Rifle Scopes formula for mil-dots=2 mils?

[Shiraz]

Is there a known standard for variable power SFP scopes where the mil-dots are = to 2 mils?

On all the scopes I have tested, if I reduce the magnification to half the value where the mil-dots= 1 mil,(ie. 12x to 6x) the value of a mil measures the distance value of 2 mils. Is this consistant to all scopes?
or
conversly if the scope has a ful mil value at 10x and you increase the magnification to 20x does the value of a mil in the reticle = .5mil?(I have not tested one of these but some manufactures make this type)

thanks.

 

[Brasscow]

Re: formula for mil-dots=2 mils?

Theoretically, yes that would hold true for all scopes. That being said, I wouldn't trust the little marks on the "zoom ring" to give me an exact indicator of "zoom level". The zoom range is all a reference to the scopes own focal length. So going from 5x to 10x would effectively double the focal length of the scope and halve the linear value of the mil-dot. Whether or not the marks on the zoom ring are accurate is an entirely different question. This can be tested, though. If you're not sure of a good way to test it I can write something up, just let me know.

 

[azimutha]

Re: formula for mil-dots=2 mils?

As brasscow stated, "Theoretically, yes..."

You could try a test like putting the scope on its advertised ranging power, e.g. 10X. In its simplest form, run a test on a target like this: At 10X fire a round, then hold two mils over and fire again. Then switch to 20X and run the same test, holding over 1 mil. At 5X, hold over 4 mils. In all cases, @ 100 yards you should be firing pairs of shots that are the same distance apart (2 mils on the target, i.e. 7.2"). Obviously, this is highly dependent on how well you and the rifle can shoot in the first place.

My ultimate $.02: Start looking for an FFP mil-dot scope. I'm not trying to be a smartass when I say this. Although there are some drawbacks to the reticle changing size, your mil scale in the scope will always be relative to the target rather than the magnification.

 

[Brasscow]

Re: formula for mil-dots=2 mils?

Firing shots isn't required to test it and would really only introduce error. You just need an object of known size at a known distance. For instance, mark exactly what 2 mils subtend at 100yds (7.2 inches or whatever it is) on a piece of paper and place it at 100yds. Adjust scope power until the 2-mil marks align with each edge of the mark you placed on the paper. Then zoom scope out until it takes one reticle-mil to subtend the same distance (edge to edge of the mark). That's your half-zoom range. Hopefully you can continue from here without guidance, or you might be a retard...

 

[eleaf]

Re: formula for mil-dots=2 mils?

I know that my Bushnell Elite 4200 6-24x50 actively advertises this as a feature. The mils are correct at 12x (marked in red on the zoom ring), but they tell me I can use it at 24x (just divide the number of mils by 2, and at 6x multiply them by 2.

As one poster already mentioned, it depends on how accurate the markings on your zoom ring are.

 

[sscoyote]

Re: formula for mil-dots=2 mils?

My Nikon Buckmaster is 66% of the mil cald. power of 12 (2.4" between dots measured) when applied at 18 (12 is 66% of 18). Some power rings are correct and some aren't.

 

[TOP PREDATOR]

Re: formula for mil-dots=2 mils?

test it by posting a target at 100 yards, hold a 1 mil high, if it hits 3.6" high, you know you are on. if you are not on, change the power ring to another power, take another shot, repeat until you get 3.6" high. this'll be your "10x" to use for ranging. then....


Mil FORMULA: SIZE in inches (H OR W) DIVided by # OF MILS times X 25.4 (METERS) OR 27.778 (YARDS)

so if you have a deer (16" average from top of back to bottom of rib cage)and you are reading 3 mils on "10x" through your scope...148 yards

16" divided by 3 mils, times 27.778 = 148yards (135.4) meters

MIL - 1 MIL IS 3.6" AT 100 YARDS ON 10X (CENTER OF DOT TO CENTER OF DOT)

1 METER IS 1.0936 YARDS
1 MOA "CLICK" IS 1.04719756"

 

[fillmore]

Re: formula for mil-dots=2 mils?

Brasscow is right about shooting to see introducing error. I would just put a 3.6" mark at 100yds. Zoom untill you you fit 1 mil on that mark and that is where your scope is right. Mark
it on your scope.

 

[bigwheeler]

Re: formula for mil-dots=2 mils?

36" and 10 mils will be a lot more accurate.

 

[fillmore]

Re: formula for mil-dots=2 mils?

This is true,bigwheeler.

 

[azimutha]

Re: formula for mil-dots=2 mils?

True, shooting would not actually confirm. Just measure like he said.