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

8K views 66 replies 8 participants last post by  bttbbob 
#1 · (Edited)
See comment below for full post... to avoid the photo compression that happens in the first post of every new thread.
 
#2 · (Edited)
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."
 
#5 ·
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!
 
#6 ·
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.
 
#7 ·
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.
 
#8 ·
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.
 
#14 ·
Ha! I think the reverse is true... the gun is better than me. So, when I do happen to get a fantastic group, it shows me how much I "suck" the rest of the time. Those sub-1/2-MOA groups are humbling. Because it shows me what the rifle can do... but, I can't with consistency. Any group I shoot bigger than, say... 1/3-MOA... is all MY fault, not the gun. :grin

It gets even harder at longer distances, where the wind comes into play. Then it can get very tricky. I really haven't delved into that side of the discipline much. A class with Bob would be good. Just time and money... time and money. ;)
 
#15 ·
Brownie, that's great that you found the time for all that training, my hats off to you sir.

Im just a country hunter in Oregon, although I have 27 deer, over 60 coyotes, and hundreds of sage rats with a 22-250 as memory's.

Now days, I like to shoot at steel plates and train my grandsons to shoot safely & have a good time.
Their mother wont spring for them going hunting yet (to young) but the day is coming.

Old Farmer..
 
#17 ·
Just curious racer88, did you measure the actual distance of the "100 yd" firing line? Is it exactly 100 yards? Not that it really matters much except for when documenting all of measurements used to determine the real precision of the scope's turret.
 
#18 ·
It's a good question, because from what I've read, it DOES matter. But, the short answer is: No.

I didn't measure it (trusted PBSO). :) But, yeah... ideally, we'd measure it. I don't have a tape measure that long and don't own a good rangefinder, yet. Do you have either of those? :)
 
#19 · (Edited)
Updating this thread. Today BeerHunter brought a tape measure to the range, since he planned run the Tall Target Test.

When I did it, I assumed the range distance was as marked... 100 yards. I didn't have a tape measure that long, nor did I have a rangefinder.

Well... today, we discovered it wasn't exactly 100 yards. Rather, it was 96.28 yards. Almost 4 yards short.

It makes a difference in the calculations. A pretty big difference! So, I re-ran my numbers, using the corrected distance.

The good news is that my scope is tracking even better than I previously thought / calculated. Instead of being 6% off, it is only 2.35% off. So, instead of the corrected click-value being 0.235-MOA, it's actually 0.244-MOA. In other words... neglible.
 
#25 ·
Center of bore to center of scope tube.
 
#27 ·
Hi guys! In the latest version of Strelok Pro, they've added a Click Value Validation calculator! Pretty nifty for when you do a Tall Target Test. You won't have to do the math manually! :grin

I made a video demonstration. See what you think!

 
#28 ·
Great tutorial Mike! StrelokPro is amazing and they seem to update/upgrade regularly to have the most accurate and user friendly ballistic app. This is awesome.


Sent from my iPhone using Tapatalk
 
#37 ·
You have to be carful when validating turrets and tracking.
Some reticle sand turrents are not true MOA or true milk. You have to read your owners manual. Some MOA turrents and scopes are IPY vs true MOA at 1.047. Some mislead/Mil-Dot are not true mil 3.66 but instead are 3.6.
 
#41 · (Edited)
OK... I have three different ballistic apps on my phone. All three allow different angular unit choices. But, only Strelok makes it easy to select the units for each scope / rifle profile.

The other two (Ballistics ARC and Hornady's new 4DOF) allow a general setting for angular units for the program. You might be able to set it individually for rifles / scopes. But, it's not obvious (to me) how to do that.

Many shooters may own rigs with MOA and MIL. With Strelok, it's super-easy to set up each rifle / scope profile accordingly. You can choose the angular units for each rifle / scope profile. The other programs... not so much, from what I can tell. With the other programs, it appears you can choose just one angular unit for the whole program. I may be wrong, but I didn't see it.

Strelok Pro - It appears that only Strelok offers ALL FOUR angular measurements that Bob referenced.



