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Long range, tall target test, scope adjustment for not tracking

EricE555

When I do the tall target test I find that my scope doesn't track perfectly. at 30 clicks up it is off to the side by 1 inch or so.
The instructions for offsetting this have you calculate an adjustment factor and then use that for every different shooting situation.

My question:
Does it make sense to just tilt your scope such that you have no offset 30 clicks up and then you wouldn't need an adjustment factor...or is this somehow different than having a scope that tracks perfectly?
 
The tiny levels used to set your scope can lie. You need to verify reticle level with a plumb line.

What distance are you seeing this ? What scope do you have ? What click adjustments? Have you confirmed at distance ?


Assuming 1/4 moa clicks and 100 yards - your 30 clicks (7.5moa) isn’t really a tall target test. Those are usually run at 15-30 moa or 60-120 clicks up for 600-1000 yards Dope settings.

But again assuming your range is limited to 500 yards so that number is appropriate, the 1 inch ( assuming 100 yards , 1 MOA) offset can be factored in if it is repeatable. When I shot iron sight service rifle all my zeros had both windage and elevation settings as the front sight tower is damn near impossible to get plumb to the gnats wing. 600 dope was 52 clicks up 5 left.


If you have a cheaper scope and are at the end of the travel and bottoming out the reticle in the erector tube, that can deflect the reticle to the right or left as well. Always better to be near the middle of travel or the dope than extreme for windage or elevation.
 
+1 on Jeff's advice.
Before you spend rounds doing your dope, I would run the tall target tests (on both axes).

Sometimes there is just reticle rotation error, sometimes there is gimbal orthogonality error.

Orthogonality error is where the azimuth and elevation tracking do not run 90 degrees to each other.
Reticle rotation is where the cross tracks correctly, but the reticle is tilted.

You can always decide how to handle errors once you have them understood, but you will want to know the difference between reticle rotation versus gimbal orthogonality error before you make your decision.
 
I am using a Leupold Vari X III. I was very careful when I mounted it (and had the proper tools) but that still does not eliminate the possibility of error. I'll try a plumb bob to see if it reveals anything. Also, when I say 30 clicks up, I just cranked it up to near max range. My scope is a CDS and it has the compensator in it for my round. So I just cranked it up to 600 yards. I think 650 is max on the dial. But I just realized that I could pop out the compensator and put in the one that came with the scope which puts it back to a normal adjustment scope. That would allow me to say exactly how many clicks up. I would need to do that if I were going to use any sort of adjustment factor anyway.
So for testing for orthogonality in the horizontal, I imagine I need to crank it out to the right or left a bunch and see if the bullet moves ONLY horizontally. right?

Re Jeff Porter: 100 yards. No, I have not confirmed at distance. Ideally I would dial (account for) all error out before I go to distance.

Re Region Rat: Thank you. This gets at the heart of my question. And you answered with "it depends on what kind of error yours is." That makes perfect sense and I now understand better what kinds of errors there could be. This helps.

Great Forum guys. Thanks for all your replies. I'll post back with anything I discover.
 
I also have a barely used VX III in a 8.5x25 with the target turrets and the tracking was way off. Dialing for long range was a total disaster to say the least. I sent the scope in for repair at a Leupold warranty centre up here in Canada and it needed a new erector spring and erector system on a barely ever used scope. A bonus was there was no charge whatsoever for the repair which was awesome. Now the scope tracks perfect. You may want to look at sending your scope in for repair.
 
EricE555 said:
I am using a Leupold Vari X III. I was very careful when I mounted it (and had the proper tools) but that still does not eliminate the possibility of error. I'll try a plumb bob to see if it reveals anything. Also, when I say 30 clicks up, I just cranked it up to near max range. My scope is a CDS and it has the compensator in it for my round. So I just cranked it up to 600 yards. I think 650 is max on the dial. But I just realized that I could pop out the compensator and put in the one that came with the scope which puts it back to a normal adjustment scope. That would allow me to say exactly how many clicks up. I would need to do that if I were going to use any sort of adjustment factor anyway.
So for testing for orthogonality in the horizontal, I imagine I need to crank it out to the right or left a bunch and see if the bullet moves ONLY horizontally. right?

Re Jeff Porter: 100 yards. No, I have not confirmed at distance. Ideally I would dial (account for) all error out before I go to distance.

Re Region Rat: Thank you. This gets at the heart of my question. And you answered with "it depends on what kind of error yours is." That makes perfect sense and I now understand better what kinds of errors there could be. This helps.

Great Forum guys. Thanks for all your replies. I'll post back with anything I discover.
Click to expand...
I use a double yardstick free hanging from a nail on the top so it acts like a plum line. Then use the measurement markings to test tracking error rates.

Screenshot_20240205_173920_Chrome.jpg
 
Eric -What load is this calibrated for ?

Does your CDS only have one revolution for your range of distances ?

Did you zero the rifle elevation at the lowest number on the dial before mounting the knob?

Just want to be sure you didn’t pull the CDS out of the box and put it on the scope. The turrets usually come at the center of travel.
 
I setup a plubline/plub bob in the garage and found my mounting to be perfect...or as close as I can detect.
I ended up sending the scope in for warrantee. We'll see what happens.

Jeff P: calibrated...as in sighted in? I was zeroed for 100 yards. yes, 1 is the lowest on the dial and it was sighted in on that number. The dial only goes around once, which gets me to 650. I have never target shot beyond 200 and never consistently. This summer I'll be doing that to try out my new chassis, a MDT (ORYX CHASSIS).

Lead Slinger: that is brilliant
 
EricE555 said:
When I do the tall target test I find that my scope doesn't track perfectly. at 30 clicks up it is off to the side by 1 inch or so.
The instructions for offsetting this have you calculate an adjustment factor and then use that for every different shooting situation.

My question:
Does it make sense to just tilt your scope such that you have no offset 30 clicks up and then you wouldn't need an adjustment factor...or is this somehow different than having a scope that tracks perfectly?
Click to expand...
Sounds like your scope needs to be leveled.
 
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