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Rifles, Reloading, Optics, Equipment
Rifles, Bullets, Barrels & Ballistics
Help me figure out velocity and trajectory
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<blockquote data-quote="paphil" data-source="post: 620094" data-attributes="member: 17745"><p>There are several factors that are important when using a ballistic program to generate a drop chart. First and foremost , you cannot generate a good chart with inaccurate data. Your "o" has to be exactly on, be it 100 or 200 or 300. The distance to the targets must be exact, not 5 or 10 yards short or long. The atmospheric conditions, ie. temperature, altitude and barometric pressure must be precise. It is a simple thing to print out a generic drop chart using the mfg. BC and a guessed or chronographed velocity. This is just the first step. If you are shooting big game out to 500-600 yards, this generic chart will probably serve you well. If you want a precision chart, lets go to step 2! SHOOT YOUR DATA. your gun will be different than that generic chart. Using the generic chart as a guide, shoot at a mid range target and a long target. I usually start at 500 and then 700 and 950 and 1200 for my long target. I like to shoot a 4 shot group at each distance and record them carefully. It is not necessary to "O" at each range but we can calculate the true click value needed to be on at that range. If the generic chart says 16 clicks for 500 yards and my group is 5 inches high then I would record 13 clicks ( using 1/3 Moa clicks, I am 1 MOA high at 16 so 13 will be right on) Do this at each target and you have created your own ballistic curve for that gun. If you are using the Best of the west or G7 program here on the site , you now enter the long range data in the program and calculate. This will generate a chart that is much closer to your ballistic data. If you have a chronographed mv, float the BC. If not float the velocity before calculating. Now compare the data on this chart with your real data. The middle target data may be higher or lower than what comes up on the chart. By bumping the BC up or down .01 at a time and re calculating, your chart will come right in line with your real data. You will now have true BC and velocity for that bullet and a near perfect drop chart!</p></blockquote><p></p>
[QUOTE="paphil, post: 620094, member: 17745"] There are several factors that are important when using a ballistic program to generate a drop chart. First and foremost , you cannot generate a good chart with inaccurate data. Your "o" has to be exactly on, be it 100 or 200 or 300. The distance to the targets must be exact, not 5 or 10 yards short or long. The atmospheric conditions, ie. temperature, altitude and barometric pressure must be precise. It is a simple thing to print out a generic drop chart using the mfg. BC and a guessed or chronographed velocity. This is just the first step. If you are shooting big game out to 500-600 yards, this generic chart will probably serve you well. If you want a precision chart, lets go to step 2! SHOOT YOUR DATA. your gun will be different than that generic chart. Using the generic chart as a guide, shoot at a mid range target and a long target. I usually start at 500 and then 700 and 950 and 1200 for my long target. I like to shoot a 4 shot group at each distance and record them carefully. It is not necessary to "O" at each range but we can calculate the true click value needed to be on at that range. If the generic chart says 16 clicks for 500 yards and my group is 5 inches high then I would record 13 clicks ( using 1/3 Moa clicks, I am 1 MOA high at 16 so 13 will be right on) Do this at each target and you have created your own ballistic curve for that gun. If you are using the Best of the west or G7 program here on the site , you now enter the long range data in the program and calculate. This will generate a chart that is much closer to your ballistic data. If you have a chronographed mv, float the BC. If not float the velocity before calculating. Now compare the data on this chart with your real data. The middle target data may be higher or lower than what comes up on the chart. By bumping the BC up or down .01 at a time and re calculating, your chart will come right in line with your real data. You will now have true BC and velocity for that bullet and a near perfect drop chart! [/QUOTE]
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Rifles, Reloading, Optics, Equipment
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Help me figure out velocity and trajectory
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