Rifle Scopes 2nd Focal Plane. Mil to MOA. (?)

[libertyman777]

I need someone to check my math. I realize that I'll need to setup at the range to be 100% but I want to make sure my math is right.

I've got a Vortex Viper 6.5-20x50 Mildot that mils at 14x but the turrets are MOA. If I understand correctly I can change the magnification and make the reticle subtend in MOA.

So in order to have the mildots subtend 4 MOA, I divide 3.438 by 4. This equals .8595. Then I multiply 14x magnification by 1.163 which gives ~12x.

If I'd like to have it subtend 3 MOA, I perform the same operation dividing 3.438 by 3. This works out to 16x.

19x should equal 2.5 MOA.

Is this correct?

 

[_Windrider_]

Re: 2nd Focal Plane. Mil to MOA. (?)

This about summed this up for me. I hope someone responds because I would like to know.

Sorry I dont have anything constructive to offer.

 

[libertyman777]

Re: 2nd Focal Plane. Mil to MOA. (?)

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: TacticalDillhole</div><div class="ubbcode-body">

This about summed this up for me. I hope someone responds because I would like to know.

Sorry I dont have anything constructive to offer. </div></div>

Now that's funny.

 

[libertyman777]

Re: 2nd Focal Plane. Mil to MOA. (?)

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: DFOOSKING</div><div class="ubbcode-body">The easy way to do it....get a target up with grid lines spaced in MOA (1.047" @100yds)and make sure your exactly 100yds away.

Look at the target and change the magnification till you get the MOA spacing you desire. I doubt you'll be able to get a 1 MOA per mil spacing...but 3 MOA per mil spacing could be done easily enough.

No math required to figure this out. Make sure to mark your magnification dial where that is in relation to the index mark. </div></div>

I don't think I could even get 2 MOA out of the magnification I have available. This method will be required to verify for sure. I don't know if I've ever seen a target marked in MOA. I think I can get by just marking one up myself but I'd like to know if I'm thinking right with the math before I mark something up and head to the range.

 

[E. Bryant]

Re: 2nd Focal Plane. Mil to MOA. (?)

Your math is correct. Obviously, you'll need to verify the performance of this method at the range, since magnification markings are usually inaccurate.

 

[_Windrider_]

Re: 2nd Focal Plane. Mil to MOA. (?)

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: libertyman777</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: DFOOSKING</div><div class="ubbcode-body">The easy way to do it....get a target up with grid lines spaced in MOA (1.047" @100yds)and make sure your exactly 100yds away.

Look at the target and change the magnification till you get the MOA spacing you desire. I doubt you'll be able to get a 1 MOA per mil spacing...but 3 MOA per mil spacing could be done easily enough.

No math required to figure this out. Make sure to mark your magnification dial where that is in relation to the index mark. </div></div>

I don't think I could even get 2 MOA out of the magnification I have available. This method will be required to verify for sure. I don't know if I've ever seen a target marked in MOA. I think I can get by just marking one up myself but I'd like to know if I'm thinking right with the math before I mark something up and head to the range. </div></div>

MOA Targets

 

[libertyman777]

Re: 2nd Focal Plane. Mil to MOA. (?)

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: TacticalDillhole</div><div class="ubbcode-body">

MOA Targets </div></div>

Thanks for the link.

 

[sscoyote]

Re: 2nd Focal Plane. Mil to MOA. (?)

Eric's right--it's an inversely proportional equation since as magnification INCREASES reticle subtension DECREASES. The calculations will almost certainly be good enough for downrange zeroing but probably not precise enough for rangefinding [that'll have to be measured probably]. I have measured reticle subtensions to a pretty good degree of accuracy by ranging targets at known different distances, then reverse milling subtension and averaging those measurements. I believe it's possible to obtain an accuracy level of .1 MOA using this method though that's just a theory of mine...really.

 

[_Windrider_]

Re: 2nd Focal Plane. Mil to MOA. (?)

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: libertyman777</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: TacticalDillhole</div><div class="ubbcode-body">

MOA Targets </div></div>

Thanks for the link.

</div></div>

ALso, here is a bunch from Storm for free...... Storm Tactical

 

[gebhardt02]

Re: 2nd Focal Plane. Mil to MOA. (?)

I'm not sure about determining the magnification of the scope itself but if you accurately measure your target out at 100 yds, and have marks that line up to exactly 4.188" (4 MOA X 1.047") and reduce your magnification so that your mils line up exactly on those marks, you'll then have MOA spacing of the reticle to match your turrets.

You could also place this target at 50 yds and use 2 Mils instead of the 1 mil.

The next thing you'll want to do is box test your turrets to verify they indeed track in true MOA and not IPHY. And as stated above, mark your power ring once you find the correct magnification.

I have my Nightforces calibrated like this as I also have Mil reticle and MOA turrets and have used my MOA comeup values through my reticle for center hits out to 500 yds. Good luck, it is an easy way to have SFP scope and make a mil reticle match your MOA turrets.

Geb