Scope Accuracy

[muleman1953]

Need Expert Advice!
Hope this belongs here?
I checked my true dial up at 100 yds, measured with a steel tape for Accuracy. When I dialed my Nightforce up 30 MOA it truly move 32.25" with the gun locked in a vice for absolutely no movement. I repeated this 3 times & everytime I moved from 0 to 30 MOA or back to 0 it moved at 100 yds on a Steel tape 32.25".
Now if 1 MOA is 1.047" at exactly 100 yds and I take 30"X 1.047"=31.41". So shouldn't my Scope have only truly moved 31.41" instead of the 32.25"?
My question is on Ballistics Program they have a Elevation Correction Factor, Is this where you make the correction if your scope is off like this?
Would you divide the 32.25 by 31.41 which = 1.0267?
Is this what you'd substitute instead of 1 in the Elevation Correction Factor in the program?
Hope I made sense.
Thank You,
Wayne

 

[sourdough44]

This seems like a question to email Nightforce about. My next thought is just trying the dial adjustments at a range, after the scope is properly sighted it.

There are so many little factors in the mix. One biggie being the particular ballistics of the ammo then the characteristics of the bullet fired. I saw a guy once doing just great at the skeet range with his Model 870 shotgun. Very little takes the place of quality range time.

 

[jmason]

that looks correct.

 

[muleman1953]

After some research on this it looks like I should be below 1 for a correction factor in the program, as it is moveing (32.25') more than the correct dialup(31.41).
I think I should have divided 31.41" by 32.25"= .947 Correction factor.
I've checked 4 other scopes & non of them were dead on, one was worse than this one. I know it doesn't matter much on this until you start getting past 1200-1500yds then it makes a difference on your true dialup, & that's where I'm going with this.
Any info on this topic is much appreciated, I've got lots to learn!
Wayne

 

[bill123]

After some research on this it looks like I should be below 1 for a correction factor in the program, as it is moveing (32.25') more than the correct dialup(31.41).
I think I should have divided 31.41" by 32.25"= .947 Correction factor.
I've checked 4 other scopes & non of them were dead on, one was worse than this one. I know it doesn't matter much on this until you start getting past 1200-1500yds then it makes a difference on your true dialup, & that's where I'm going with this.
Any info on this topic is much appreciated, I've got lots to learn!
Wayne

From the instructions for the "Shooter" app:
"Elevation Correction - This is used to correct for scope turret clicks that aren't quite what they say they are. If you've come to realize your .25MOA per-click scope is actually .23MOA per-click then you'd put a correction factor of 1.08695652 (.25/.23) because you actually need to adjust more as you aren't quite getting a full quarter MOA per click. So say your elevation solution for a 1000yd shot is 28MOA and you have the correction factor of 1.08695652. Shooter will multiply 28 by 1.08695652 to give you 30.4MOA. So even though the real solution is 28, you'd dial 30.4MOA because your scope only adjusts .23MOA rather than .25MOA per-click. An asterisk (*) will be placed next to the angular unit in the Solution and Trajectory Table screens when using these inputs to denote that the given value is corrected and not the actual calculated correction. Inaccurate click adjustments are more common than you may think. Don't take this for granted. To effectively disable this feature, leave the input set to 1.0"

Unfortunately the formula may be based on how the app converts your number. See the description of how Ballistic AE handles the conversion:
Elevation / Windage Turret Value: Some scopes are not exact; that is, one click does not necessarily equal exactly one MOA or one Mil. If you know the actual click value of your scope turrets (for example .982), you can enter it here. The output units (regardless of whether they're MOA, mRad, or anything else) will automatically be divided by this value, to give you an accurate number of clicks. For example, if your turret value is 1/3 of a click and your output is 5 MOA, then enter .333 in this field. The output will read 15.01 (5 / .333). NOTE: Versions < 4.7 multiply this value, rather than divide it. Division is the correct way to compensate for turret correction, so if you're using an older version below 4.7, you'd enter 3.333 instead of .333.

I think that the best solution for you is to do the computation using both division and multiplication and run the conversion in the app that you are using. Only one number will make sense.

As for how much error is acceptable, Bryan Litz in his video "Putting Rounds on Target" says that an error of 1% or less is acceptable.

 

[muleman1953]

Bill,
Thanks, That's Exactly what I was looking for!!!