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Rifles, Reloading, Optics, Equipment
Rifles, Bullets, Barrels & Ballistics
Riddle me this? Ballistic calc vs reality mismatch...
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<blockquote data-quote="WiscGunner" data-source="post: 1981114" data-attributes="member: 97288"><p>I am sure you may be doing some of this but here goes...</p><p></p><p>Sounds like you have most of the details down, some too much. Forget coriolis, spin drift and cross wind jump for now, especially at only 500yrds.</p><p></p><p>BC changes with velocity. Either use an app that allows for Banded BC or start with the middle velocity provided by Hornady on their website.[ATTACH=full]214423[/ATTACH] </p><p></p><p>I suggest G7 but depending upon the app both G1 and G7 will work if you stay consistent.</p><p>Put .343 into your calculator if it is set for G7</p><p>Put .683 into your calculator if it is set for G1</p><p></p><p>Not sure what your setup</p><p>Is but obviously. Do NOT use a lead sled. Shoot how you would shoot in the field for consistency. Use the same method for all distances to avoid variables in velocity and POA/POI shift from positions. </p><p></p><p>Get the absolute best zero you can. Guessing and rounding errors add up. 100yrd zeros are best as atmospherics don't factor in.</p><p></p><p>Input your actual average velocity of 10 random rounds into your app to start. This avoids ignoring drift in your powder drops. 30ES is not top precision ammo but fine for 500yrd hunting </p><p></p><p>f your velocity is taken using a Labradar or Magnetospeed with proper setup, trust it. Accurately measured velocity doesn't need to be tweaked.</p><p></p><p>Remember distance for your targets is measured from the turrets of your scope where adjustments are made and not from the muzzle or from the chronograph.</p><p></p><p>Shoot at 500 and measure the real world error from the app. Tweak the BC of the bullets to true your app. Typically only a .001 or 2. </p><p></p><p>DO NOT forget about environmentals. Too many people focus on the pressure, DA or temp change every 5 mins. Not that important. What is more important is time of day (position of light source in the sky) but not that important at only 500yds. Pay attention to this beyond 500yrds if trying to be precise.</p><p></p><p>The most important thing to pay attention to is mirage. There are 2 mirages to pay attention to. Barrel Mirage and Target Mirage.</p><p></p><p>Barrel Mirage will start on your 7Rem Mag at about 3 rounds but will vary depending upon barrel profile, suppressor, barrel color, powder choice, etc. This will cause the target image to float in the scope resulting in POI rising. This start after about 5rounds in my medium palma stainless 6.5 Creed and results in about .3" high at 100yrds. This starts at about 3rds in my 7SS steel barrel but longer in my 7SS proof barrel. Suppressors will increase barrel heat mirage. Suppressor mirage makes a suppressor cover required. I simply take a click off my dope</p><p></p><p>Target Mirage will also make your target move with the mirage waves like floating on water and will vary with ground to air temp differences.</p><p></p><p>Be sure you are not confusing Mirage with BC error.</p></blockquote><p></p>
[QUOTE="WiscGunner, post: 1981114, member: 97288"] I am sure you may be doing some of this but here goes... Sounds like you have most of the details down, some too much. Forget coriolis, spin drift and cross wind jump for now, especially at only 500yrds. BC changes with velocity. Either use an app that allows for Banded BC or start with the middle velocity provided by Hornady on their website.[ATTACH type="full"]214423[/ATTACH] I suggest G7 but depending upon the app both G1 and G7 will work if you stay consistent. Put .343 into your calculator if it is set for G7 Put .683 into your calculator if it is set for G1 Not sure what your setup Is but obviously. Do NOT use a lead sled. Shoot how you would shoot in the field for consistency. Use the same method for all distances to avoid variables in velocity and POA/POI shift from positions. Get the absolute best zero you can. Guessing and rounding errors add up. 100yrd zeros are best as atmospherics don’t factor in. Input your actual average velocity of 10 random rounds into your app to start. This avoids ignoring drift in your powder drops. 30ES is not top precision ammo but fine for 500yrd hunting f your velocity is taken using a Labradar or Magnetospeed with proper setup, trust it. Accurately measured velocity doesn’t need to be tweaked. Remember distance for your targets is measured from the turrets of your scope where adjustments are made and not from the muzzle or from the chronograph. Shoot at 500 and measure the real world error from the app. Tweak the BC of the bullets to true your app. Typically only a .001 or 2. DO NOT forget about environmentals. Too many people focus on the pressure, DA or temp change every 5 mins. Not that important. What is more important is time of day (position of light source in the sky) but not that important at only 500yds. Pay attention to this beyond 500yrds if trying to be precise. The most important thing to pay attention to is mirage. There are 2 mirages to pay attention to. Barrel Mirage and Target Mirage. Barrel Mirage will start on your 7Rem Mag at about 3 rounds but will vary depending upon barrel profile, suppressor, barrel color, powder choice, etc. This will cause the target image to float in the scope resulting in POI rising. This start after about 5rounds in my medium palma stainless 6.5 Creed and results in about .3” high at 100yrds. This starts at about 3rds in my 7SS steel barrel but longer in my 7SS proof barrel. Suppressors will increase barrel heat mirage. Suppressor mirage makes a suppressor cover required. I simply take a click off my dope Target Mirage will also make your target move with the mirage waves like floating on water and will vary with ground to air temp differences. Be sure you are not confusing Mirage with BC error. [/QUOTE]
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Riddle me this? Ballistic calc vs reality mismatch...
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