Why make an mrad scope without 10X?

They just retrofit an existing scope design.

3-9 has been popular for like 50 years.

That's a classic 3x root power right. 4-12x, 5-15x

Its only recently that scope makers started exceeding 3x root.

March set the world on fire with 10x root power... 2.5-25x, that was not all that long ago.

I don't agree that wide zoom range scopes like that are an advancement as there are a number of optical mechanical things that are sacrificed to arrive at that functionality.

Kind of a.. just because you can, does not mean you should.

To your root question... 2.5-10x is available out there where they use a 4x root power.

MRAD is irrelevant in relation to magnification... They are just playing into the recent MRAD craze of military wanabeees.
 
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Scott Bear said:
Doesnt the mil dot concept only work with a magnification of 10 since it's a 1:1000 ratio? Or have the reticle made to work with a certain magnification?
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Scope manfs will scale the reticle and let customers know the subtension. If you are concerned about consistent subtension regardless of mag used, then consider a FFP optic.

SFP optics have a varying subtension as you change the mag BUT most manfs will have the subtension at a common spacing at the more common mag used... again, all this is indicated by the manf in their specs.

There is nothing special about a 10X wrt to 'making' a reticle work.

Jerry
 
So the magnification and the reticle do have to work together and making distance calculations would be easier at 10X? Just seems like this wouldn't be as easy with a scope zoomed to 9X.
 
Not certain that I follow your last question - the variable power scope likely has one power that is identified - assuming it has the more common Second Focal Plane (SFP) reticle - it will say so in the book that it came with - that is the only power that the reticle marks are truly Mill-rads. I think that is what you are asking?? I have a fixed 12x SWFA scope with mill-rad reticle - because the scope's power can not change, those marks are truly "mill rad" all the time. My acquaintance has same brand and model of scope in 20x - same deal - if I can see what he sees, we both get same number of "mill-rad" to correct.
 
Your question just "clicked" - you want to use the mill-rad marks for range estimation - on a variable power scope, that uses SFP reticle, there is only one power where that will work - should be marked - different colour or whatever. A "First Focal Plane" (FFP) reticle changes as the power changes, so the "mill-rads" stay the same - depends which type of scope that you have - says that in the booklet that came with it.
 
Right. So some scopes have a reticle set up for the highest magnification (or whatever it might be) on a SFP scope. On a 3-9X40 scope it would be at 9X and there would be a formula for ranging your target (knowing the size of your target) that would not be the same as the formula used for a mil dot fixed 10X scope?
 
The formula - a mill rad is a measure of arc - like saying so many degrees, or parts of a degree. So if an object is guesstimated to be 36" tall, or 52 mm wide, then a mill-rad scope is used, with "accurate" mil rads - and count how many mil rads that thing is using up. Some math, and you work out what is the range to that thing. The magnification that you used to get there, does not matter, except to more precisely count the mil rad hash marks. But have to have a guess of the dimension of the thing that you are ranging, then count the number of mil-rads - do the math and come up with a range estimate. If you got 23 mil rads at 10 power, or 23 mil rads at 5 power - and they were truly 23 mil rads, you would calculate to the very same range.
 
Potashminer said:
The formula - a mill rad is a measure of arc - like saying so many degrees, or parts of a degree. So if an object is guesstimated to be 36" tall, or 52 mm wide, then a mill-rad scope is used, with "accurate" mil rads - and count how many mil rads that thing is using up. Some math, and you work out what is the range to that thing. The magnification that you used to get there, does not matter, except to more precisely count the mil rad hash marks. But have to have a guess of the dimension of the thing that you are ranging, then count the number of mil-rads - do the math and come up with a range estimate. If you got 23 mil rads at 10 power, or 23 mil rads at 5 power - and they were truly 23 mil rads, you would calculate to the very same range.
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Only in a First Focal Plane scope?
 
Scott Bear said:
Right. So some scopes have a reticle set up for the highest magnification (or whatever it might be) on a SFP scope. On a 3-9X40 scope it would be at 9X and there would be a formula for ranging your target (knowing the size of your target) that would not be the same as the formula used for a mil dot fixed 10X scope?
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Yes, that is correct. It can be the highest magnification of the scope, but could also be a lower magnification. The scope manual should give you all the info you need about your scope and its reticle sub-tensions.
 
