ROLEXrifleman
Master
The mechanical center of a scope is the point at which both the windadge and elevation turrets have an equal amount of adjustment to each side.
Most don’t give this much thought as all they do is mount a scope, zero it in at a particular distance and never give it any thought after that yet it is very important for several reasons.
1) You may not always get the windage and elevation you pay for!
2) Knowing what adjustment you have used and what you have left will allow you to hit your mark at different ranges
3) Knowing your adjustments will allow you to buy proper mounts for the right reasons
Knowing exactly what adjustment you have will allow you to understand whether or not a particular scope will be sufficient for the application at hand. For the most part any scope with a decent build quality will get you zeroed at 100yards with no problem. If you never plan on using it past 100yards then this tutorial might as well be over. Some of you though may have encountered the fact that your scope would not zero at 100 yards and you were several inches away from the X, a good case for not enough adjustment and or bad mount options. In addition it seems many talk the game about shooting at extreme distances yet fool themselves as they will never get to a range that is beyond 300 yards or really have no desire to shoot extreme distances. Either way I hope this tutorial helps the masses understand how every choice you make in your build directly effect the end result. Furthermore, to make the proper choices you need to be not only honest with yourself about the end results expected of your build but realistic in your expectations of the equipment you choose. With that said lets get started.
To find the mechanical center of your scope you 1st need to bottom out one of the two turrets. For our example we will start with the elevation turret. Spin the turret in one direction till you can no longer go any more. Don’t force it, but you will feel a definite stop. From this point you will spin the turret one click at a time in the other direction until you feel the same stop. Keep in mind the number of clicks you completed in order to get to this point as this will be the TOTAL amount of elevation your scope has.
In addition to this you will also see how well the turret turns, how much effort is needed and how consistent or inconsistent the effort is needed to make the turns. Build quality is generally the number one issue of the movement of a turret. Similar to the comparison of a made in china watch movement or a Rolex watch movement, although they both may tell time there is a difference.
Back to the elevation turret. You now take this TOTAL number and divide it by the unit of measure on your turret, this will give you the TOTAL amount of elevation in whatever measure the scope is set up for. For example:
You count 123 clicks from one end to the other, your turrets are rated at .25MOA clicks, we know that .25 is equal to ¼ MOA so we divide
124 / 4 = 31 MOA
We now know that we have a TOTAL amount of 31 MOA of usable elevation. We now go back to the scope and CENTER the elevation turret. To do so you divide the total number of clicks by 2.
124 / 2 = 62. We now know we must turn 62 clicks from the stop in the scope we are at to get the ELEVEATION turret into center. After this is accomplished we now know that we have 15.5 MOA of elevation in either the UP or Down direction.
62 (number of clicks we moved) / 4 ( what we know as the increment of measure from our scope) = 15.5 ( one half the total of the scope’s internal elevation travel)
We then do the same for the ELEVATION turret.
When this is complete your scope will be in its MECHANICAL center. It is a reference point that will begin to give you a wealth of knowledge if you know what your needs are out of a particular set up.
Now some REAL WORLD examples. I have 2 NF NXS scopes. The 1st a 12-42 the second an 8-32. Both .25 MOA turrets. NF lists the specs for the scopes as follows:
NXS 12 -42
Elevation = 45MOA
Windage 35 = MOA
NXS 8 – 32
Elevation = 65MOA
Windage = 45MOA
On the 12 -42 here are the ACTUAL measurements I obtained.
Elevation = 190 clicks / 4 = 47.5 MOA 2.75 MOA more movement than listed in specs
Windage = 128 clicks / 4 = 32.0MOA 3.0 MOA less than listed
On the 8 -32 here are the ACTUAL measurements I obtained.
Windage = 246 clicks / 4 = 61.5MOA 3.5 MOA LESS than listed
Elevation = 174 clicks / 4 = 43.5MOA 1.5 MOA LESS than listed
So as you can see, even some “higher” end scopes don’t always give you what you pay for. Starting with a base line will give you good insight as to what direction you should be taking your build or what direction your build will be taking you if you don’t make changes.
Based on the ACTUAL findings of both of these scopes and knowing that I will be using them on .308 rifles I already know that without some type of mount with adjustment already built in neither of these scopes will get me to 1K yards on their own. This is an entire topic that will be covered later.
Keep the 12 -42 scope in mind as this will be a key factor in a series of threads that I will be making documenting the “birth” of a tack driver: from the drawing board to the shooting bench. How doing the math at home should equate to your performance at the bench and how “real world” throws all the numbers off….. Or does it?
