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Elon Muskox
4 years ago
The POI on the far end indicates all bullets are ~300 fps faster than the LabRadar unit thinks.
With a 140-gr Berger VLD and a 100-yard zero, (according to QuickTarget) that 300 fps difference would mean a vertical difference in POI of 7.4″ @400 yards.
So the crux of the biscuit is, why aren’t they falling that extra 7.4 inches?
It can’t be BC because the anomaly is consistent across several different brands of bullet & ammunition.
It isn’t likely the chrono is that far out of whack because charge weight enough to produce that additional ~300 fps MV should be leaving pressure sign. Neither is it likely that all the represented manufacturers’ loads would be over-charged to the same magnitude.
But it could be HOB, either incorrectly measured or incorrectly entered into the calculations. If the HOB were entered as 2.5″ lower than actual, with a 100-yard zero (according to QuickTarget) that would result in bullet strike @400 yards 7.5″ higher than predicted.
This article is filed under the category(s) Firearms,Guns and was published March 28th, 2022 by Herschel Smith.
If you're interested in what else the The Captain's Journal has to say, you might try thumbing through the archives and visiting the main index, or; perhaps you would like to learn more about TCJ.
The POI on the far end indicates all bullets are ~300 fps faster than the LabRadar unit thinks.
With a 140-gr Berger VLD and a 100-yard zero, (according to QuickTarget) that 300 fps difference would mean a vertical difference in POI of 7.4″ @400 yards.
So the crux of the biscuit is, why aren’t they falling that extra 7.4 inches?
It can’t be BC because the anomaly is consistent across several different brands of bullet & ammunition.
It isn’t likely the chrono is that far out of whack because charge weight enough to produce that additional ~300 fps MV should be leaving pressure sign. Neither is it likely that all the represented manufacturers’ loads would be over-charged to the same magnitude.
But it could be HOB, either incorrectly measured or incorrectly entered into the calculations. If the HOB were entered as 2.5″ lower than actual, with a 100-yard zero (according to QuickTarget) that would result in bullet strike @400 yards 7.5″ higher than predicted.