Rifle Scopes Can you help make sure this is right

[jmyner99er]

Hi guys, I have a few questions on the JBM calculator, and Im wondering if you could double check my numbers and help me figure out the range cards. I feel the simplified trajectory card is accurate except for the elevation differences; my question is on the atmospheric differences when he sighted it in versus where my dad will be hunting. (And figuring out the range cards)

In the past, he would just aim high, now that we figured out his scope clicks he is excited to see a big buck out 500+ yards, so bullet drop, elevation/windage clicks are important.

Here is some info.
Chamber; 300 win mag (.308)
Reloaded (consistent) IMR 4831 @ 74gr
Bullet; Nosler 165 Ballistic tip, bc .410, sd .248
Optics; Swarovski Habicht 3-12x50 .36in/100yards

Sighted in at 300ft elevation @ 70 degrees F
Hunting at 7600 ft elevation (high 59 degrees, low 25 degrees)

Sighting in at 100yrds three inches high, put him ¾” high at 300yrds

On the range cards, (Trajectory Card, Ucard, and Ucard Constant Drop) Im having trouble, getting results, and interpreting them. (Drop units and windage units, not sure what I need there?)

I will add the simplified trajectory chart that I came up with.



Trajectory (Simplified)
Input Data
Manufacturer: Nosler Description: Ballistic Tip™
Caliber: 0.308 in Weight: 165.0 gr
Ballistic Coefficient: 0.475 G1

Muzzle Velocity: 3100.0 ft/s

Sight Height: 1.65 in Line Of Sight Angle: 0.0 deg
Cant Angle: 0.0 deg

Wind Speed: 10.0 mph Target Speed: 5.0 mph

Temperature: 59.0 °F Pressure: 29.92 in Hg
Humidity: 40.0 % Altitude: 7600.0 ft

Std. Atmosphere at Altitude: Yes Pressure is Corrected: No
Zero at Max. Point Blank Range: No Target Relative Drops: No
Round Output to Whole Numbers: Yes
Output Data
Elevation: 1.840 mil Windage: 0.000 mil

Atmospheric Density: 0.06086 lb/ft³ Speed of Sound: 1086.9 ft/s

Maximum PBR: 384 yd Maximum PBR Zero: 326 yd
Range of Maximum Height: 180 yd Energy at Maximum PBR: 2286.4 ft•lbs

Sectional Density: 0.248 lb/in²

Column 2 Drop/Windage Units: 1/10 mil Clicks
Calculated Table
Range Drop Drop Windage Windage Velocity Mach Energy Time Lead Lead
(yd) (in) (Clicks) (in) (Clicks) (ft/s) (none) (ft•lbs) (s) (in) (Clicks)
100 3 9 0 1 2934.8 2.700 3155.0 0.099 9 24
150 4 7 1 2 2854.6 2.626 2985.0 0.151 13 25
200 4 5 2 3 2775.9 2.554 2822.7 0.205 18 25
250 2 3 3 3 2698.7 2.483 2667.8 0.259 23 25
300 -0 -0 4 4 2622.8 2.413 2519.9 0.316 28 26
350 -4 -3 6 5 2548.3 2.345 2378.8 0.374 33 26
400 -9 -6 8 6 2475.0 2.277 2243.9 0.434 38 26
450 -15 -9 10 6 2403.0 2.211 2115.2 0.495 44 27
500 -23 -13 13 7 2332.1 2.146 1992.3 0.558 49 27
550 -33 -17 16 8 2262.5 2.082 1875.1 0.624 55 28
600 -44 -21 19 9 2194.0 2.019 1763.2 0.691 61 28
650 -57 -25 23 10 2126.6 1.957 1656.6 0.760 67 29
700 -73 -29 27 11 2060.4 1.896 1555.1 0.832 73 29
750 -90 -33 32 12 1995.4 1.836 1458.5 0.906 80 30

On the data output, what does this mean: Elevation: 1.840 mil (and why is the windage at 0.00mil?)

Thanks

 

[ChadTRG42]

Re: Can you help make sure this is right

99er,

JBM can be over whelming if you mess up one field. Take a look at this website. It is a little more simplified. Just enter in your info like you have, and it will be easier to understand. You scope is in mils (.1 mil per "click")

 

[jmyner99er]

Re: Can you help make sure this is right

Thanks for the reply! I checked out the site, and ran the numbers, but it doesnt give me bullet drop in inches, and how many clicks to compensate.

When you say "You scope is in mils (.1 mil per "click")" would that be for the range cards on the JBM site?

 

[Lindy]

Re: Can you help make sure this is right

I recommend that you stop thinking of clicks.

Scopes commonly adjust in whole or fractions of three units of angular measurement:

1. Minutes of Angle or MOA.
2. Milliradians, sometimes referred to as "mils".
3. Inches Per Hundred Yards or IPHY.

Many ballistic programs can be set to output data in any of those units.

Think of your dope in whichever of those units is appropriate to your scope, and you'll gain an understanding of trajectory which is transferable to other scopes. If your load takes 36 MOA to get to 1000 yards, for example, that will be true of any MOA scope, whether the click value is 1 MOA per click, 0.5, 0.25, or 0.125.