Stay tuned
Most don’t give this much thought as all they do is mount a scope, zero it in at a particular distance and never give it any thought after that yet it is very important for several reasons.
1) You may not always get the windage and elevation you pay for!
2) Knowing what adjustment you have used and what you have left will allow you to hit your mark at different ranges
3) Knowing your adjustments will allow you to buy proper mounts for the right reasons
Knowing exactly what adjustment you have will allow you to understand whether or not a particular scope will be sufficient for the application at hand. For the most part any scope with a decent build quality will get you zeroed at 100yards with no problem. If you never plan on using it past 100yards then this tutorial might as well be over. Some of you though may have encountered the fact that your scope would not zero at 100 yards and you were several inches away from the X, a good case for not enough adjustment and or bad mount options. In addition it seems many talk the game about shooting at extreme distances yet fool themselves as they will never get to a range that is beyond 300 yards or really have no desire to shoot extreme distances. Either way I hope this tutorial helps the masses understand how every choice you make in your build directly effect the end result. Furthermore, to make the proper choices you need to be not only honest with yourself about the end results expected of your build but realistic in your expectations of the equipment you choose. With that said lets get started.
To find the mechanical center of your scope you 1st need to bottom out one of the two turrets. For our example we will start with the elevation turret. Spin the turret in one direction till you can no longer go any more. Don’t force it, but you will feel a definite stop. From this point you will spin the turret one click at a time in the other direction until you feel the same stop. Keep in mind the number of clicks you completed in order to get to this point as this will be the TOTAL amount of elevation your scope has.
In addition to this you will also see how well the turret turns, how much effort is needed and how consistent or inconsistent the effort is needed to make the turns. Build quality is generally the number one issue of the movement of a turret. Similar to the comparison of a made in china watch movement or a Rolex watch movement, although they both may tell time there is a difference.
Back to the elevation turret. You now take this TOTAL number and divide it by the unit of measure on your turret, this will give you the TOTAL amount of elevation in whatever measure the scope is set up for. For example:
You count 123 clicks from one end to the other, your turrets are rated at .25MOA clicks, we know that .25 is equal to ¼ MOA so we divide
124 / 4 = 31 MOA
We now know that we have a TOTAL amount of 31 MOA of usable elevation. We now go back to the scope and CENTER the elevation turret. To do so you divide the total number of clicks by 2.
124 / 2 = 62. We now know we must turn 62 clicks from the stop in the scope we are at to get the ELEVEATION turret into center. After this is accomplished we now know that we have 15.5 MOA of elevation in either the UP or Down direction.
62 (number of clicks we moved) / 4 ( what we know as the increment of measure from our scope) = 15.5 ( one half the total of the scope’s internal elevation travel)
We then do the same for the ELEVATION turret.
When this is complete your scope will be in its MECHANICAL center. It is a reference point that will begin to give you a wealth of knowledge if you know what your needs are out of a particular set up.
Now some REAL WORLD examples. I have 2 NF NXS scopes. The 1st a 12-42 the second an 8-32. Both .25 MOA turrets. NF lists the specs for the scopes as follows:
NXS 12 -42
Elevation = 45MOA
Windage 35 = MOA
NXS 8 – 32
Elevation = 65MOA
Windage = 45MOA
On the 12 -42 here are the ACTUAL measurements I obtained.
Elevation = 190 clicks / 4 = 47.5 MOA 2.75 MOA more movement than listed in specs
Windage = 128 clicks / 4 = 32.0MOA 3.0 MOA less than listed
On the 8 -32 here are the ACTUAL measurements I obtained.
Windage = 246 clicks / 4 = 61.5MOA 3.5 MOA LESS than listed
Elevation = 174 clicks / 4 = 43.5MOA 1.5 MOA LESS than listed
So as you can see, even some “higher” end scopes don’t always give you what you pay for. Starting with a base line will give you good insight as to what direction you should be taking your build or what direction your build will be taking you if you don’t make changes.
Based on the ACTUAL findings of both of these scopes and knowing that I will be using them on .308 rifles I already know that without some type of mount with adjustment already built in neither of these scopes will get me to 1K yards on their own. This is an entire topic that will be covered later.
Keep the 12 -42 scope in mind as this will be a key factor in a series of threads that I will be making documenting the “birth” of a tack driver: from the drawing board to the shooting bench. How doing the math at home should equate to your performance at the bench and how “real world” throws all the numbers off….. Or does it?
Stay tuned
