Rifle Scopes Drop table for my .308 help

[K_4c]

Can someone please verify if my calculations are in the ballpark....

Here are the variables:

Rifle: REPR 20" 1:10 RH twist
Optic: SH IOR 3x18 MIL/MIL
Ammo: Hornady 168 gr AMAX, BC .475, Muzzle velocity 2600 (out of a 20" barrel).

here's the data/dope I'm getting off jbmballistics.com with a 100 meter zero with a 80 degree day and 62.0% humidity.

Range: Mil correction:
200 0.0
250 .2
300 .2
350 .35/.4
400 .6/.7
450 1.
500 1.5
550 2.1
600 2.8
650 3.6
700 4.5
750 5.5
800 6.7
850 8.0
900 9.5
950 11.3
1000 13.2

I got these figures by finding the bullet drop divided by 3.6 divided by 10. Example: At 1000 m the bullet drops -476". I divide 476 by 3.6 which gives me 132.2. I then divide 132.2 by 10 to give me a 13.2 mil hold.... did I screw up or does this look correct? Just looking to get close with these corrections.....

 

[sobrbiker883]

Re: Drop table for my .308 help

Why not just run jbm with the output in mils?

 

[K_4c]

Re: Drop table for my .308 help

did I miss that function??? fuck me...

I'll take another look.

thanks for the input bud,

Kinnamon

 

[K_4c]

Re: Drop table for my .308 help

yep...found it.

 

[sobrbiker883]

Re: Drop table for my .308 help

Your table looks pretty close off the top of my head.

I prefer the "trajectory card" with output in mil and moa (makes it really easy to give others ballpark dope or if I'm running a different scope for some reason.

 

[K_4c]

Re: Drop table for my .308 help

Does this look better?

Trajectory
Input Data
Manufacturer: Hornady Description: A-Max®
Caliber: 0.308 in Weight: 168.0 gr
Ballistic Coefficient: 0.475 G1

Muzzle Velocity: 2600.0 ft/s Distance to Chronograph: 10.0 ft

Sight Height: 1.50 in Sight Offset: 0.00 in
Zero Height: 0.00 in Zero Offset: 0.00 in
Windage: 0.000 mil Elevation: 0.000 mil
Line Of Sight Angle: 0.0 deg Cant Angle: 0.0 deg

Wind Speed: 5.0 mph Wind Angle: 90.0 deg
Target Speed: 5.0 mph Target Angle: 90.0 deg

Temperature: 80.0 °F Pressure: 29.92 in Hg
Humidity: 62.0 % Altitude: 1200.0 ft

Vital Zone Radius: 5.0 in

Std. Atmosphere at Altitude: No Pressure is Corrected: Yes
Zero at Max. Point Blank Range: Yes Target Relative Drops: Yes
Mark Sound Barrier Crossing: Yes Include Extra Rows: Yes
Column 1 Units: 1.00 mil Column 2 Units: 1.00 mil
Round Output to Whole Numbers: No
Output Data
Elevation: 8.059 MOA Windage: -0.965 MOA

Atmospheric Density: 0.06977 lb/ft³ Speed of Sound: 1138.9 ft/s

Maximum PBR: 292 m Maximum PBR Zero: 248 m
Range of Maximum Height: 136 m Energy at Maximum PBR: 1613.7 ft•lbs

