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- Oct 22, 2014
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Correction factors:
Rule of thumbs to get close first, and then how to get your actual correction factor for your gun specifically.
Standard base (average gun)=
100- 0
200- .5
300- 1
400- 2
500- 3
600- 4
So what happens when you have a combo that shoots faster than 2800’ish fps or slower than 2,500’ish with a low BC? General rule is “Bad Gun”, “Average Gun”, “Good Gun”.
Average is the standard above.
Bad= Add .5 mils past 300 to the base.
Good= Take .5 mils off the base past 300 from the base.
How I did @grappling_hook 270 combo is to use the corrections. The BC is .4, but the MV is above 2,900’ish. That means is a “good gun”. He gave 480 yards, base is “2.8 mils”, but it’s a “good gun”, so take .5 mils off. The correction is “elevation 2.3 mils”. How well does it work? The actual correction is 2.2 mils at 5K DA. That’s a .1 mil error= 1.7 inches. Having never shot the rifle, didn’t put it into a calculator, and with 5’ish seconds of getting the range/gun info, I would have killed any big game animal on earth.
If it’s a “Bad Gun”. That is low MV, and/or low BC, add .5 mils to the base. Do not let the numbers overwhelm you. This takes less than 30 minutes to have a solid handle on it with paper practice.
Think critically: Who has a higher chance of killing an animal given all else being equal- a person that needs to look at a drop chart for both wind and elevation adding that time to make the shot? Or a person that can do it in their head in less time than it takes to chamber a round?
Rule of thumbs to get close first, and then how to get your actual correction factor for your gun specifically.
Standard base (average gun)=
100- 0
200- .5
300- 1
400- 2
500- 3
600- 4
So what happens when you have a combo that shoots faster than 2800’ish fps or slower than 2,500’ish with a low BC? General rule is “Bad Gun”, “Average Gun”, “Good Gun”.
Average is the standard above.
Bad= Add .5 mils past 300 to the base.
Good= Take .5 mils off the base past 300 from the base.
How I did @grappling_hook 270 combo is to use the corrections. The BC is .4, but the MV is above 2,900’ish. That means is a “good gun”. He gave 480 yards, base is “2.8 mils”, but it’s a “good gun”, so take .5 mils off. The correction is “elevation 2.3 mils”. How well does it work? The actual correction is 2.2 mils at 5K DA. That’s a .1 mil error= 1.7 inches. Having never shot the rifle, didn’t put it into a calculator, and with 5’ish seconds of getting the range/gun info, I would have killed any big game animal on earth.
If it’s a “Bad Gun”. That is low MV, and/or low BC, add .5 mils to the base. Do not let the numbers overwhelm you. This takes less than 30 minutes to have a solid handle on it with paper practice.
Think critically: Who has a higher chance of killing an animal given all else being equal- a person that needs to look at a drop chart for both wind and elevation adding that time to make the shot? Or a person that can do it in their head in less time than it takes to chamber a round?
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