Metric MOA??

[airplanejoe]

Food for thought. Last week I bought a scope to use on my AR. Leupold 1-6X24. Not a cheap scope and USA manufacture. Took it to the range to zero my rifle and when I removed the adjustment covers saw that it read one click moves the poi  1cm per 100 meters. I think this scope was manufactured for the European market  (the box does say metric) and somehow stayed in the USA. I'm not unhappy with the scope and will keep it. A few minutes in my desk and I figured that, converting the correction to the English system, I can use one click moves the POI 0.36 in per 100 yds.
Has anybody else had the same experience?
aj

[Nashville Stage]

Sounds like your scope is calibrated in miliradians instead of MOA. 1 mrad = 1 meter per 1,000 meters. Adjustments on that scale are usually 0.1 miliradian per click, which would be 1cm per 100 meters.

[Dracomeister]

Airplanejoe, just think in 3 clicks per MOA instead of 4 and you'll be close enough! (but if you really want something to put you to sleep, here is a Retired Engineer's answer ... )

Several "approximations" of the angular distance of a milliradian are used in riflescope Manufacture. Mathmatically the SI derived unit for angle is the radian and 1 arcminute is equal to 0.000290888208666 radian. By inverting that you get 1 radian is equal to 3437.74677078 arcminute, but most scope manufacturers approximate that to 3400 (a few use 3,000).  Based on that, if you have a scope that has a Milrad reticle, and your adjustments are 1/4MOA per click, than it will take approximately 14 clicks to come up 1 milliradian.

As an easy approximation: 3.5 MOA ~1 milliradian (It's actually 1.018 milliradians but 0.018 milliradians is within my range of error, so it works for me.)

Going the other way, 3 tenths of a milliradian is approximately 1.03 minutes of arc, so if you have a milrad scope and want to move your poi a certain number of Minutes of arc, think of each click (0.1 milliradians) as 1/3 minute of angle.

If your turrets are 1/4 MOA per click, than 14 clicks should move your POI approximately 1 milliradian.
If your turrets are 1/10 milliradian per click, than 3 clicks should move your POI approximately 1 minute of angle.

Sorry, but I warned you!

[Matt8531]

It sounds like you have a MIL reticle with MIL turret scope setup. Be thankful as it is a much simpler setup than MIL reticle with MOA turret adjustments.

Most people equate MILs to "metric". Although it is base-10 system,  it's not based on any "natural" measurement like the SI/metric system; well maybe the radian, but that's another story.

1 "MIL" is 1/6280th of a circle (1m @ 1000m) vs.  1 "MOA" being 1/3600th of a circle (1.047"@100yd). Historically, sniper scopes came with MIL-dot reticles and MOA-adjustable turrets. The shooter would have to range a target using MILs, then convert comeups to MOA to hit the desired point of impact. When you have matched reticles there is no need to convert between systems and adjustments become simplified.

[airplanejoe]

Thanks for the replies folks,

The scope is very easy to use as long as I remember three clicks per MOA (approx.). My initial approx. was one click=0.36 in. It has a finer adjustment than the 1 click = 1/2 MOA scopes and a coarser adjustment than the 1 click = 1/4 MOA. Definitely useable and the glass is very sharp.

I'm not sure that it has anything to do with mils, at least I hope not. It is not a ranging reticle (German #4). Anyway, does the English system have a proprietary ownership on the term MOA (1" at 100 yds) or can the term MOA also applies to the metric system (1 cm at 100 meters). I don't know.

aj

[maxwell]

Anyway, does the English system have a proprietary ownership on the term MOA (1" at 100 yds) or can the term MOA also applies to the metric system (1 cm at 100 meters). I don't know.

One minute of angle is 1/60th of one degree. It has nothing to do with the metric system, and 1" per 100 yards is merely a convenient approximation. The instructor's manual has a pretty thorough explanation of this, btw…

[Nashville Stage]

Here is a good explanation of the details of MOA:
https://www.youtube.com/watch?v=VA2PZBD5Tjg

...and here's one for mils:
https://www.youtube.com/watch?v=S5AGsHSIsVo

Your scope definitely adjusts in mils. Be careful not to confuse the *reticle* with the adjustment increments, though. You don't have to use a mil-dot reticle with a scope that adjusts in mils. There are scopes out there that have a mil-dot reticle, but adjust in MOA (which isn't necessarily a good idea, though). In your case, you have a scope that adjusts in mils, and has a plain reticle. You could make a scope that adjusts in MOA & has a MOA-dot reticle (those are more rare, unfortunately).

