What is the turret click value on your scope... REALLY?
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Thread: What is the turret click value on your scope... REALLY?

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    Distinguished Member racer88's Avatar
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    What is the turret click value on your scope... REALLY?

    See comment below for full post... to avoid the photo compression that happens in the first post of every new thread.
    Last edited by racer88; 11-03-2018 at 04:52 PM.
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    Distinguished Member racer88's Avatar
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    I thought I'd start a separate thread on this topic.

    As I continue to evolve as a precision shooter, I am always learning new things. Man, you can really get deep into this discipline! But, that's what I like about it. It's very technical. It's scientific. It's applied Physics. And, of course... the human element. So, as much as I can apply the science, there's always going to be the "art" of it, too. Fun!

    So... our scopes come from the manufacturer with a number of different "specs." One of those specs is the turret click value. Most scopes designed for precision shooting have turret clicks that are 1/4-MOA or 1/10-MIL. I'm an "MOA guy," for now. So, according to the manufacturer of my scope, each click of the turret is 1/4 or 0.25-MOA.

    BUT IS IT REALLY???

    According to what I've read, many scopes are not EXACTLY calibrated to the value in the specs. They can be off a bit. At close distances, it may not matter. For hunting at normal distances, it is probably "close enough" to get in the "vital zone." But, for precision target shooting, it can matter. At longer distances, it can matter even more.

    There are various tests you can run to see if your scope is "tracking" well. One of them is the "Tall Target Test." The purpose of this test is to determine the ACTUAL turret click value of your scope. Then, when you are using a ballistic calculator to spit out a "firing solution" at a distance beyond your zero, you will get a more precise result. Make sense?

    Here's a link that explains the Tall Target Test process.

    So, I went out to the 100 yard range today with the mission of determining my scopes true click value.

    Basically, you just need a vertical line down the middle of a tall piece of paper. It needs to be perfectly vertical when it's stapled to the target backer. I used a plumb line to verify. Naturally, your scope needs to be level with your rifle. And, when you're shooting this test, you need to be sure that your rifle / scope is vertical.

    After you've confirmed your zero.... Pick a spot near the bottom of the vertical line as your "bullseye." Shoot a group there. Then dial 20 or 30 MOA (or MIL equivalent) UP in elevation. How much... depends on how much room you have to dial up. But, the more the better. In my case, 20 MOA worked well. The first time I did it, I dialed up 16 MOA.



    The "Tall Target Test" yielded some very interesting results. I ran the test twice. Both times, the result was EXACTLY the same... to three decimal places! Here are my calculations.



    As you can see, my Expected Point of Impact Shift (EPOIS) with 20-MOA (80 clicks) dialed would be 20.94 inches (20 MOA x 100 yards x 0.01047). But, the ACTUAL Point of Impact Shift was 19.688 inches. It was short.

    The Correction Factor is what I would use if I didn't have a ballistics app that allowed me to input the actual click value. So, if a ballistics chart (that assumes true 1/4-MOA click value) told me I need to dial UP by 16 clicks (or 4-MOA) for a particular distance, I would multiply that by 1.0636 (about 6%), which would be 17 clicks of actual dialing. If the chart told me I need to dial 40 clicks (10-MOA), that would be 43 clicks of actual dialing.

    But, since Strelok Pro allows me to enter in a corrected click value, and my scope's actual click value is short by 6% (6.36%, to be precise), I can just do the reciprocal of 1.0636, which is 0.235. My scope's actual elevation click value is 0.235-MOA. Done another way... 94% of 0.25 is 0.235. I hope that made sense. <img src="https://www.floridaconcealedcarry.com/Forum/images/smilies/smile.png" border="0" alt="" title="Smile" class="inlineimg" />



    Consider that at 600 yards, a 0.235-MOA discrepancy comes to 1-1/2 inches.... or half the diameter of the F-class target x-ring (3-inches). So, uncorrected, if I'm holding at the dead-center of the x-ring, the shot would be just off at the bottom... in the 10 ring.

    At 1,000 yards, it's a 2-1/2 inch discrepancy.

    So, not a HUGE difference, if I'm hunting or ringing steel. But, in a match... could make a difference, eh?

    So, the cool thing about Strelok Pro (ballistic app) is that I can enter that 0.235-MOA click value into my scope's data. Now, the app will give me more precise "firing solutions."
    Last edited by racer88; 11-04-2018 at 02:48 PM.
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    Distinguished Member brownie's Avatar
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    The mind is the limiting factor

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    Distinguished Member DGOrlando's Avatar
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    Excellent stuff!

    Thank you.


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    Really great thread, racer! Among other things, I need to go through that drill, too to really learn the behavior of my scope. My challenge is getting enough time on a suitable range. Hope to be at PBSO both days in a couple of weeks, this time with my rifle on a sled to minimize one of the biggest variables. . .me!
    -BH

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  7. #6
    Distinguished Member racer88's Avatar
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    Quote Originally Posted by BeerHunter View Post
    Really great thread, racer! Among other things, I need to go through that drill, too to really learn the behavior of my scope. My challenge is getting enough time on a suitable range. Hope to be at PBSO both days in a couple of weeks, this time with my rifle on a sled to minimize one of the biggest variables. . .me!
    Yeah... that variable is the one that challenges me and the reliability of the data being gathered.

    So.... does a lead sled make a difference, though? Is it better? Logically, it would be. But, if you search on Google, you'll find a TON of links to discussions and articles about the Lead Sled adversely affecting accuracy vs sand bags.

    I'd be interested to hear what Bob has to say about using a sled.
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    Member Old Farmer's Avatar
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    Racer, good post!

    I have done this with a L R bud I have at the range. The trijicon scope and the shepherd scope tracked great, the bushnell scope was given away shortly there after.
    It makes sense to buy a quality scope, unless you are shooting under 100 yds.
    Im an avid deer hunter and rely on long shots many times.

    again GOOD POST.

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    Distinguished Member brownie's Avatar
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    Quote Originally Posted by Old Farmer View Post
    Racer, good post!

    I have done this with a L R bud I have at the range. The trijicon scope and the shepherd scope tracked great, the bushnell scope was given away shortly there after.
    It makes sense to buy a quality scope, unless you are shooting under 100 yds.
    Im an avid deer hunter and rely on long shots many times.

    again GOOD POST.
    You have an 8" target on a deer. If your scope is off 1" on the turrets at 200 yrds, it's not going to matter whatsoever. The ONLY time you need as much precision as Racer is getting to with his set up is if you're going to try to shoot the eye out of some perp or for score on paper in matches.
    The mind is the limiting factor

    https://www.youtube.com/user/azqkr

    The lion does not even bother to turn his head when he hears the small dog barking..

    Stay Sharp

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  10. #9
    Member Old Farmer's Avatar
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    Quote Originally Posted by brownie View Post
    You have an 8" target on a deer. If your scope is off 1" on the turrets at 200 yrds, it's not going to matter whatsoever. The ONLY time you need as much precision as Racer is getting to with his set up is if you're going to try to shoot the eye out of some perp or for score on paper in matches.
    Brownie,

    You're absolutely right. However when I hunt coyotes, the target is much smaller.

    Although: I dream about shooting at large animals instead of people, they taste better !

  11. #10
    Distinguished Member racer88's Avatar
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    Quote Originally Posted by Old Farmer View Post

    Although: I dream about shooting at large animals instead of people, they taste better !
    Ummm.... dare I ask how you know?
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