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Range Report Formula; convert inches to MOA?
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Re: Formula; convert inches to MOA?
If you mean inches of drop, for example, it's just this:
<div class="ubbcode-block"><div class="ubbcode-header">Code:</div><div class="ubbcode-body ubbcode-pre" ><pre>
inches * 100
MOA = --------------------------
1.047 * distance in yards
</pre></div></div>
If you mean inches of drop, for example, it's just this:
<div class="ubbcode-block"><div class="ubbcode-header">Code:</div><div class="ubbcode-body ubbcode-pre" ><pre>
inches * 100
MOA = --------------------------
1.047 * distance in yards
</pre></div></div>
Re: Formula; convert inches to MOA?
IMHO, an inch is equivalent to an MOA, close enough. I seriously doubt I could hold to within 0.47" at 1000yd anyway...
IMHO, an inch is equivalent to an MOA, close enough. I seriously doubt I could hold to within 0.47" at 1000yd anyway...
Re: Formula; convert inches to MOA?
Greg: assume that you have a scope calibrated in inches per hundred yards rather than MOA.
Assume that the drop of your .308 at 1000 yards is 400 inches.
Using the calculation above, the elevation you'd crank on your scope is 38.2.
If you assume an MOA is an inch, you'd use 40.
The difference, 1.8 MOA, at 1000 yards, is 18.85 inches - which is a big miss on most targets.
So, your assumption is flawed - except at very short distances.
Greg: assume that you have a scope calibrated in inches per hundred yards rather than MOA.
Assume that the drop of your .308 at 1000 yards is 400 inches.
Using the calculation above, the elevation you'd crank on your scope is 38.2.
If you assume an MOA is an inch, you'd use 40.
The difference, 1.8 MOA, at 1000 yards, is 18.85 inches - which is a big miss on most targets.
So, your assumption is flawed - except at very short distances.
Re: Formula; convert inches to MOA?
As a quick rule of thumb, just round it up to a 5% difference and see what the magnitude of error is. 10 "inches MOA" at 100 yards about equals 9.5 true MOA, or 10 MOA roughly equals 10.5 inches. So, two clicks per 10 MOA is what we're dealing with.
As a quick rule of thumb, just round it up to a 5% difference and see what the magnitude of error is. 10 "inches MOA" at 100 yards about equals 9.5 true MOA, or 10 MOA roughly equals 10.5 inches. So, two clicks per 10 MOA is what we're dealing with.
Re: Formula; convert inches to MOA?
I know this is going to sound kind of silly, but does 1" still equal 1 MOA at 100 meters as well? since that is actually 109 yards? I know that MOA is a unit of angular measurement, but it just seems kind of weird to be mixing SAE and Metric measurements like that if it is the case. A little help would be appreciated!
I know this is going to sound kind of silly, but does 1" still equal 1 MOA at 100 meters as well? since that is actually 109 yards? I know that MOA is a unit of angular measurement, but it just seems kind of weird to be mixing SAE and Metric measurements like that if it is the case. A little help would be appreciated!
Re: Formula; convert inches to MOA?
One inch does not equal 1 MOA at 100 yards. It does not equal one MOA at 100 meters, either.
One MOA is an angle which subtends an arc whose length is 1.047 inches at 100 yards. At 100 meters, is subtends an arc whose length is about 1.145 inches.
One inch does not equal 1 MOA at 100 yards. It does not equal one MOA at 100 meters, either.
One MOA is an angle which subtends an arc whose length is 1.047 inches at 100 yards. At 100 meters, is subtends an arc whose length is about 1.145 inches.
Re: Formula; convert inches to MOA?
1 moa equals an inch at 95.5 yards I think.
1 moa equals an inch at 95.5 yards I think.
Re: Formula; convert inches to MOA?
Yes.
To know approximately what one MOA measures at any distance, just multiply the distance times the tangent of the angle.
If you're working in degrees, multiply the distance times the tangent of 1/60th of a degree.
Yes.
To know approximately what one MOA measures at any distance, just multiply the distance times the tangent of the angle.
If you're working in degrees, multiply the distance times the tangent of 1/60th of a degree.
Re: Formula; convert inches to MOA?
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Lindy</div><div class="ubbcode-body">One inch does not equal 1 MOA at 100 yards. It does not equal one MOA at 100 meters, either.
One MOA is an angle which subtends an arc whose length is 1.047 inches at 100 yards. At 100 meters, is subtends an arc whose length is about 1.145 inches.
</div></div>
Thanks! I had a feeling that was the case, just wasn't sure of the math to back it up.
