Speed centering a scope

Discussion in 'Firearm Maintenance, Modification, Safety And Trou' started by Rob poston, May 3, 2017.

  1. Rob poston

    Rob poston .270 WIN

    What brought me here?:
    Recently, a friend of mine brought me his rifle and scope to mount, and when he saw me pull out a mirror, he asked what I was doing. I explained to him that I use it as a way to center the scope before mounting, in order to maximize adjustment range. This got me thinking, maybe I should post on here, in case any of you could benefit.

    Why center a scope?:
    Well, the answer is fairly simple, when you think about it. All scopes have at least two adjustments- vertical (elevation), and horizontal (windage). Let's say your scope has 300 clicks of adjustment on each. A properly centered scope will place the reticle at 150 clicks in and down. If you are either high or low from center, you will decrease your windage adjustability as well. Likewise, if you are left or right of center, you will reduce your adjustability on elevation. Picture drawing a circle on a piece of grid paper, and you will easily understand why this occurs. The longest lines are the middle vertical and middle horizontal. Additionally, if you are off center by 50 clicks, you can only adjust an additional 100 clicks in that direction. All in all, you always want to start out with a proper foundation before moving forward, and centering the scope is an important, and often overlooked aspect of scope mounting.

    The old way of doing things?:
    Now let's discuss the old way of centering. First, you bring the scope all the way to one side, then you take it all the way to the other side, counting the clicks. Again, let's assume there are 300 clicks, for this scenario. Then, you count back 150 clicks, to center. Repeat this process with the elevation, to find the center of it, as well.

    What's wrong with the old method?:
    Problem is, that I have better things to do, than to count 300 clicks, 150 clicks, 300 clicks, and 150 clicks (900 total), and knowing my luck, the phone will ring on click #299 each time. ;-) Also, I am not a fan of running a scope all the way out on each bank... it can put unnecessary stress on the scope.

    The alternative way to center:
    So here is the alternative... use a simple mirror. Simply place the objective lens of the scope (large "bell" directly against a mirror. Now look into the scope as you normally would. You will see either one, or two sets of crosshairs. If you see one, stop. You are perfectly centered. If you see two, simply make a few quick adjustments so that the reflection of the crosshairs lines up directly behind the actual crosshair. Once you see just one reticle, you are perfectly centered. Now, you can move on to properly mounting the scope to the rifle, bore sight the weapon system, take it to the range, and zero the rifle in.

    2-bullet zeroing:
    Place the rifle on a shooting bench or rest. Sight in on the target, and fire a round. Without moving the weapon, adjust the reticle so that you zero in on the bullet hole. Readjust the rifle to the bullseye, and see how you did. You should be dialed in now.
    Last edited: May 3, 2017
  2. SHOOTER13

    SHOOTER13 Guest

    Thread moved from Politics/Firearm Related to the correct sub forum.
    Rob poston likes this.
  3. Rob poston

    Rob poston .270 WIN

    Whoops! I just noticed that I put it in the wrong section. Sorry about that, and thanks for moving it for me, Shooter!
    SHOOTER13 likes this.
  4. SHOOTER13

    SHOOTER13 Guest

    No problem Rob...

    That's why I make the big bucks.
    Rob poston likes this.

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