Tall Target Test

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  • NugginFutz
    Chieftain
    • Aug 2013
    • 2622

    Tall Target Test

    Bryan Litz posted this video last week.

    Tall Target Test

    The video demonstrates a simple test which will determine if your scope accurately tracks vertically, and if it is mounted correctly.

    Didn't choose the perfect scope? No worries, there. He also shows how to easily apply corrections for scopes that don't track perfectly.

    I strongly encourage everyone who shoots long distance (or imagines they might) to view this - it is well worth the watch.


    As a side note, let me offer the following observation: I've had a few folks tell me that mounting a bubble level on one's scope is a waste of time, and that you should be able to eyeball scope level. Well, true as that sentiment may be for those individuals, I submit that it takes a LOT of practice to determine true level across any terrain. I don't shoot LR at varied locations enough to develop this skill set. Seeing how someone like Mr. Litz employed his level(s) just served to reinforce in my mind why that little $30 add-on is there. Any pilot will tell you that trusting your instruments is way more important than trusting the seat of your pants.
    If it's true that we are here to help others, then what exactly are the others here for?
  • rabiddawg
    Chieftain
    • Feb 2013
    • 1664

    #2
    Man, that is some good stuff!!

    Thanks for posting that!
    Knowing everthing isnt as important as knowing where to find it.

    Mark Twain

    http://www.65grendel.com/forum/showt...2-Yd-Whitetail

    Comment

    • Savage Shooter
      Warrior
      • Dec 2014
      • 241

      #3
      If you are into a bit of science behind the ballistics, I definitely recommend the full DVD series that this was taken from "Putting Rounds on Target". Also I agree with Brian's recommendation to actually measure the distance to the target using an old fashioned tape measure (I bought a 300 ft one sale for only $30) if you are going to try to determine the proper correction factor. One of the ranges where I prefer to do my OCW load work is 99' from the front of the bench on one end of the range and 97' on the other end of the row of benches, which is only 50 ' long. So the bench line is not parallel to the line of fixed holes in the ground which hold the target frames. I have a long range shooting class coming up and ironically need to go through these exact procedures to determine if my Vortex scopes are off.
      My "6.5" = 24" AA Overwatch upper 1/9 twist, NC based US Tactical lower, standard A4 6 position stock, AR Gold Trigger, JPS SCS buffer, Vortex 6-24 x 50 FFP PST with EBR-2C MOA reticle

      Comment

      • lrgrendel
        Warrior
        • Jul 2013
        • 662

        #4
        Really good info.
        Anyone know the formula for "mils"?

        Comment

        • Savage Shooter
          Warrior
          • Dec 2014
          • 241

          #5

          MILS and MOA
          A Guide to understanding what they are and
          How to derive the Range Estimation Equations
          By Robert J. Simeone
          My "6.5" = 24" AA Overwatch upper 1/9 twist, NC based US Tactical lower, standard A4 6 position stock, AR Gold Trigger, JPS SCS buffer, Vortex 6-24 x 50 FFP PST with EBR-2C MOA reticle

          Comment

          • Klem
            Chieftain
            • Aug 2013
            • 3509

            #6
            Originally posted by lrgrendel View Post
            Really good info.
            Anyone know the formula for "mils"?
            I take it you are working in all metric? Mils turrets, Mils reticle and measuring in metres on the ground?

            If so, it is the simplicity of the decimal system. 1Mil approximately subtends 1metre at 1,000metres.

            I say approximately because it depends on the convention you are using as to how many mils make up a full circle (NATO, Finland, USSR or Scope manufacturers' convention).

            The real trigonometric-derived number is 6,283 mils make a full circle. NATO has gone to 6,400 to make it easy to calculate. My Silva compass displays 6,400Mils in the full circle. I understand scope manufacturers use the real number 6,283.

            At 100M, dial up 10Mils and your reticle should be pointing 1 metre higher on the target. You don't have to fire any rounds if you have enough marks on the target to be able to identify where the reticle is pointing. 1 metre is about the height of Brian's board in the video.

            One qualification to the video. Brian talks about loosening the scope ring and rotating the scope if your rounds fall left or right of the dialled-up group. This assumes the gun is level...or in other words, the barrel and scope mount are absolutely vertical. Your vertical tracking might be perfectly vertical to start with but on the occasion you shoot these groups the gun itself is canted...Just saying.

