Range Report Drag Model Differences (G1 vs.G7 within 600 yards)

skatz11

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Jun 8, 2009
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What would be the correct drag model to use for a .223 (77gr SMK)? I'm using the shooter app on my droid. I have it set for G1 and the drop at 300 yards is fairly close to the published MV for the load I'm using (24gr AA2520) I've read that G7 is more accurate for HPBT bullets, however when I use the G7, I have to drop the MV significantly to match my drop data. I plan on collecting more data, but for now its driving me crazy not knowing what the correct approach should be with the ballistic calc.
 

gafferq2xl

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May 7, 2006
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Re: Drag Model Differences (G1 vs.G7 within 600 yards)

I wonder if the bc's you are using aren't quite right. Or, maybe the G1/G7 models you use have issues. This is from Applied Ballistics book by Brian Litz. Maybe they will help. I use the avg. published bc listed.

2cxb0p5.jpg
 

skatz11

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Re: Drag Model Differences (G1 vs.G7 within 600 yards)

Thanks! That did the trick. I had G1 BCs with the G7 model. Now I'm within 5 fps and it is close to the published MV.