Scope Tracking

Discussion in 'Long Range Scopes and Other Optics' started by brianwy77, Oct 27, 2013.

  1. brianwy77

    brianwy77 Member

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    What is the best way to check the tracking on a scope? I have a Vortex Viper FFP and I am not sure about the tracking.
     
  2. rcairflr

    rcairflr Well-Known Member

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    Shoot a square box. If you are at 100 yards, get it zeroed in, then left 2 MOA and up 2 MOA (upper left corner of the box). Then right 4 MOA (upper right corner of the box), then down 4 MOA (lower right corner of box), then left 4 MOA (lower left corner of box), then up 2 MOA and right 2 MOA to put you back in the bullseye.

    You can add or subtract MOA to make the box whatever size you want.
     

  3. bill123

    bill123 Well-Known Member

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    Also google "Tall Target Test" to check for % of turret error.
     
  4. kcebcj

    kcebcj Well-Known Member

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    When checking tracking or accuracy on any scope make certain you are at exactly 100 yards. It does not take much to screw it all up.
     
  5. cummins cowboy

    cummins cowboy Well-Known Member

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    its hard to test a scope this way because there are so many factors. I also think it takes a very very accurate rifle to expose problems. It took me quite a while to figure out how terrible my leupold was. I have never owned anything that tracks as well as my nightforce. I would be most worried about how the scope returns to zero, then how it performs in the field after cranking the turrets.
     
  6. Scot E

    Scot E Well-Known Member

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    I personally don't test scope tracking by shooting. It simply introduces too many variables that make finding real error very difficult. The naysayers to this say that you need to know what a scope does under recoil but in my experience on every scope I have tested if there is a recoil issue when shooting with a scope it will show up early and be something you can't get past.

    I instead put my gun in a sturdy gun vice where I can tighten it down so it doesn't move. I then measure out an exact distance with a tape measure and put up some test sheets that have MOA, Inch, and MIL measurements on them.

    A lot of guys do this at 100 yards and there are some advantages to this but the test can be ran at shorter distances which I have a tendency to like better if I can get the scope parallax to adjust to those close distances. The closer the test target is the better most guys can resolve the difference between the reticle and the measurement lines. Also, most guys have don't have tapes that measure 100 yards but can much more easily do half or quarter this distance and be very accurate in their measurements.

    Don't try to measure 1 MOA or 1 MIL but instead run the scope up a bit and average out the difference. If you suspect there are areas in your total adjustment travel that are worse than others, for instance the extremes of the adjustment travel, then those can be tested separately later as well. I run the test a few times to make sure I am getting an accurate measurement.

    Scot E.
     
  7. bruce_ventura

    bruce_ventura Well-Known Member

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    ^^^This!

    Calibrating turrets using the "shooting the box" method seems like a waste of good ammunition too me. Getting good accuracy requires 3-5 shots per reticle position, which adds up to a box of ammunition.

    Scott E's method is much more accurate and costs nothing. If you can set it up easily, then it's a much better method.

    Having to hold the rifle in a vise and sight a calibration target is inconvenient for me, however. I prefer to use a Bushnell boresight collimator to calibrate turrets. That requires that the collimator be calibrated, which is an extra step, but I can do the entire process indoors using almost anything to hold the rifle.

    Turret hysteresis or failure to track smoothly can also be diagnosed using the boresight collimator. Even failure to hold point of aim often can be debugged using a boresight collimator when the stock is the culprit.
     
  8. Scot E

    Scot E Well-Known Member

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    good Info. I was going to mention the collimator but the one I have is an old one and I am not up on which ones are good today. Which do you use, the magnetic one and how is the etched glass setup?

    Thanks,

    Scot E.
     
  9. bruce_ventura

    bruce_ventura Well-Known Member

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    I guess my favorite collimator is the Bushnell Professional Boresighter 74-3333. It provides three adjustable arbors that grab the bore when tightened. They are accurate to within about +/4 MOA, which is OK for most purposes. This model has an etched reticle with a 10x10 grid of 4 IPHY boxes, similar to many other models. The reticle pattern needs to be calibrated, usually by measuring the grid using a mildot reticle scope that you trust. They sure make reticle measurements easy, though. They have a dozen other uses as well.

    This Bushnell model also has a removable cap on the back end that allows the instrument to be calibrated if it falls out of cal (usually because someone fiddled with it). Nearly the entire country is out of stock right now waiting for the Bushnell to make more. You can find used ones on eBay.

    The magnetic collimators are not very accurate, but are needed for muzzle brakes. I made my own magnetic attachment that is as accurate as the muzzle brake it's attached to.

    All the other models from Bushnell, BSA, Simmons, etc., provide caliber-specific spuds that are too small. They fit the bore loosely and are not repeatable.

    Alley Supply sells the best bore spuds - very precise fitting - and they can be used with any collimator. The Alley Supply collimators are well made but they do not offer a grid pattern.

    I've been developing a new collimator that I hope to put into production soon. I'm working on manufacturing issues right now. The prototypes have been working great.
     
  10. Greyfox

    Greyfox Well-Known Member

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    I have also used the Bushnell/Cabelas grid collimators for quite some time. It works very well. In addition to testing turret movement, it can also be used to test vertical alignment(plumb) of the reticle through a 20-30 MOA elevation range, reticle aligment with the bore, attach the scope level, and insure everything is aligned. Good levels have to be used on the rifle rails and scope, and a secure rifle vice to do this. I will always do a tall target test at 100 yards when initially zeroing the rifle, to confirm actual click value, and plumb of the reticle. I have rarely, if ever had to realign the scope using this approach. I have found a couple of scopes over the years that had faulty tracking without firing a shot. You can also recheck scope tracking and alignment after a scope/rifle was subjected to a severe shock from a fall or other mishap.
     
  11. bruce_ventura

    bruce_ventura Well-Known Member

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    Correction. It has a 20x20 grid of 4 IPHY boxes. There is a cross hair running through the middle of the grid. This a standard reticle pattern that most boresight collimators have.
     

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