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Lindy</div><div class="ubbcode-body">One inch does not equal 1 MOA at 100 yards. It does not equal one MOA at 100 meters, either.
One MOA is an angle which subtends an arc whose length is 1.047 inches at 100 yards. At 100 meters, is subtends an arc whose length is about 1.145 inches.
</div></div>
Thanks! I had a feeling that was the case, just wasn't sure of the math to back it up.
Re: Formula; convert inches to MOA?
40MOA x .047" fudge factor = 1.88". Like I said, not a big issue. Your logic is OK, your arithmetic needs some work; please check your decimals. The assumption is not flawed. If you can hold to either .47" or 1.88" at 1000yd, my hat is off to you.
Greg
40MOA x .047" fudge factor = 1.88". Like I said, not a big issue. Your logic is OK, your arithmetic needs some work; please check your decimals. The assumption is not flawed. If you can hold to either .47" or 1.88" at 1000yd, my hat is off to you.
Greg
Re: Formula; convert inches to MOA?
Greg: You almost got the math correct. The fudge factor is not 1.88 <span style="font-style: italic">inches</span> but 1.88 <span style="font-weight: bold">MOA</span>.
And 1.88 MOA at 1000 yards is 19.68 inches.
I discovered that distinction when I switched from a Leupold 3.5-10X40M2 to a 6.5-20X50M1. My elevation at 1000 yards suddenly changed by 2 MOA. Checking the scopes, I found the M3 adjustments were true MOA, and the M1 adjustments were IPHY.
And that's why it matters.
Greg: You almost got the math correct. The fudge factor is not 1.88 <span style="font-style: italic">inches</span> but 1.88 <span style="font-weight: bold">MOA</span>.
And 1.88 MOA at 1000 yards is 19.68 inches.
I discovered that distinction when I switched from a Leupold 3.5-10X40M2 to a 6.5-20X50M1. My elevation at 1000 yards suddenly changed by 2 MOA. Checking the scopes, I found the M3 adjustments were true MOA, and the M1 adjustments were IPHY.
And that's why it matters.
Re: Formula; convert inches to MOA?
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Greg Langelius *</div><div class="ubbcode-body">40MOA x .047" fudge factor = 1.88". Like I said, not a big issue. Your logic is OK, your arithmetic needs some work; please check your decimals. The assumption is not flawed. If you can hold to either .47" or 1.88" at 1000yd, my hat is off to you.
Greg</div></div>
No issue at all when it's just about adjusting for a prevailing wind at a distance for which a good no-wind zero has been already been established. It's a bigger issue as Lindy makes clear when plugging in one unit of measure for another when adjusting to a new zero distance.
In the example of going from a 100 yard zero to a 1000 yard zero, where to get line of sight and bullet path to intersect at 1000 yards, a bullet path above line of sight at 100 yards would be, let's say, about 40 inches, substituting MOA for inches would actually get the bullet about 19 inches high at 1000 yards. This would place the bullet somewhere at 12 o'clock in the 8 or 7 ring.
Of course, it's always good to know the value of your clicks whatever the unit of measure.
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Greg Langelius *</div><div class="ubbcode-body">40MOA x .047" fudge factor = 1.88". Like I said, not a big issue. Your logic is OK, your arithmetic needs some work; please check your decimals. The assumption is not flawed. If you can hold to either .47" or 1.88" at 1000yd, my hat is off to you.
Greg</div></div>
No issue at all when it's just about adjusting for a prevailing wind at a distance for which a good no-wind zero has been already been established. It's a bigger issue as Lindy makes clear when plugging in one unit of measure for another when adjusting to a new zero distance.
In the example of going from a 100 yard zero to a 1000 yard zero, where to get line of sight and bullet path to intersect at 1000 yards, a bullet path above line of sight at 100 yards would be, let's say, about 40 inches, substituting MOA for inches would actually get the bullet about 19 inches high at 1000 yards. This would place the bullet somewhere at 12 o'clock in the 8 or 7 ring.
Of course, it's always good to know the value of your clicks whatever the unit of measure.
Re: Formula; convert inches to MOA?
<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">Of course, it's always good to know the value of your clicks whatever the unit of measure.</div></div>
Absolutely essential. I have three older Leupold scopes with M1 adjustments. All are IPHY, yet I have people who have tested more recent models who say they have M1 scopes with true MOA adjustments.
In any case, I think it's essential to test every individual scope to see what it's adjustments are, and also whether they are linear.
<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">Of course, it's always good to know the value of your clicks whatever the unit of measure.</div></div>
Absolutely essential. I have three older Leupold scopes with M1 adjustments. All are IPHY, yet I have people who have tested more recent models who say they have M1 scopes with true MOA adjustments.
