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Rifles, Reloading, Optics, Equipment
Rifles, Bullets, Barrels & Ballistics
G7 Ballistics
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<blockquote data-quote="Bull45cal." data-source="post: 350518" data-attributes="member: 9768"><p><span style="font-family: 'Times New Roman'"><span style="font-size: 12px">Tayhot,</span></span></p><p> </p><p><span style="font-size: 12px"><span style="font-family: 'Times New Roman'">This is a trial and error method, and some else may have a better one, but this is what I did. </span></span></p><p> </p><p><span style="font-size: 12px"><span style="font-family: 'Times New Roman'">Start @ the JBM Trajectory page. </span></span></p><p><span style="font-size: 12px"><span style="font-family: 'Times New Roman'">Select the bullet you want from the bullet list at the top of the page. <em>It must have "(Litz)" at the end, if you want a G7 BC.</em> </span></span></p><p><span style="font-size: 12px"><span style="font-family: 'Times New Roman'">Input all the information you would normally do on this page. </span></span></p><p><span style="font-size: 12px"><span style="font-family: 'Times New Roman'">Have the program calculate the trajectory, and either open another page, or copy and save the traj. data to something like MS Word. </span></span></p><p><em><span style="font-size: 12px"><span style="font-family: 'Times New Roman'">Here is where the trial and error starts. </span></span></em></p><p><span style="font-size: 12px"><span style="font-family: 'Times New Roman'">Go back (if you copy and pasted the data, or use the other page you opened and go to the JBM page) to the trajectory input page, and select "none" in the bullet list. </span></span></p><p><span style="font-size: 12px"><span style="font-family: 'Times New Roman'">Then use the manual input boxes to input your bullet data. </span></span></p><p><span style="font-size: 12px"><span style="font-family: 'Times New Roman'">Make a guess at what the G7 BC is, and plug it into the "BC" box (155gr .308 bullets start around 0.210, and 200+gr .308's are around the .320's). </span></span></p><p><span style="font-size: 12px"><span style="font-family: 'Times New Roman'">In the little pull down box next to the BC input, select "G7." </span></span></p><p><span style="font-size: 12px"><span style="font-family: 'Times New Roman'">Make sure all other data on the input page is the same as the first one you did (make sure you set the "Maximum Range" to at least 1000 yards on both). </span></span></p><p><span style="font-family: 'Times New Roman'"><span style="font-size: 12px">Now compare the drop, at the farthest range, of both trajectory outputs. If they do not match then the G7 BC you guessed needs to be changed. Go back to the previous page, and increase the BC number if you have more drop (with the BC you guessed) than the original, and vise versa.</span></span></p><p><span style="font-family: 'Times New Roman'"><span style="font-size: 12px">Keeping doing this until the numbers match perfectly. This will give you the G7 BC that JBM is using to calculate the trajectories for the "Litz" bullets in the library. </span></span></p><p> </p><p><span style="font-family: 'Times New Roman'"><span style="font-size: 12px">If you have any questions, or I missed a step, please post back.</span></span></p><p> </p><p><span style="font-family: 'Times New Roman'"><span style="font-size: 12px">Later,</span></span></p><p><span style="font-family: 'Times New Roman'"><span style="font-size: 12px">Shane</span></span></p></blockquote><p></p>
[QUOTE="Bull45cal., post: 350518, member: 9768"] [FONT=Times New Roman][SIZE=3]Tayhot,[/SIZE][/FONT] [SIZE=3][FONT=Times New Roman]This is a trial and error method, and some else may have a better one, but this is what I did. [/FONT][/SIZE] [SIZE=3][FONT=Times New Roman]Start @ the JBM Trajectory page. [/FONT][/SIZE] [SIZE=3][FONT=Times New Roman]Select the bullet you want from the bullet list at the top of the page. [I]It must have “(Litz)” at the end, if you want a G7 BC.[/I] [/FONT][/SIZE] [SIZE=3][FONT=Times New Roman]Input all the information you would normally do on this page. [/FONT][/SIZE] [SIZE=3][FONT=Times New Roman]Have the program calculate the trajectory, and either open another page, or copy and save the traj. data to something like MS Word. [/FONT][/SIZE] [I][SIZE=3][FONT=Times New Roman]Here is where the trial and error starts. [/FONT][/SIZE][/I] [SIZE=3][FONT=Times New Roman]Go back (if you copy and pasted the data, or use the other page you opened and go to the JBM page) to the trajectory input page, and select “none” in the bullet list. [/FONT][/SIZE] [SIZE=3][FONT=Times New Roman]Then use the manual input boxes to input your bullet data. [/FONT][/SIZE] [SIZE=3][FONT=Times New Roman]Make a guess at what the G7 BC is, and plug it into the “BC” box (155gr .308 bullets start around 0.210, and 200+gr .308’s are around the .320’s). [/FONT][/SIZE] [SIZE=3][FONT=Times New Roman]In the little pull down box next to the BC input, select “G7.” [/FONT][/SIZE] [SIZE=3][FONT=Times New Roman]Make sure all other data on the input page is the same as the first one you did (make sure you set the “Maximum Range” to at least 1000 yards on both). [/FONT][/SIZE] [FONT=Times New Roman][SIZE=3]Now compare the drop, at the farthest range, of both trajectory outputs. If they do not match then the G7 BC you guessed needs to be changed. Go back to the previous page, and increase the BC number if you have more drop (with the BC you guessed) than the original, and vise versa.[/SIZE][/FONT] [FONT=Times New Roman][SIZE=3]Keeping doing this until the numbers match perfectly. This will give you the G7 BC that JBM is using to calculate the trajectories for the “Litz” bullets in the library. [/SIZE][/FONT] [FONT=Times New Roman][SIZE=3]If you have any questions, or I missed a step, please post back.[/SIZE][/FONT] [FONT=Times New Roman][SIZE=3]Later,[/SIZE][/FONT] [FONT=Times New Roman][SIZE=3]Shane[/SIZE][/FONT] [/QUOTE]
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