subtension of a tard moment

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12 years 2 months ago #13188 by 13fcolt
subtension of a tard moment was created by 13fcolt
So here I sit, spending time on the forums, watching some netflix, and studying my scopes. lebbenB had mentioned a mathematical solution in another thread for deciphering the subtension of a reticles markings at different magnification for a second focal plane scope.
So I went googling for this formula and came up with nothing. I found noting mentioned in any of my scopes manuals or manufacturer websites. I figured either no one uses it or knows about it, or more likely, Everyone already knew and I'm just the last to figure it out.

So I just fell out of the epiphatree and hit every branch on the way down. It's been right in front of me forever and I never noticed it. :banghead: Why is the Highest magnification divisible by the lowest? Smack goes the first branch, Then it all fell into place.
5.5x - 22x
@ 22x markings are 1/2 mil
@ 11x markings are 1 mil
@ 5.5x Markings are 2 mil
so I can still dope with these known values as if I had FFP. Now all I need is mil turrets to take out that nefarious conversion and I am good.


except for the leupolds. they use a 3.1 magnification ratio so I guess the increase would be as such. that ones not adding up the same so I'll have to get back to you.

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12 years 2 months ago #13192 by Akai
Replied by Akai on topic subtension of a tard moment
What about the wind and temp, got ant ideas on that :pray:

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12 years 2 months ago #13199 by 13fcolt
Replied by 13fcolt on topic subtension of a tard moment
yeah, what was it you needed help with?

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12 years 2 months ago #13212 by LebbenB
Replied by LebbenB on topic subtension of a tard moment

...lebbenB had mentioned a mathematical solution in another thread for deciphering the subtension of a reticles markings at different magnification for a second focal plane scope.


DUDE! I so totally forgot to answer your question. Please forgive me.

You've over-thought the formula. Let's say you have a mil-dot reticle in a 3-10x SFP scope. The reticle is "True" at 10x. At 5x, multiply the mil reading by 2, at 3x you multiply by 3.33.

If the reticle is "true" at a lower magnification, you would divide the mil reading at higher magnifications vice multiplying.

Sorry, bro...Sometimes I get CRS.

Wind Formulas
Mil: wind speed x bullet drift = Correction

Drift calculations: 100m - .003 mil
500m - .008 mil
1000m - .019 mil

MOA: Range (first digit) x Wind Speed = Correction

For a half value wind, multiply the correction by 2

Temps
For every 20 degree change in temp from the temp on the day the rifle was zeroed, add or subtract 1 MOA/.4 mils.
The following user(s) said Thank You: 13fcolt

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12 years 2 months ago #13224 by 13fcolt
Replied by 13fcolt on topic subtension of a tard moment
No worries brother. I honestly hadn't waited for any response, I was looking it up as soon as you had mentioned it.
I do over think this stuff all the time trying to get my head around it. As I frequently find myself more preoccupied with digits and decimals, I miss my blissful ignorance of simpler times when guestimating holdover and shooting by feel was good enough.

Thank you!

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12 years 2 months ago #13226 by Sharkey
Replied by Sharkey on topic subtension of a tard moment

13fcolt wrote: No worries brother. I honestly hadn't waited for any response, I was looking it up as soon as you had mentioned it.
I do over think this stuff all the time trying to get my head around it. As I frequently find myself more preoccupied with digits and decimals, I miss my blissful ignorance of simpler times when guestimating holdover and shooting by feel was good enough.

Thank you!


Oops, thought someone said my name...lol

You guys just go on talking french and I'll, um, watch spongebob or something for a while... :laugh:

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