Milliradians (mils) and MOA are just angular measurements, like degrees. How we translate those angles into a height or width at a given distance is where the math comes in. MOA is nice because 1 MOA happens to be really close to 1" @ 100 yards. Mils are nice because they equal exactly 1/1,000th of the distance. So 1 mil = 1 yard @ 1,000 yards, or 1 inch @ 1,000 inches, or 1 meter @ 1,000 meters, etc.

[airplanejoe]

I'm probably not asking the question the right way. I believe I have a very good understanding of the MOA concept as used in the Appleseed program. It is an angular measurement (1/60 of a degree). Sometime ago I used the concept in solving celestial navigation problems (way before Loran C/D or GPS). I also understand the math used to arrive at the linear value of "1.047…" per 100 yds, which is the distance subtended by the width of 1/60 of a degree at 100 yds.

My question, which really has no practical value is this: If MOA is an angular measurement (1/60 of a degree) and since degrees are degrees regardless whether one is using the English or the Metric system, is it valid to say the linear width of 1/60 of a degree is 1.047.../100yds or 1cm/100mts; depending on which system one is using? Or to say: the linear value of 1 MOA can be expressed in both, The English or the Metric system.

Or are Countries using the Metric system not using "degrees" as their angular measurement but using instead milliradians? I don't have a good answer.

Again, just an academic question. I'm beginning to believe that I'm walking through a mine field. Inquiring mind, I guess.

aj

[Ricochet Rabbit]

I'm probably not asking the question the right way. I believe I have a very good understanding of the MOA concept as used in the Appleseed program. It is an angular measurement (1/60 of a degree). Sometime ago I used the concept in solving celestial navigation problems (way before Loran C/D or GPS). I also understand the math used to arrive at the linear value of "1.047…" per 100 yds, which is the distance subtended by the width of 1/60 of a degree at 100 yds.

My question, which really has no practical value is this: If MOA is an angular measurement (1/60 of a degree) and since degrees are degrees regardless whether one is using the English or the Metric system, is it valid to say the linear width of 1/60 of a degree is 1.047.../100yds or 1cm/100mts; depending on which system one is using? Or to say: the linear value of 1 MOA can be expressed in both, The English or the Metric system.

Or are Countries using the Metric system not using "degrees" as their angular measurement but using instead milliradians? I don't have a good answer.

Again, just an academic question. I'm beginning to believe that I'm walking through a mine field. Inquiring mind, I guess.

aj

An adjustment of 1 moa will shift your poi 2.9 cm at 100 m.

[maxwell]

My question, which really has no practical value is this: If MOA is an angular measurement (1/60 of a degree) and since degrees are degrees regardless whether one is using the English or the Metric system, is it valid to say the linear width of 1/60 of a degree is 1.047.../100yds or 1cm/100mts; depending on which system one is using? Or to say: the linear value of 1 MOA can be expressed in both, The English or the Metric system.

Certainly 1 MOA can be expressed in other linear units; for instance, it is 2.909 cm per 100 meters. Did I do the math right? Since 1 MOA is 1 inch per 100 yards and 1 inch is 2.54 centimeters, I'd expect it to be more than 1 inch at 100 meters .

Or are Countries using the Metric system not using "degrees" as their angular measurement but using instead milliradians? I don't have a good answer.

Beats me. SI does a lot of bizarre things to satisfy a not-invented-here syndrome, and countries using the metric system may or may not have adopted all of them.

[Ricochet Rabbit]

An adjustment of 1 moa will shift your poi 2.9 cm at 100 m.

See if this helps:

[azmule]

My question, which really has no practical value is this: If MOA is an angular measurement (1/60 of a degree) and since degrees are degrees regardless whether one is using the English or the Metric system, is it valid to say the linear width of 1/60 of a degree is 1.047.../100yds or 1cm/100mts; depending on which system one is using? Or to say: the linear value of 1 MOA can be expressed in both, The English or the Metric system.

Or are Countries using the Metric system not using "degrees" as their angular measurement but using instead milliradians? I don't have a good answer.

Again, just an academic question. I'm beginning to believe that I'm walking through a mine field. Inquiring mind, I guess.

aj

You can use MOA with either, but the math is easier to do in your head using inches/yards - it just works out that way.  The neat thing about mils is that the math is equally simple to do in your head whether you're working in yards, meters, hands, or furlongs.  One mil is one one-thousanth of the distance regardless of the units you use to measure that distance.  Target size in [unit] x 1,000 divided by target size in mils = distance in [unit].