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Tech. Question on MOA Calcs.

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Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: July/09/2007 at 18:04
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Suppose i'm using a plex reticle that subtends 5.0 MOA to the lower post tip from center x-hair. If a certain zero at a certain range is 2.5 MOA will that zero be referenced dead center between the x-hair and post tip, or is it skewed slightly due to the nonlinear nature of angular measurements??

 

I'm assuming it would not be dead center since rangefinding with reticles is nonlinear also.

Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: July/09/2007 at 22:51
Dale Clifford View Drop Down
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it will at that mag, and load. the skewness will only increase or decrease as the ln(x) changes with increase or decrease of magnification. the drop say from adding 300 yds more to the distance will still be referenced by the zero. and the hold over or hold down will still be the same ln curve.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: July/10/2007 at 16:29
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Thks. Dale.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: July/10/2007 at 20:48
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Originally posted by Dale Clifford Dale Clifford wrote:

it will at that mag, and load. the skewness will only increase or decrease as the ln(x) changes with increase or decrease of magnification. the drop say from adding 300 yds more to the distance will still be referenced by the zero. and the hold over or hold down will still be the same ln curve.


I am a little confused here.  ln(x)? what exactly are you referring to? what is "x" in this case?

ILya
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: July/11/2007 at 12:48
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The reason that i ask this question is that rangefinding is not linear, since angular measurements are nonlinear. It's supposed to be a trigonometric function. A mil-dot reticle subtends 3.6" @ 100 yds., and 7.2" @ 200 yds., but does it also subtend exactly 5.4" @ 150 yds.? I don't think it does. If u use that mil-dot for rangefinding, and the object ranges @ 100 yds, then it will gap .5 of that subtension @ 200 yds., but if it gaps .75 that subtension it is not exactly 150 yds. away, it is more like 130 yds.

 

If my assumption is correct then if a particular ballistic reticle's stadia is set up to have one zero @ say 100 yds. and the next stadia is 200 yds. then 150 yds. is a little closer to the 2nd stadia than 2.5. It would be something like 2.6, or maybe .7.

 

This effect may be negated by the parabolic nature of trajectories, since the "50" yd. mark (in the example above) would then conversely be closer than the .5 mark.

 

This is just theoretical stuff that i was wondering about, and didn't know where else to pose these questions.

Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: July/11/2007 at 16:20
Dale Clifford View Drop Down
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The reason that i ask this question is that rangefinding is not linear, since angular measurements are nonlinear. ,

 

 

angular measurement are linear, there are no higher order terms in the expression to give them any more degrees of freedom than linear, trig. fun, and polar co-ordinates are just another way to express cartesian coordinates. the mill does subtend 5.4 by definition.

 

its not theoretical its just "math" stuff

 

trajectories follow a natural decay curve (ln against some set of distance pts. say (x))compensating systems don't work in the same way as mil dot. the "progressive" scale used becomes calibrated to the some point in space that matches the points in 2 dimensions of the actual path.

the weakness in the arguement comes from the statistical nature of the trajectory, which depends on data from that shot, but if the discussion is started with an exact set of numbers for this then the stadia marks on the cross hair will co-incide with the bullet path.

 

if the first stadia wire is set for 100 yds and the second by definition at 200, the 150 "marker" would be closer to the first stadia wire, but proably less than a thickness of stadia wire.  as it follows the data determined by traj

 

"This effect may be negated by the parabolic nature of trajectories, since the "50" yd. mark (in the example above) would then conversely be closer than the .5 mark."  this does occur in mil-dotting. and why the dial in would be x+some constant and also the advantage of a compensating device--theoretically

Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: July/11/2007 at 18:17
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Thks. Dale--I understood most of it.
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