards
MOAs
1/4 MOA Clicks
100 to 200
2.25
Nine
200 to 300
3.00
Twelve
300 to 400
3.50
Fourteen
400 to 500
4.00
Sixteen
500 to 600
4.50
Eighteen
600 to 700
5.00
Twenty
700 to 800
5.75
Twenty-Three
800 to 900
6.50
Twenty-Six
900 to 1000
7.25
Twenty-Nine

<