Calculators (Velocity, Energy, BC, Angle, Trajectory, Fill, etc)

Forums Knowledge Center Calculators (Velocity, Energy, BC, Angle, Trajectory, Fill, etc)

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    Michael
    Keymaster
    Keymaster

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    Credit – Steve in NC

     Download 1568652543_8993802765d7fbcff587cb7.55803177_Rifle_Trajectory.xls

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    sendler2112
    Participant
    Member

    Chairgun and Strelok setup:

    Copying this post here from a reply I made in another thread so it is easier to find again next time I want it.

    There are some tricks to making Chairgun work better than just using a measured scope height and the listed BC. Start with the listed BC and weight for your projectile either in Chairgun or from the web and the muzzle velocity and enter a good estimate of your scope height.

    Zero the scope at the first zero of 20 yards which is a range where minimal drop will have occurred.

    Zero the scope at 20 yards and enter that as the input to chairgun

    Take note of the elevation setting on the turret.

    Enter 10 yards as the zero in Chairgun. Read the chart as to what it says the clicks will be.

    Zero at 10 yards (hopefully your scope can come up to this) and compare on the chart the number of clicks that it told you to use, and the number of clicks that you actually used. 15 yards could work but wouldn't have as much resolution as at 10 yards. 12 1/4 moa clicks for 15 yards versus 45 clicks for example.

    Adjust the value of scope height in Chairgun until the chart matches the actual value of clicks that you found. This is what Chairgun thinks your scope height is. I have found that this might be quite a bit different than what you can measure for some reason.

    Now to get the BC set as best: Stretch out the range as far as you might want to shoot/ have room for/ can still get a reasonable group, in 5 yard increments. 50-60 yards at least. Compare the actual clicks to what Chairgun predicted as the difference from 20 yards and adjust the BC entry until they match. This is essentially the same as using the POI drop calculator for BC from the toolbox.

    When you are done with these calibration steps you can then calculate the zero that you may want according to Chairgun and the fly through of the point of impact and your desired kill zone tolerance using the "optimum zero range" button under the toolbox tab.

    I usually set a .5" kill zone and then remember I am 1/4" low at 13 yards, 1/4" high at 35, and 1/4" low at 40 for example with my Mrod .177 with it's low scope height so that I don't have to click within those ranges. If you use a zero stop and never want to hold or click "under", set the kill zone to 0.01" and the near and far zero will be the same with no point of impact above..

     

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