Math question on scope adjustment?

[RFears]

So on a 300 RUM with a 20" drop at 500, Dead on at three hundred, 1/4". 83 clicks should put me on right? Theory....

 

[Ridge Runner]

So on a 300 RUM with a 20" drop at 500, Dead on at three hundred, 1/4". 83 clicks should put me on right? Theory....

Not quite,
MOA (minute of angle) a unit of angular measurement equal to 1/60th of 1 degree or 1.0473" per 100 yards of range

so 1/4 MOA is 1.0473/4=.262"
at 500 yards 1/4 MOA is .262" (1/4 moa)X5 (range in hundreds of yards)=1.31 so each 1/4 MOA click on the scope will move point of impact 1.31" at 500 yards
20"/1.31=15.2 or 15 clicks
So say your shooting 820 yards your scope adjustment will move POI .262x8.2=2.15" per click
RR

 

[jimbires]

Can it happen that you are dead set even left/right at 100, then the further out, you are off one way or the other...what causes that?

here is a very good article that explains how to set up your scope . this could be your problem . Jim


Reticle Perpendicularity

 

[demented]

As a rule of thumb when getting a rifle/scope combo set for extended ranges, I set my POI to be one inch left to allow for bullet spin from a right hand twist. This is not perfect for all calibers or all rifles but it does keep me in the game.

 

[jwp475]

I believe that your scope adjusts in "Inches Per Hundred Yards" ( IPHY) and not I MOA (Minute Of Angle). 1/8 clicks adjusts the reticle .125 inches per click per hundred yards. A 1/8 MOA click adjusts the reticle .130 inches per hundred yards.

Just think in IPHY instead of MOA and you will have an easier time of it

 

[4xforfun]

Funny story,

A few years ago I got all anal about the whole inch/moa thing. I was not real sure about my Leupold scope.....did it move in inches or moa. I called Leupold for the answer. I talked to several people up the food chain and they all said the same thing...."MOA and inches mean the same thing". When I asked them if 30 MOA and 30 inches at 1000 yards is EXACTLY the same....they said....."YES.....EXATLY" !!!!!!


Go figure.

To this day I am not sure. How about NF Scopes.

Can anyone answer this....are the Leupold adjustments in MOA or inches? It looks like my NF is in MOA. I am pretty sure that the litierature from Leupold says inches, but are they just trying to simplify things? You know...the "they mean the same thing" speach they gave me because they don't think we are smart enough to comprehend the differance.

 

[BountyHunter]

Can it happen that you are dead set even left/right at 100, then the further out, you are off one way or the other...what causes that?

Yes, your scope is not perfectly perpendicular and you need to read the articles on this site about how to check that and confirm perfect vertical.

BH

 

[jwp475]

Can anyone answer this....are the Leupold adjustments in MOA or inches? It looks like my NF is in MOA. I am pretty sure that the litierature from Leupold says inches, but are they just trying to simplify things? You know...the "they mean the same thing" speach they gave me because they don't think we are smart enough to comprehend the differance.

Leupold scopes in my experience have all adjusted in Inches Per Hundred Yards (IPHY) not true MOA

All Nightforce scopes adjust in true MOA


Adjust a scope 30 IPHY and you have adjusted for 300 inches at 1,000 yards. Adjust 30 MOA and you have moved the point of impact 314.16 inches at 1,000 yards

There is definately a difference