Sectional Density: 0.253 lb/in²
Calculated Table
Range Drop Drop Windage Windage Velocity Mach Energy Time Lead Lead
(m) (mil) (mil) (mil) (mil) (ft/s) (none) (ft•lbs) (s) (mil) (mil)
0 *** *** *** *** 2605.8 2.288 2532.6 0.000 *** ***
25 0.6 0.6 -0.3 -0.3 2558.2 2.246 2440.9 0.032 2.8 2.8
50 1.2 1.2 -0.2 -0.2 2511.1 2.205 2351.9 0.064 2.9 2.9
75 1.2 1.2 -0.2 -0.2 2464.5 2.164 2265.3 0.097 2.9 2.9
100 1.1 1.1 -0.2 -0.2 2418.4 2.124 2181.3 0.131 2.9 2.9
125 1.0 1.0 -0.1 -0.1 2372.7 2.083 2099.8 0.165 2.9 2.9
150 0.8 0.8 -0.1 -0.1 2327.6 2.044 2020.6 0.200 3.0 3.0
175 0.6 0.6 -0.1 -0.1 2282.9 2.005 1943.7 0.235 3.0 3.0
200 0.4 0.4 -0.1 -0.1 2238.6 1.966 1869.1 0.272 3.0 3.0
225 0.2 0.2 -0.0 -0.0 2194.9 1.927 1796.8 0.309 3.1 3.1
248 -0.0 -0.0 0.0 0.0 2155.1 1.892 1732.2 0.343 3.1 3.1
250 -0.0 -0.0 0.0 0.0 2151.6 1.889 1726.7 0.346 3.1 3.1
275 -0.3 -0.3 0.0 0.0 2108.8 1.852 1658.7 0.385 3.1 3.1
292 -0.4 -0.4 0.1 0.1 2080.0 1.826 1613.7 0.412 3.2 3.2
300 -0.5 -0.5 0.1 0.1 2066.6 1.815 1592.8 0.424 3.2 3.2
325 -0.8 -0.8 0.1 0.1 2024.8 1.778 1529.1 0.464 3.2 3.2
350 -1.0 -1.0 0.1 0.1 1983.5 1.742 1467.4 0.505 3.2 3.2
375 -1.3 -1.3 0.2 0.2 1942.8 1.706 1407.8 0.547 3.3 3.3
400 -1.6 -1.6 0.2 0.2 1902.6 1.671 1350.2 0.590 3.3 3.3
425 -1.9 -1.9 0.2 0.2 1863.0 1.636 1294.5 0.633 3.3 3.3
450 -2.2 -2.2 0.3 0.3 1823.9 1.602 1240.8 0.678 3.4 3.4
475 -2.5 -2.5 0.3 0.3 1785.5 1.568 1189.0 0.723 3.4 3.4
500 -2.8 -2.8 0.3 0.3 1747.6 1.535 1139.1 0.770 3.4 3.4
525 -3.2 -3.2 0.4 0.4 1710.4 1.502 1091.1 0.817 3.5 3.5
550 -3.5 -3.5 0.4 0.4 1673.8 1.470 1044.9 0.866 3.5 3.5
575 -3.9 -3.9 0.5 0.5 1637.9 1.438 1000.6 0.915 3.6 3.6
600 -4.2 -4.2 0.5 0.5 1602.7 1.407 958.0 0.966 3.6 3.6
625 -4.6 -4.6 0.5 0.5 1568.2 1.377 917.2 1.018 3.6 3.6
650 -5.0 -5.0 0.6 0.6 1534.5 1.347 878.2 1.070 3.7 3.7
675 -5.4 -5.4 0.6 0.6 1501.5 1.318 840.9 1.124 3.7 3.7
700 -5.8 -5.8 0.7 0.7 1469.4 1.290 805.3 1.180 3.8 3.8
725 -6.3 -6.3 0.7 0.7 1438.1 1.263 771.4 1.236 3.8 3.8
750 -6.7 -6.7 0.8 0.8 1407.7 1.236 739.1 1.294 3.9 3.9
775 -7.2 -7.2 0.8 0.8 1378.2 1.210 708.4 1.353 3.9 3.9
800 -7.6 -7.6 0.9 0.9 1349.7 1.185 679.4 1.413 3.9 3.9
825 -8.1 -8.1 0.9 0.9 1322.1 1.161 652.0 1.474 4.0 4.0
850 -8.6 -8.6 0.9 0.9 1295.6 1.138 626.0 1.537 4.0 4.0
875 -9.2 -9.2 1.0 1.0 1270.1 1.115 601.7 1.601 4.1 4.1
900 -9.7 -9.7 1.0 1.0 1245.7 1.094 578.8 1.666 4.1 4.1
925 -10.2 -10.2 1.1 1.1 1222.5 1.073 557.4 1.733 4.2 4.2
950 -10.8 -10.8 1.1 1.1 1200.4 1.054 537.4 1.800 4.2 4.2
975 -11.4 -11.4 1.2 1.2 1179.5 1.036 518.9 1.869 4.3 4.3
1000 -12.0 -12.0 1.2 1.2 1159.7 1.018 501.6 1.940 4.3 4.3

24/04/10 01:59, JBM/jbmtraj-5.0.cgi

 

[sobrbiker883]

Re: Drop table for my .308 help

The second is in yards and the first is in meters correct? that would explain why the 1000 is different by 1.2mil......if not something's different between the two.

 

[K_4c]

Re: Drop table for my .308 help

nope they're both in meters.... shits getting a little old. I'll sit down later today and mess around with it.

 

[Wild_Man]

Re: Drop table for my .308 help

Looks like a 200m zero on the first one and a 248m zero on the second.

 

[jdgray]

Re: Drop table for my .308 help

Man, I hope you didn't type all that in!

 

[K_4c]

Re: Drop table for my .308 help

no... haha... copy and paste forsure.

 

[sobrbiker883]

Re: Drop table for my .308 help

When you try it again, just use the Trajectory u card link, and put in that you want for the output ranges. If you don't have lo/hi chrono tempd data put one temp in for both.

You do have 2 different zeroes on the two you posted.

 

[K_4c]

Re: Drop table for my .308 help

Got it! thanks sobrbiker.

Trajectory μCard
REPR DOPE
Range Drop Wind
(m) (mil) (mil) (mil) (mil)
100 0.0 0.0 0.2 0.2
200 -0.7 -0.7 0.5 0.5
250 -1.1 -1.1 0.6 0.6
300 -1.6 -1.6 0.7 0.7
325 -1.9 -1.9 0.8 0.8
350 -2.1 -2.1 0.9 0.9
375 -2.4 -2.4 0.9 0.9
400 -2.7 -2.7 1.0 1.0
425 -3.0 -3.0 1.1 1.1
450 -3.3 -3.3 1.2 1.2
475 -3.6 -3.6 1.2 1.2
500 -3.9 -3.9 1.3 1.3
525 -4.2 -4.2 1.4 1.4
550 -4.6 -4.6 1.5 1.5
575 -4.9 -4.9 1.6 1.6
600 -5.3 -5.3 1.6 1.6
625 -5.7 -5.7 1.7 1.7
650 -6.1 -6.1 1.8 1.8
675 -6.5 -6.5 1.9 1.9
700 -6.9 -6.9 2.0 2.0
725 -7.4 -7.4 2.1 2.1
750 -7.8 -7.8 2.2 2.2
775 -8.3 -8.3 2.3 2.3
800 -8.8 -8.8 2.4 2.4
825 -9.3 -9.3 2.5 2.5
850 -9.8 -9.8 2.6 2.6
875 -10.3 -10.3 2.7 2.7
900 -10.9 -10.9 2.8 2.8
925 -11.4 -11.4 2.9 2.9
950 -12.0 -12.0 3.0 3.0
975 -12.6 -12.6 3.1 3.1
1000 -13.2 -13.2 3.2 3.2