Range Report JBM Clculator Bug?

[Buckoman]

So I assume its me so I'm hoping someone can/will explain this to me. When i plug in my crony data to JBM it won't out put the MOA drop in a way that makes sense or that I can correlate with my real DOPE data. It seems that it wants to calculate trajectory in reference to line of sight. Worse it wont zero the round at the input zero range of 100 yds.

My live DOPE is:
yds
100: zero
200: 2MOA
300: 4MOA
400: 9MOA
500: 12MOA
600: 17.5MOA

JBM gives me:
+4.7 MOA at 100 yards.

2500fps 175 SMK

 

[goober]

Re: JBM Clculator Bug?



I imagine its quite simple unless I have misunderstood whats written after a few drinks but -your wrong

Trajectory
Input Data
Ballistic Coefficient: 0.475 G1 Caliber: 0.308 in
Bullet Weight: 175.0 gr
Muzzle Velocity: 2850.0 ft/s Distance to Chronograph: 10.0 ft
Sight Height: 2.60 in Sight Offset: 0.00 in
Zero Height: 0.00 in Zero Offset: 0.00 in
Windage: 0.000 MOA Elevation: 0.000 MOA
Line Of Sight Angle: 0.0 deg Cant Angle: 0.0 deg
Wind Speed: 10.0 mph Wind Angle: 90.0 deg
Target Speed: 10.0 mph Target Angle: 90.0 deg
Target Height: 12.0 in
Temperature: 59.0 °F Pressure: 29.92 in Hg
Humidity: 0.0 % Altitude: 100.0 ft
Vital Zone Radius: 5.0 in
Std. Atmosphere at Altitude: No Pressure is Corrected: Yes
Zero at Max. Point Blank Range: No Target Relative Drops: Yes
Mark Sound Barrier Crossing: No Include Extra Rows: No
Column 1 Units: 1.00 in Column 2 Units: 1.00 MOA
Round Output to Whole Numbers: No
Output Data
Elevation: 4.615 MOA Windage: 0.000 MOA
Atmospheric Density: 0.07619 lb/ft³ Speed of Sound: 1116.4 ft/s
Maximum PBR: 356 yd Maximum PBR Zero: 304 yd
Range of Maximum Height: 174 yd Energy at Maximum PBR: 1871.5 ft•lbs
Sectional Density: 0.264 lb/in²
Calculated Table
Range Drop Drop Windage Windage Velocity Mach Energy Time Lead Lead
(yd) (in) (MOA) (in) (MOA) (ft/s) (none) (ft•lbs) (s) (in) (MOA)
0 -2.6 *** 0.0 *** 2856.7 2.559 3170.5 0.000 0.0 ***
100 -0.0 -0.0 0.7 0.6 2660.4 2.383 2749.9 0.109 19.2 18.3
200 -2.3 -1.1 2.8 1.3 2472.6 2.215 2375.2 0.226 39.7 19.0
300 -10.3 -3.3 6.5 2.1 2292.4 2.053 2041.7 0.352 61.9 19.7
400 -25.0 -6.0 11.9 2.9 2119.7 1.899 1745.7 0.488 85.9 20.5
500 -47.4 -9.0 19.4 3.7 1954.7 1.751 1484.5 0.635 111.8 21.4
600 -78.9 -12.6 29.1 4.6 1797.9 1.610 1255.9 0.795 140.0 22.3
700 -121.2 -16.5 41.3 5.6 1650.3 1.478 1058.1 0.970 170.6 23.3
800 -176.3 -21.0 56.2 6.7 1513.2 1.355 889.6 1.159 204.1 24.4
900 -246.6 -26.2 74.2 7.9 1388.2 1.243 748.7 1.367 240.5 25.5
1000 -335.0 -32.0 95.4 9.1 1277.3 1.144 633.9 1.592 280.2 26.8
06/05/11 04:49, JBM/jbmtraj-5.1.cgi

Click here to report an error.

 

[mouse07410]

Re: JBM Clculator Bug?

I think it's fairly simple. Down at the botton of the JBM Trajectory screen/page there's a set of check-boxes.

Make sure you checked the box labeled <span style="font-style: italic">Elevation Correction for Zero Range</span>.

 

[Buckoman]

Re: JBM Clculator Bug?

see I told ya'll I figured it was me. Lemme play with it some more. Thanks for the help gentlemen. I'll keep ya posted if I'm still stuck on stupid.

 

[Buckoman]

Re: JBM Clculator Bug?

Now I figured it out. "I checked zero at max point blank range" and that offsets the DOPE according to PBZ. DUH!!!!! Thanks again fellas