Adjusting a mil scope

[Ned Ludd]

Shooters often refer to group spread or shot displacement using linear measurements, in other words, how far apart the holes were located on the [flat] target face. In trigonometric terms, what we're really refering to is arc length. A given angle subtends a specific arc length for a circle with a defined radius. As illustrated above, the arc length subtended by a given angle for a circle with a defined radius is really not flat, as it is part of the circle. However, at the radii we're typically talking about in shooting discussions, the circle is so large that we consider its arc to be effectively flat over short lengths for the purposes of measuring group size.

Using a milliradian scope is no different that using an MOA scope, milliradians are merely a larger angular adjustment. It is no different than using a scope with 1/8th MOA clicks versus a scope with 1/4 MOA clicks. If one or the other is used regularly, it will become the new normal. When switching back and forth between the Mil and MOA scopes on a regular basis, one may need to keep their wits about them a little more than normal, but it's completely doable.

To use the reticle effectively for adjusting point of impact, one has to be able to see the reticle clearly, and the reticle must be a 1st focal plane, (meaning the reticle changes size as the scope magnification changes) to use effectively at any magnification. In contrast, a 2nd focal plane scope must be set at its "calibration" magnification or some readily convertible fraction thereof (i.e. one half or double). The reticle in a 1st focal plane scope remains proportional throughout the magnification range. The reticle in a 2nd focal plane scope does not change in size as the magnification is changed, thus a 2nd focal plane reticle has to be "calibrated" to represent linear distances (i.e. arc lengths) at some specific magnification. In order to use a 2nd focal plane reticle to estimate necessary scope adjustments based on impacts, the scope needs to be set at the "calibration magnification", or at some fraction of it that can easily be manipulated mentally. For example, if a 2nd focal plane scope reticle is "calibrated" at 40X magnification, one could adjust the point of impact using the reticle with the scope set at 20X, but would have to remember/know that image size with respect to the reticle had been cut in half (i.e. 40X to 20X magnification). Thus, the arc length indicated by the reticle would also need to be halved in order to make the correct scope adjustment. Not having to make such mental calculations is one of the big advantages of a 1st focal plane reticle.

 

[SecondsCount]

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The spotter can spot through his scope if he needs a reticle but calling in any linear is not the way. Better to use the target dimensions like "half a target right, hold half a target left" instead of any linear.

This is exactly how I do it but the original post asked about how to adjust if the spotter is giving adjustments in inches.

It isn't always easy to find a good spotter so sometimes you take what you can get.

 

[Rob01]

This is exactly how I do it but the original post asked about how to adjust if the spotter is giving adjustments in inches.

It isn't always easy to find a good spotter so sometimes you take what you can get.

And my points have been to forget inches. Inches will tell him nothing more than the reticle or using target size will and will slow him down as he will start doing head math. Him and his friends need to learn how to use their equipment and not learn to work around it and make their life harder.

 

[Mike Casselton]

I have to agree with Rob on this.

I read all the nonsense of converting mils, moa, iphy and skittles to try and figure out stuff.

Then I bought my first Mil/Mil scope. Mounted it, took it to the range and zeroed it.

It all became abundantly clear while zeroing the rifle.
Holy Crap!!!
The reticle matched the turrets. It was literally a ruler floating within my scope.
It didn't matter if I was shooting paper, steel, rocks or golf balls. If I missed by .3mils left my correction was .3 right.

I learned very quickly not to dial wind correction. It's just too slow and the wind constantly changes. It will also come back to bite you when you change distances and forget to make the windage correction.

There are times I will dial windage, but it's only when shooting a mile or more and I need 5+mils of wind correction.


Your spotter needs to call corrections in the same way you are seeing them. Mils.
If he's unable to do that, then use the plate size and call it in plates or portions of a plate.
Eg: if you are shooting a full IPSC at 500 yards and you miss 6" to the right, his call should be 1/3rd right, or, better yet, something like "come 1/2 plate left."
It won't be a center hit, it'll be just right of center if his call is correct and you make the actual correction.
Many, many times I've spotted for newer shooters and called corrections. Most will only correct half of what the call is. I don't know why they do it, but they do.
If the call is correct, learn to trust it.




For those that are speaking in terms of measuring the target with the reticle to determine distances. That's a completely different discussion and way more information than the OP needs at this point. It's just going to confuse him.

 

[Mike Casselton]

One more thing.

If you are shooting prone and unable to see your hits/misses, you need to get behind the rifle properly.
That's another completely different discussion.

 

[Rob01]

One more thing.

If you are shooting prone and unable to see your hits/misses, you need to get behind the rifle properly.
That's another completely different discussion.

I was going to mention that but didn’t want to bring that into the conversation. A very good point though.

 

[Mike Casselton]

I still sometimes find I'm playing little green Army man behind the rifle. I'm sloppy if I'm just spotting. When my buddy says, "your turn", I'll forget to square up. I need to just stay square anytime I'm behind the rifle.

This is what happens when you don't do it all the time. I plopped down, got the hog in the crosshair, and shot it at the brain stem. 90 yd shot and I barely saw it go down through the scope.

 

[DLT]

Thanks for all the replies and suggestions. I have been shooting sightrons moa 2 and 3 reticles. I sold one of them and decided to go with a ffp mil scope with finer subtensions to help with finer holds out at the distance I get to shoot at. I figure it was best to try mils on cheaper price scope vs a high end one incase I didn’t like it. From this forum and the interweb and many videos on the matter it looks like as long as the reticles match the turrets and ffp, spotting hits from behind the scope and correcting , one system so far to me doesn’t have an advantage over the other.

 

[Rob01]

Thanks for all the replies and suggestions. I have been shooting sightrons moa 2 and 3 reticles. I sold one of them and decided to go with a ffp mil scope with finer subtensions to help with finer holds out at the distance I get to shoot at. I figure it was best to try mils on cheaper price scope vs a high end one incase I didn’t like it. From this forum and the interweb and many videos on the matter it looks like as long as the reticles match the turrets and ffp, spotting hits from behind the scope and correcting , one system so far to me doesn’t have an advantage over the other.

Yup you can do the same thing with a ffp moa scope with matching reticle and knobs. Works the same but just a different graduation. This is why I cringe every time I hear someone say “I use moa as I think in inches so I couldn’t get used to mils”. Neither has anything to do with linear. If you can use moa then you can use mil. Just a different number to hold or dial. It really is that simple.