Re: Lapua BC, ICAO or Metro?
Sierra does use Metro.
I'm not sure about Lapua, but I strongly suspect they would use ICAO.
-Bryan
Sierra does use Metro.
I'm not sure about Lapua, but I strongly suspect they would use ICAO.
-Bryan
Re: Lapua BC, ICAO or Metro?
I wouldn't worry too much about that.
Here are some things other than the atmosphere which affect the accuracy of ballistic calculations:
Variation in powder temperature.
Variation in chamber temperature.
Variation in primer performance.
Variations in case dimensions, including, but not limited to, neck tension.
Variations in bullet parameters.
Barrel vibration.
Shooter interaction with the rifle doing recoil.
Inability to properly measure wind, which also affects vertical point of impact.
The result of that is that a given ballistic program must be "tuned" to the rifle and load in use, so that the predictions more closely match field shooting performance. Some programs, like Field Firing Solutions, have explicit mechanisms for doing so. In others, varying the B.C. may be the best option.
I think it is best to use data from the longest possible distance to do these adjustments, since that is where the margin for error is the smallest.
So, I wouldn't worry too much about which atmospheric model was used by bullet manufacturers. The notion that any ballistic program is going to produce perfect results, especially from shot to shot, is laughable.
And I say that as a shooter with at least 5 ballistic programs.
The reason I most often miss a shot is not from a failure of my ballistic program, but from neglecting one of the fundamentals of marksmanship.
I wouldn't worry too much about that.
Here are some things other than the atmosphere which affect the accuracy of ballistic calculations:
Variation in powder temperature.
Variation in chamber temperature.
Variation in primer performance.
Variations in case dimensions, including, but not limited to, neck tension.
Variations in bullet parameters.
Barrel vibration.
Shooter interaction with the rifle doing recoil.
Inability to properly measure wind, which also affects vertical point of impact.
The result of that is that a given ballistic program must be "tuned" to the rifle and load in use, so that the predictions more closely match field shooting performance. Some programs, like Field Firing Solutions, have explicit mechanisms for doing so. In others, varying the B.C. may be the best option.
I think it is best to use data from the longest possible distance to do these adjustments, since that is where the margin for error is the smallest.
So, I wouldn't worry too much about which atmospheric model was used by bullet manufacturers. The notion that any ballistic program is going to produce perfect results, especially from shot to shot, is laughable.
And I say that as a shooter with at least 5 ballistic programs.
The reason I most often miss a shot is not from a failure of my ballistic program, but from neglecting one of the fundamentals of marksmanship.
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