N/A Math formula to know how much to compensate.

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Emu

Emu

Member
Jan 15, 2020
4,057
3,102
Queretaro, Mexico
I own a scope with a lot of references.

I mounted this scope to the FX Panthera Compact.

First I learned how much to compensate at 88 yards and later on how much at 190 yards.

Then I decided to try a formula to get to know how much to compensate knowing the distance after a measure with the range finder.

What I learned is that dis-acceleration increases need of compensation: ratio at 77 yards of 0.1 vs ratio at 190 yards of 0.135.

Then I decided to create four blocks of formulas for four ranges 50 to 80, 90 to 110, 120 to 140 and 150 to 190.

After a measure with the range finder I insert the distance in the closer applicable formula and get how many compensation in that scope is needed.

The result is much more close than my previous instinctive/memory one I use to apply for compensation.

Well many of you would tell me that there's a software that you can feed and that gives you a number. Yes, I know.

The difference with this new way I am applying since yesterday is that is a tailor made for specific scope already mounted on an specific rifle. All truth an empirical.

I am anxious to go hunting and applying the formula and see results.
 
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I was able to include an incremental constant to the formula to have only one formula. Now it shows same results as the one with steps of range.

This formula should be useful for anyone, just changing zero distance and including compensation at one distance in your scope.

Dropping and dis-acceleration should be really close on the average fps we shoot.
 
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You’re at high elevation, right? If so, your formula will not work for the vast majority. The apps that you dismiss, like chairgun, do allow the user to select a scope, it’s height from the bore, particular ammo and speed, plus elevation and temperature, the latter of which greatly affect trajectory.

Edit: Queretaro ~6000feet ASL, so air pressure is around 75% of sea level, meaning that projectiles are subject to 25% less drag. Very nice if you’re shooting slugs!
 
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Emu said:
Well, I went hunting for a couple of hours and confirmed that in my environment it works well.
Click to expand...

That didn't answer my question, does the formula take into account ballistic coefficient? Would your formula work if you drastically changed either caliber or went from slug to pellet, or from wadcutter to diablo pellet? Inquiring minds would like to know your formula. Or is it pseudo-math working for your current setup/conditions/projectile combination?

-Matt
 
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Stubbers said:
That didn't answer my question, does the formula take into account ballistic coefficient? Would your formula work if you drastically changed either caliber or went from slug to pellet, or from wadcutter to diablo pellet? Inquiring minds would like to know your formula. Or is it pseudo-math working for your current setup/conditions/projectile combination?

-Matt
Click to expand...
No Matt, this formula I made is too basic. It does not include BC. It just a matter of what I saw in regard of compensation at 190 yards and at 88 yards with the JSB's 34 grain that I am actually shooting with my Panthera.

So there are some many complex ingredients to take into consideration that it won't worth it to be shared.
 
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Emu said:
No Matt, this formula I made is to basic. It does not include BC. It just a matter of what I saw in regard of compensation at 190 yards and at 88 yards with the JSB's 34 grain that I am actually shooting with my Panthera.

So there are some many complex ingredientes to take into consideration that it won't worth it to be shared.
Click to expand...

Understood.

-Matt
 
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