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Rifles, Reloading, Optics, Equipment
Rifles, Bullets, Barrels & Ballistics
LoadBase 2.0 Question
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<blockquote data-quote="mattj" data-source="post: 292133" data-attributes="member: 8758"><p>I've shot over my chrony out to 200 yards to calc the DC values, and it really isn't as scary as it sounds... even if you or your rifle can only hold 1 MOA on that day, that's only a 2" group -- plenty of room to avoid your skyscreens. If you're at all nervous about your dope, put a second target out there to verify your zero before you move over to the target behind the chrono (also, a CED M2 is nice, since the expensive part doesn't have to be near the target). Remember to give plenty of time for the barrel to cool between shots -- try to get in all your shots at the four different ranges in while the environmental conditions are the same -- and use the average of a bunch of shots to help get 'good' data (of course, if your load has low ES/SD, your data will be better).</p><p></p><p></p><p>When I don't have the time/motivation to use the chrono method, I've had good luck using the JBM online calculator with the G7 drag function for the particular bullet -- I then enter all of the same data (except G1 BC and .500 to start) into Patagonia Ballistics and tweak the DC until things line up. I've been able to get the dope to match at every 100 yard increment out to 1000+ yards using this method. I then use that DC value with PB on my Pocket PC to adjust for conditions in the field. Seems to work pretty well.</p><p></p><p>Tweaking the drag function to match your known dope is one step better if you have really meticulous field data on your real-world drops (including environmental data) -- but the chrono method will generally yield the best data.</p><p></p><p>Remember, garbage in, garbage out!</p></blockquote><p></p>
[QUOTE="mattj, post: 292133, member: 8758"] I've shot over my chrony out to 200 yards to calc the DC values, and it really isn't as scary as it sounds... even if you or your rifle can only hold 1 MOA on that day, that's only a 2" group -- plenty of room to avoid your skyscreens. If you're at all nervous about your dope, put a second target out there to verify your zero before you move over to the target behind the chrono (also, a CED M2 is nice, since the expensive part doesn't have to be near the target). Remember to give plenty of time for the barrel to cool between shots -- try to get in all your shots at the four different ranges in while the environmental conditions are the same -- and use the average of a bunch of shots to help get 'good' data (of course, if your load has low ES/SD, your data will be better). When I don't have the time/motivation to use the chrono method, I've had good luck using the JBM online calculator with the G7 drag function for the particular bullet -- I then enter all of the same data (except G1 BC and .500 to start) into Patagonia Ballistics and tweak the DC until things line up. I've been able to get the dope to match at every 100 yard increment out to 1000+ yards using this method. I then use that DC value with PB on my Pocket PC to adjust for conditions in the field. Seems to work pretty well. Tweaking the drag function to match your known dope is one step better if you have really meticulous field data on your real-world drops (including environmental data) -- but the chrono method will generally yield the best data. Remember, garbage in, garbage out! [/QUOTE]
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LoadBase 2.0 Question
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