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Did some chronoing today and I have a speed of 2772 fps @ 15 feet from the muzzle. I need to find a way to calculate back to MV. It should be close to 2780 fps. This is what I hoped for. I thought I could get 2800 fps with this rig and I have done that, but my best accuracy load is 20 fps shot of 2800 (but it is close enough for me!).

Load consists of H-4350, Lapua brass, Fed Match primers and 140 A-Max.

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XP,



Greetings! Taking into consideration such arithmetical ballistic variables as temperature, altitude from sea level for atmospheric pressure, powder burn from shot to shot, fouling drag on each subsequent shot in the bore, primer temperature, the minutia of BC variation as much as 5-10 points from bullet to bullet due to manufacturing tolerances, the allowances for a few FPS variation in the reading of the chronograph, powder weight, the way a charge sits in the case when fired etc, then being 8FPS off of your desired velocity is not that terrible a thing.



However, one might try setting up two chronographs, one at 15ft and one at 30ft, calculate the difference in velocity between the two, and extrapolate that ratio back another 15ft closer to the muzzle, and you might be kinda close