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Rifles, Reloading, Optics, Equipment
Rifles, Bullets, Barrels & Ballistics
Need some help extrapolating my drop data.
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<blockquote data-quote="Michael Eichele" data-source="post: 373434" data-attributes="member: 1007"><p>You have illustrated exactly why I start drop tests from a 300 yard zero instead of a 100 yard zero. Doing it the way you are doing it will drive you nuts, as you are finding out. There is too much going on under 300 yards and it is hard to get a true 100 yard zero to begin with. If you are .3" off center you might call that a perfect 100 yard zero when in fact, it really is not good enough. Now if you are .3-.5" off at 300 yards, the effects of that are very minimal. You can still test at 100-300 yards so you know where your dial is, however, for testing purposes, starting at 300 yards where things have settled down helps tremedously. Zero at 300 and shoot 350, 400, 450, 500, 550 and 600 yards and then try and match those numbers with your program. I would be willing to bet you will find a MUCH closer match. If it still doesnt match well, then change your BC in the program until it does match. I think that you will find that somewhere between .640-.660 will do the trick. Published is .648 but I have seen this vary with velocity and other factors. .648 is darn close though for a factory published value.</p><p></p><p>From there, your sub 300 yard values are very close even if they appear to be off a bit at times. It helps if you fire all those loads over the chrony so you can decern what is going on and get a better average.</p><p></p><p>Aside from that, it does seem that 2844 is a bit on the fast side for the 208 in a 308???????? Is your chrony accurate?</p></blockquote><p></p>
[QUOTE="Michael Eichele, post: 373434, member: 1007"] You have illustrated exactly why I start drop tests from a 300 yard zero instead of a 100 yard zero. Doing it the way you are doing it will drive you nuts, as you are finding out. There is too much going on under 300 yards and it is hard to get a true 100 yard zero to begin with. If you are .3" off center you might call that a perfect 100 yard zero when in fact, it really is not good enough. Now if you are .3-.5" off at 300 yards, the effects of that are very minimal. You can still test at 100-300 yards so you know where your dial is, however, for testing purposes, starting at 300 yards where things have settled down helps tremedously. Zero at 300 and shoot 350, 400, 450, 500, 550 and 600 yards and then try and match those numbers with your program. I would be willing to bet you will find a MUCH closer match. If it still doesnt match well, then change your BC in the program until it does match. I think that you will find that somewhere between .640-.660 will do the trick. Published is .648 but I have seen this vary with velocity and other factors. .648 is darn close though for a factory published value. From there, your sub 300 yard values are very close even if they appear to be off a bit at times. It helps if you fire all those loads over the chrony so you can decern what is going on and get a better average. Aside from that, it does seem that 2844 is a bit on the fast side for the 208 in a 308???????? Is your chrony accurate? [/QUOTE]
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Rifles, Reloading, Optics, Equipment
Rifles, Bullets, Barrels & Ballistics
Need some help extrapolating my drop data.
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