The MOA Formula For Calculating MOA Clicks For A Shot Less Than 100 Yards If Zeroed At 100 Yards?
- Thread starter adn258
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Quote from the OP... IMO,it puts some context on what the question was. I'd round it,myself. The techno/academic arguement might have an element of merit in it and up to a point,the academic accuracy is OK to clarify.
But is the ego based whizzing contest adding anything to the thread?
But is the ego based whizzing contest adding anything to the thread?
There are definitely times when you need to go out to three places past the decimal--and even beyond. In this case, I agree, two places is going to get you close enough. Rounding to 1.05 gives a percent error of less than 0.3%.
And by the way, just for fun, approximating 1MOA at 100yards as 1" is the same as approximating pi as 3. That's probably a bit more approximation than anyone with a math background is going to be happy about--even if it turns out to be eminently practical for the application.
Aguila Blanca
Staff
The pedant in me feels constrained to point out that the "metric mile" is 1600 meters, not 1600 yards.Bart B. said:
That said, the approximation of 1 MOA being "equal" to 1 inch at 100 yards has been with us for a very long time, and it's close enough for probably 99.378 percent of shooters in the world.
Jim Watson
New member
The track and field "metric mile" race is only 1500 metres.
I'm a mathematician and round stuff like this all the time.There are definitely times when you need to go out to three places past the decimal--and even beyond. In this case, I agree, two places is going to get you close enough. Rounding to 1.05 gives a percent error of less than 0.3%.
And by the way, just for fun, approximating 1MOA at 100yards as 1" is the same as approximating pi as 3. That's probably a bit more approximation than anyone with a math background is going to be happy about--even if it turns out to be eminently practical for the application.
My range estimation at anything around a 100yds will likely mean way more than the MOA "actual" measure.
And can I hold within the difference that 0.047 difference from 1 means with either the rifle or a range finder? Oh, and what are the tolerances on the range finder?
Be honest; when was the last time you did a calculation requiring pi and rounded the value to 3?
If you’re saying that range estimation errors at around 100yds are likely to result in an error on the target that is larger than pi/3 - 1 inches, then I wouldn’t argue.
Besides, if you make it clear that what you mean by 1MOA is 1” per hundred yards, there’s really no error at all. It’s just a matter of being clear about what you mean when you say MOA.
The reason each of those has a different name (i.e. ‘statute mile’, ‘nautical mile’, ‘metric mile’, and ‘USA military radar mile’) is specifically because everyone agrees that they are different and need to be treated as different values. No one would ever suggest it’s reasonable to just randomly pick any one of those values and call it a mile without further explanation, or to round the number to some arbitrary precision and pretend that's the real value.
If we clearly state that the ‘shooters MOA’ is different from the mathematical definition of ‘MOA’, then there’s no confusion and no real problem. And, in most cases, even equating the two doesn’t really cause practical problems even though it is incorrect to do so and can cause confusion.
Worse than that, the term ‘metric mile’ is commonly used to refer to a 1500 meter distance as that is the common race distance in track and field that is closest to a statute mile. This is where there can really be confusion--when one term can refer to two distinct values.
Anyway, as long as things have sort of started leaning toward the pedantic, it’s probably worthwhile to point out that the ‘USA military radar mile’ is generally defined in terms of time, rather than distance It is equivalent to 12.36 microseconds—double the time required for a radar pulse to travel a nautical mile (1nmi = 1852 meters, about 2025 yards).
It’s kind of ironic that nautical miles have come up in this discussion because the nautical mile is also a measurement that relates to 1 MOA. In the same way that 1” is the rough equivalent of 1MOA with the angle measured at the shooter and the distance measured on the target at 100 yards, 1 nautical mile is also the rough equivalent of 1 MOA—with the angle measured at the center of the earth and the distance measured on the earth’s surface.
1MOA at 100 yards is about 1.047”
1MOA at 6371 km (the radius of the earth) is about 1 nautical mile (1 nautical mile is 1852 meters).
Or, I suppose, it's about 1770 meters for those who approximate pi as 3--which is the same as approximating 1MOA at 100 yards as 1".
"1" is the easiest number.
I use it so it doesn't feel lonely.
https://www.youtube.com/watch?v=22QYriWAF-U
I use it so it doesn't feel lonely.
https://www.youtube.com/watch?v=22QYriWAF-U
Jim Watson
New member
I thought it would be interesting to know what a sight maker did, so I took apart a scope sight and calibrated at the adjustments.
Well, really I didn't, I looked at the catalog specifications for Unertl outside adjusting target scope mounts.
The mount moves .0005" per click and the recommended ring spacing is 7.2" which said to be is 1/4" at 100 yards. And the arithmetic works out that way.
If you want 1/4 MOA, just space the rings at 6.88".
We have an excursion to a friend's 600 yard range coming up.
I'll be looking for the .28" difference between an IPHY and a MOA.
And oh, dear, what will we do if his survey was a little off?
Which is where the reductio ad adsurdem arguments fail. We aren't talking about miles, we are working in inches, even fractional inches on a target and the difference is trivial.
Well, really I didn't, I looked at the catalog specifications for Unertl outside adjusting target scope mounts.
The mount moves .0005" per click and the recommended ring spacing is 7.2" which said to be is 1/4" at 100 yards. And the arithmetic works out that way.
If you want 1/4 MOA, just space the rings at 6.88".
We have an excursion to a friend's 600 yard range coming up.
I'll be looking for the .28" difference between an IPHY and a MOA.
And oh, dear, what will we do if his survey was a little off?
Which is where the reductio ad adsurdem arguments fail. We aren't talking about miles, we are working in inches, even fractional inches on a target and the difference is trivial.
Jim Watson
New member
Right. The sight radius on a Sharps with tang sight is usually assumed to be at or near 36" which makes the 1/100" vernier graduations a "shooter's minute."
Don Fischer
New member
Easy formula for figuring what you want. Zero your rifle at 100 yds then set target's up from zero to 99 yds and shoot them and see where your at! Why make this difficult?