Ballistics ARC:



Hornady 4DOF:



I admit that I've only dabbled with the Ballistics ARC and Hornady 4DOF apps. The main reason that I've only dabbled is that NEITHER are intuitive to use. Strelok really shines in that respect. It seems (to me) that Strelok is pretty comprehensive (and offers the same features as the others). But, man, it's WAY easier to use.

Another big thing in the "plus column" for Strelok Pro is the responsiveness of the developer, Igor Borisov. Super-duper responsive! He's constantly improving and adding stuff to it. For example, when someone asks him to add a cartridge or reticle to the library, he just does it. Almost immediately.
 
#47 ·
I am a wealth of worthless info
 
#48 ·
Ha! I can quote countless lines from "Blazing Saddles" and virtually every episode of "Seinfeld." I can also recite one-hit-wonder bands from the 80s.
 
#51 ·
Looking deeper in the manual for my Nikon M-223 scope...

The windage and elevation scales of the M-223 Riflescope are calibrated in divisions of 1/4 minute of angle, with a click at intervals of 1/4 minute of angle
But, on the turret, it says, "1 click = 1/4 inch!"

Whiskey Tango Foxtrot!?! Which is it???
 
#52 ·
Looking deeper in the manual for my Nikon M-223 scope...



But, on the turret, it says, "1 click = 1/4 inch!"

Whiskey Tango Foxtrot!?! Which is it???
I read that as.... if 1” (rounded off) at 100yds is 1 moa then, 1 click is 0.25” at 100yds.


Sent from my iPhone using Tapatalk
 
#54 ·
OK... I just sent a message to Nikon, asking them if the turrets are calibrated in MOA or IPHY (since the owner's manual is self-contradictory). It will be interesting to see their response. :)

Anyone wanna bet Bob is right? ;)

That being the case, they did a really crappy job of writing the manual!
 
#55 ·
Bob is 100% right. It's either MOA or IPHY! :rofl

Seriously though, based on the ambiguity of the manual vs. turret markings, my money is on Bob's conclusion that it's IPHY. :popcorn
 
#56 · (Edited)
Bob is 100% right. It's either MOA or IPHY! :rofl

Seriously though, based on the ambiguity of the manual vs. turret markings, my money is on Bob's conclusion that it's IPHY. :popcorn
Exactly. :grin

I just want to make Nikon admit it! :smack
 
#59 ·
And they are going to tell you that it’s the standard in the industry and show you 5 other manufacturers that do the same thing.
 
#60 · (Edited)
I got a reply!

Thank you for contacting Nikon. The M-223 adjusts in shooters MOA, so the turret adjustments are 1/4inch at 100yards. Any other questions or concerns you may need, please don't hesitate to contact us back via your account or at our toll free number at 1-800-NIKON-US (1-800-645-6687).
Ah... so they call it, "Shooter's MOA!" LOL! Tricky, tricky! So, they should write it as "SMOA" or "IPHY" in their manual, not "MOA." :banghead

That said... by my calculations... at 600 yards (the longest practical range for my AR-15), by using the wrong angular unit (MOA instead of SMOA) in my Strelok Pro app, I would be 1/2-inch off. Doesn't sound like much, and it isn't if you're shooting steel. But, for an NRA-type bullseye target, it could be the difference between an X-ring and a 10-ring... or a 10-ring and a 9-ring. Of course, that's assuming I'm doing my part.

:dogtail

But, I'm glad Bob brought it up. Even though my turret was marked '1/4" per 100 yards', I wrongly assumed that it was a general "hint" as a way to estimate the change in POI.... rather than being literal. It's literal. I have since adjusted the scope profile in Strelok Pro accordingly.

PS... I've been jonesing for a better scope for my precision AR-15.
 
#62 ·
What they actually mean is it’s a IPHY. But whatever makes them sleep at night. As I said.
 
#64 ·
That’s enough to miss low at range! I asked that question because it made sense in my head but, could not figure it out (not mathematically inclined). Thanks for clearing it up.


Sent from my iPhone using Tapatalk
 
#65 ·
Yep. The difference between a hit and a miss! A 2.4% (.25 to .244 MOA / click) discrepancy adds up over a longer distance.
 
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