Scott Bear said:
Wait, it wouldn't matter if it could only be used at a certain magnification.

Found a manual. Doing some reading.
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On a SFP scope the reticle subtensions will only be correct at a specific magnification power on that scope. On a FFP scope it doesn't matter which magnification power you use the reticle subtensions are always usable and correct.
 
Scott Bear said:
Right. So some scopes have a reticle set up for the highest magnification (or whatever it might be) on a SFP scope. On a 3-9X40 scope it would be at 9X and there would be a formula for ranging your target (knowing the size of your target) that would not be the same as the formula used for a mil dot fixed 10X scope?
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No. The formula is the same. You just have to know if you are working in inches and yards and MOA, or mm, m and Mrad.

On a SFP scope the manufacturer makes the reticle hash marks fit a Mrad/metric scale (or MOA/imperial scale) at a specific magnification as stated and marked on the zoom ring.

You don't use the magnification power number in the milling equations numbers for the milling calculations for range distance or target size. You use the proportions of the MRAD hash marks relative to the known target size, or the known distance (you need to know one or the other), at the stated specific magnification that the reticle is made for in a SFP scope.

SFP scope calculation for distance, set at specific milling magnification as specified:

(target size in mm) / target size in hash marks

example: (300 mm square target) / 0.8 Mrad = 375m


SFP scope calculation for target size, set at specific milling magnification as specified:

(Known distance in m) x (size of target in Mrad as seen in reticle)

example: (500m) x (0.7 Mrad) = 350mm or 35 cm target size in height or width (depending if you used vertical or horizontal hash marks).


On a FFP scope milling works on any magnification, but the price you pay is a tiny almost disappearing reticle at low mag, and a thick reticle at higher mags.

Milling target size and distance does not use the power number in the equation numbers.
 
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Gets very confusing for us "old guys". US Military apparently started this - is also a form of it from USSR days - so reticle is set up with mill-rad hash marks - gets you a range estimate in meters. However, scope's turret adjustments are in MOA, not mil-rads - so have to convert again, to adjust scope turret, for that cold barrel shot. The set up gets you a range in meters, but sight adjustments based on yards. Made sense to someone, I guess. I have a Bushnell Elite 10x that is exactly that way - mil-rads in the reticle, MOA on the turrets. Was main reason I went with a SWFA Mil-Quad - mil-rads in the reticle, mil-rads on the turrets (actually 10ths of mill rads on the turret). Works "best" to just forget about yards and MOA - go "metric" all the way... From others, appears is often used to "walk in" long range shots - so want both shooter and the spotter to be talking in same units for how much to adjust or to hold off. Don't think that was the original military intent - I think was to range, then one cold barrel shot.
 
You are over thinking it. Say the scopes reticle is calibrated to 6x magnification to be a true mill rad. You do the math get the range. Then zoom up to 9. To get the accurate range you need to subtract 50% of the total mil hash marks counted. Say you count 10 the math would need 50% of that to work out so 5 mil rads is what you would use. Now if you zoomed down to 3x you would have to double the amount of mill rads you counted. You would count 2.5 mill. Double it you get 5. It's all about scaling.

The thing with using a mil rad reticle to range is your equation outcome is only as good as your input numbers. Put junk in get junk out like everything else in life. You need to be as close as possible with your input numbers to get an accurate range. Around here a fence post is normally 4 feet tall. Use a known object to get a good estimate

My 6.5-20 Viper is calibrated at 14x which is stupid because 14 doesn't go into 20 and 6.5 doesn't go into 14. You have to go back to long division from elementary school.

Range finders and a ballistic app were created for a reason and are easier to use. Or get the sig bdx scope and range finder and download the app. Range the target, range finder sends info to phone, phone does the ballistics, phone sends info to scope, scope moves point of aim, send freedom seed to target
 
He's just confused about FFP or SFP

Old military scopes were fixed 10x so it did not matter if it was FFP or SFP.

The magnification was irrelevant, but scaled to be correct to the reticle.
 
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