How to Zero a scope?

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Mtl_Biker
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How to Zero a scope?

Post by Mtl_Biker » Wed Nov 01, 2017 1:55 pm

If you're zeroing a scope for field target use, how do you go about it? Do you (as I did) determine the optimal zero distance (with the help of a chrony and Chairgun) and then with the rifle supported (I used a solid table, my bipod in the front and bags under the stock) zero the gun?

Or do you assume your most usual field target position (sitting on the ground as we do) and try to zero the gun that way?

I'm asking this because I'm not doing well with my shooting. I zeroed my rifle with it well supported and it's really perfect. But when I take my sitting position (unfortunately I haven't yet done this at my optimum zero distance, but will, hopefully first thing in the morning) my shots seem to impact fairly consistently low. I've been thinking that this is MY problem... something wrong with my technique, perhaps trigger control, but gee, no matter how much I practice, my shots are still low. Oh, the occasional shot is on target, but that might be because of my movement but most shots are consistently low.

My practice shooting (at my office back warehouse) has always been at the longest distance from my target that I'm able to use... about 23 yards. And with my 1/8 MOA scope, that's 9 clicks down. (Supposedly.) I didn't see the use of practicing at closer distances. But now that I'm wondering strongly about whether it's my technique or something else, I'm going to try this at the optimum zero distance, supporting the gun as I would in a FT competition.

My question remains... Is it better to zero the scope with the gun well-supported as I did, or in your most usual shooting position?

Thanks for your comments.
AA S400 MPR FT - Sightron 10-50x60 SIII FTMIRMOA
CZ200S "Green" - Airmax 30SF 6-24x50
AA S510 Xtra FAC Ultimate Sporter Carbine (.22) - Airmax 30SF 4-16x50
Steyr EVO-10 (Pistol)
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pirellip
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Re: How to Zero a scope?

Post by pirellip » Wed Nov 01, 2017 2:20 pm

If you're using this rifle for FT, zero it from your FT position. Don't worry about where the pellet lands when you're shooting off a bench - it doesn't matter.
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Re: How to Zero a scope?

Post by Mac » Wed Nov 01, 2017 3:33 pm

After I set my zero from the FT sitting position, based on the chairgun suggested zero, I then do real world shooting to confirm the click settings at select distances. Especially at the Grenville club with the tiny hit zones, I confirm/set the click setting for every yard from 9 yards to my zero. After the zero section of the chart, I set up every couple of yards, up to about 40 yards and then set every five yards from 40 to 55 yards. The click values in between the five yard marks are easy enough to extrapolate as most progress by one or two clicks.

Sounds like a lot of shooting, but I like shooting. I never do this in one sitting, since fatigue will be a factor after sitting in the FT position for an extended period. I am setting up a gun at the moment and set my zero and confirmed settings from 10 to 16 yards yesterday afternoon. I will set from 17 to 21 and the spots beyond my zero on Friday. I will confirm them Sunday morning on the sight in range at the match and make any adjustments necessary based on how the gun shoots on Sunday. That last sentence is very important and should be done before every match. A PCP may only need about five shots to confirm the settings, but a springer needs that many shots just to warm it up and settle it down. If there is something a little off, adjust the scope to compensate and if all shots line up, you are good to go.

For me, all this shooting is done from a FT sitting position, just as I would in a match.
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Re: How to Zero a scope?

Post by ynoT » Wed Nov 01, 2017 4:05 pm

Great posts on zeroing one's scope. What I haven't seen mentioned is determining scope height. I believe it is an important aspect in the zeroing process. I personally am not sure how to determine an accurate scope height and would appreciate very much someone's input on this topic.

Tony

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Re: How to Zero a scope?

Post by Mac » Wed Nov 01, 2017 5:19 pm

I use a micrometer and measure the diameter of the scope tube divided by two, the space between the scope tube and the barrel and the diameter of the barrel divided by two and add the three together. This gives me the distance between the centre of the scope and the centre of the barrel.

Some use the instructions on Chairgun to figure the scope height, but my method has worked fine for me.
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pirellip
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Re: How to Zero a scope?

Post by pirellip » Wed Nov 01, 2017 5:52 pm

I agree with everything Tim has said about setting up your clicks. I *wish* I had the time and space to do this process, but I don't.

There are several ballistic programs out there, but PP Calc (only for Android) is the best one, in terms of ease-of-use and real world accuracy.

https://play.google.com/store/apps/deta ... slad.rwpoi

With regards to how to find your scope height, what I do is:

(A) Use calipers to measure the diameter of the front of the scope.

(B) Measure the distance from the bottom of the scope to the top of the barrel.

(C) Measure the diameter of the barrel.

Scope Height = 1/2(A) + (B) + 1/2(C)

Yes, this method assumes that your POA is at the mechanical centre of the scope (which it won't be), but it seems to always work pretty good.
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Re: How to Zero a scope?

Post by ynoT » Wed Nov 01, 2017 9:06 pm

Thanks Tom,
I do something like what you do but I do the measurement just behind the elevation turret. (Where is the reticle situated? I guessed that it is below the turret.
Using a similar procedure as you I measure the diameter of the scope-tube and the probe and do as you do. Doing that our end product should be pretty close. What do you think.

Tony

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Re: How to Zero a scope?

Post by pirellip » Wed Nov 01, 2017 9:42 pm

That should work fine too Tony.
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Re: How to Zero a scope?

Post by Mtl_Biker » Thu Nov 02, 2017 9:02 am

Thank you so much, guys!

I feel like an idiot! Since getting this Sightron scope I've been struggling to hit my targets (and coming in last at the competitions). I kept re-zeroing the scope (with the gun fully supported as I said) and then figuring it was my shooting technique that was keeping me from hitting where I was aiming. That, and I also kept cleaning the barrel, thinking that perhaps a dirty barrel was keeping the shots from hitting where I wanted.

Anyway, this morning for the first time, I sat down in the FT sitting position I use in competitions and at the optimum zero distance and found that again I was consistently hitting below my point of aim. I re-zeroed as best I could, and my accuracy improved drastically. Later (once staff go home) I'll try again at the max distance I can in my warehouse. But my initial results seem to indicate that I was wrong to zero the gun with it fully supported on a table. That I should have done it in the FT sitting position I mostly use. SIGH

Thanks guys!

(Oh, and yes, I use a caliper to carefully measure and calculate the scope height for Chairgun.)
AA S400 MPR FT - Sightron 10-50x60 SIII FTMIRMOA
CZ200S "Green" - Airmax 30SF 6-24x50
AA S510 Xtra FAC Ultimate Sporter Carbine (.22) - Airmax 30SF 4-16x50
Steyr EVO-10 (Pistol)
FWB 800 Evolution Top

ynoT
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Re: How to Zero a scope?

Post by ynoT » Thu Nov 02, 2017 3:06 pm

Did you level the scope when you installed it?

1. I use a level that can be attached to the the scope-rail.
2. Put rifle in a rest and center the bubble in the level.
3. Rest scope loosely in scope rings.
4. Place plum bob at a distance around 10 yds.
5. Make sure rifle is dead level and look through scope.
6. Make sure that the vertical cross-hair is aligned perfectly with the plumb bob's string.
7. Tighten scope. Should now be level with rifle.

Might not be the best method but that's how I do it.

I am still a Newbie to the airgun world.

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