In any case, I think it's essential to test every individual scope to see what it's adjustments are, and also whether they are linear.
Re: Formula; convert inches to MOA?
http://www.calguns.net/calgunforum/showthread.php?t=154758
http://www.calguns.net/calgunforum/showthread.php?t=199178
http://www.calguns.net/calgunforum/showthread.php?t=154758
http://www.calguns.net/calgunforum/showthread.php?t=199178
Re: Formula; convert inches to MOA?
Aside from the fact that the first post in the first thread has the common error about there being a difference between Army and Marine mils, was there a point you were trying to make in posting those links?
Aside from the fact that the first post in the first thread has the common error about there being a difference between Army and Marine mils, was there a point you were trying to make in posting those links?
Re: Formula; convert inches to MOA?
My apologies, my decimal is, as you say, wrong.
It amounts to about 5% per MOA.
I keep forgetting about the CCB-only, one shot, one kill concept. You guys bank on single shots, my discipline (FV200) works with mainly sustained fire, two quite different animals. In a match, I'll shoot 40 for score, and anywhere from 5-10 sighter/foulers, spread out over two separate stages and four scoring bulls.
I shoot Highpower, F Class, (actually a 200yd club match offshoot we are developing, we call it FV200) and being off by 1.968" vertical at 100yd, 3.936" at 200yd is not a terrible error for an initial, calc-only ranging shot. I would still be, at worst, a 9. Starting with a CCB, I wouldn't even be adjusting the sights for another shot or two, until the rifle fouls, heats up some, and settles in.
At 1000yd, with an 800-1000yd target, such a 19.68" miss would very likely still be on paper, actually, in the 8 ring, and quite honestly, better than most first ranging shots I have seen in F Class, myself most definitely included. (2.5" off cuts the X ring, 5" off cuts the 10 ring, 10" off cuts the 9 ring, 20" off cuts the 8 ring, or thereabouts, the 8 may be a tad bigger; I'm not so certain that far from the X.). For irons and AROS, it would still be a 9.
Many, maybe most, need a spotter to call dust puffs 4-8ft from the center-x on their first (and sometimes a few subsequent) sighter shots first time out for the season.
Some venues insist on a 2 sighter limit. Thank goodness I (and probably most I shoot with) are not held to such a standard.
There's a goodly number of reasons why I don't do tactical comp.
Age and health not withstanding, the primary issue is that, honestly, I'm not the kind of UKD marksman it takes to be able to render such surgical precision marksmanship, first time, every time. I all too often forget that it's not only a different discipline, it's also a far more demanding one.
So my hat should be off, and to you folks who can actually do it, it is.
Greg
My apologies, my decimal is, as you say, wrong.
It amounts to about 5% per MOA.
I keep forgetting about the CCB-only, one shot, one kill concept. You guys bank on single shots, my discipline (FV200) works with mainly sustained fire, two quite different animals. In a match, I'll shoot 40 for score, and anywhere from 5-10 sighter/foulers, spread out over two separate stages and four scoring bulls.
I shoot Highpower, F Class, (actually a 200yd club match offshoot we are developing, we call it FV200) and being off by 1.968" vertical at 100yd, 3.936" at 200yd is not a terrible error for an initial, calc-only ranging shot. I would still be, at worst, a 9. Starting with a CCB, I wouldn't even be adjusting the sights for another shot or two, until the rifle fouls, heats up some, and settles in.
At 1000yd, with an 800-1000yd target, such a 19.68" miss would very likely still be on paper, actually, in the 8 ring, and quite honestly, better than most first ranging shots I have seen in F Class, myself most definitely included. (2.5" off cuts the X ring, 5" off cuts the 10 ring, 10" off cuts the 9 ring, 20" off cuts the 8 ring, or thereabouts, the 8 may be a tad bigger; I'm not so certain that far from the X.). For irons and AROS, it would still be a 9.
Many, maybe most, need a spotter to call dust puffs 4-8ft from the center-x on their first (and sometimes a few subsequent) sighter shots first time out for the season.
Some venues insist on a 2 sighter limit. Thank goodness I (and probably most I shoot with) are not held to such a standard.
There's a goodly number of reasons why I don't do tactical comp.
Age and health not withstanding, the primary issue is that, honestly, I'm not the kind of UKD marksman it takes to be able to render such surgical precision marksmanship, first time, every time. I all too often forget that it's not only a different discipline, it's also a far more demanding one.
So my hat should be off, and to you folks who can actually do it, it is.
Greg