            I remember printing out a similar tracking check as a utility of a ballistics program. Four or five A4 sheets that you print and tape together. They had increments large enough to see at 100yds through a scope. You dialled up and down your scope keeping your gun rested and still. Same check as Brian but just no shots are fired.

            That said, I am going to try this out tomorrow at the range.

            Good spot Nuggin, it's a helpful video and always good to check these things from time to time.
            Last edited by Klem; 06-19-2015, 09:26 AM.

            Comment

            • terrywick4
              Warrior
              • Sep 2014
              • 181

              #7
              Originally posted by Klem View Post
              One qualification to the video. Brian talks about loosening the scope ring and rotating the scope if your rounds fall left or right of the dialled-up group. This assumes the gun is level...or in other words, the barrel and scope mount are absolutely vertical. Your vertical tracking might be perfectly vertical to start with but on the occasion you shoot these groups the gun itself is canted...Just saying.

              .
              I think he said to adjust the level on the scope

              Comment

              • Klem
                Chieftain
                • Aug 2013
                • 3509

                #8
                Originally posted by terrywick4 View Post
                I think he said to adjust the level on the scope
                I am thinking adjusting the level on the scope means rotating the scope until it's level. Apart from pushing it forward backwards the only thing you can do is rotate it in the rings.

                To avoid second guessing what Brian means I put it to you there are three things that need to be level for us to believe any variation from the expected is down to a lack of calibration:

                1. The scope axis must be absolutely vertical to the bore axis when shooting (i.e. no canting the gun).
                2. The erector mechanism connected to the windage/elevation knobs needs to be
                absolutely vertical/horizontal to 1.
                3. The reticle needs to be absolutely vertical/horizontal to 2 and 1.

                I have separated 2 and 3 because it is unwise to assume the reticle is perfectly aligned with the windage/elevation turrets. I have seen this twice with Leupold MRT scopes (replaced under warranty without fuss).

                Comment

                • wraith1516
                  Warrior
                  • Dec 2014
                  • 316

                  #9
                  Great info was worth watching

                  Comment

                  • Kleinerk
                    Unwashed
                    • Aug 2015
                    • 6

                    #10
                    Tall Target Test

                    This was a neat test.

                    I scored an 8.

                    Not too shabby.

                    Thanks for sharing,

                    --Shawn

                    Comment

                    • IceAxe
                      Warrior
                      • Jan 2014
                      • 168

                      #11
                      Just thought I would add for clarification that milliradians are not really metric. A radian is the the length of the radius of a circle applied to the circumference. Milli refers to one thousandth. So a milliradian is a one thousandth of a radian. Though not exact, it turns out that one mill at a thousand meters is close to one meter in width.

                      Comment

                      • motoxxx_ryder
                        Warrior
                        • Mar 2015
                        • 180

                        #12
                        for anyone who wants to use this on a MIL reticle. the constant is 1/100th of the measuring metric. So hence the .01047 for MOA.

                        Mil constant is .036 for a measurement in yards.

                        Comment

                        • LRRPF52
                          Super Moderator
                          • Sep 2014
                          • 8569

                          #13
                          I had some very interesting conversations at SHOT with some of the industry's most prominent people who have been watching this closely.

                          Big takeaway is that cheap scopes are made with an interference fit in the gears so they track consistently when you first start dialing on them, but then they work-polish in and become loose.

                          Also, the manner in which optical lenses are secured in the tube is a huge deal, and very few companies epoxy their lenses in place.

                          Get a copy of Sniper Magazine for probably the best article on scopes I've seen ever, including exploded views, mechanical and optical engineering discussions for the layman, how the erector works, backlash effect, and much more.

                          You can run target tests like this, and if .1 Mil really matters to you, run the test every 6 months to verify you are still tracking.
                          NRA Basic, Pistol, Rifle, Shotgun, RSO

                          CCW, CQM, DM, Long Range Rifle Instructor

                          6.5 Grendel Reloading Handbooks & chamber brushes can be found here:

                          www.AR15buildbox.com

                          Comment

                          • dfp23
                            Bloodstained
                            • Nov 2015
                            • 39

                            #14
                            I do the tall target test frequently with my scopes. It eliminates the "scope variable" if you are encountering problems with your accuracy at longer ranges. And best of all it only takes 15 minutes for peace of mind. In addition to regular intervals, I do this test if i bang up my gun, new scope or diagnosing long range accuracy problems.

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