Diagonal movement of the crosshair while adjusting the elevation turret.

Jump to latest Follow Reply
JAMz

JAMz

Member
May 11, 2020
123
7
PR, United States
I have very limited experience with optics. So here it is,

The gun in question is an HW35e which has a very noticeable barrel droop. With the optically centered scope I'm getting about 5 inches low and 1.5 inches to the left. So as I adjust the elevation turret up, the poi simultaneously moves to the right, getting the poi closer to the point of aim with each shot. Therefore instead of moving straight up, the poi moves diagonally, if this makes sense.

This has happen to me twice with two different budget scopes ($150-$190) from different manufacturers but the same gun. Someone here suggested that this might be due to a tilted scope. Understandable, but the gun and scopes have been bubble leveled during the setup. I talked to one of the scope's manufacturers just to learn more about this and he told me that if there is too much vertical adjustment going on I could see this behavior. I think he said that this is due to the erector tube not having enough pressure form the internal springs. Whats your take?

Anyhow, I'm using an adjustable mount for this gun which serves me well but brings me another issue, eye alignment. With the adjustable mount sitting too high and the low vintage cheek piece of the gun the eye alignment is off. I'm thinking maybe a cheek riser could be a solution.
 
Your scope is most likely not mounted correctly. A tracking test is where you shoot at a large piece of paper that has a straight up/down line drawn on it. then the target is hung with a level to insure it's straight.

You make a small 1/4 dot (I use a sharpie) then you shoot at that dot. when you hit it, you start cranking the elevation knob (Keep aiming at the 1/4 dot) and watch you impact climb up the straight line... you keep doing this until you can get the impact to climb up that line in a straight manner.



If you see you impacts drift off diagonally, you scope is not mounted square..

Looks like this

https://i.imgur.com/iTD6UJH.jpg
 
Upvote 0
At what distance are you zeroing? Adjusting for 5” of vertical at 25 yards, for example, requires 20 MoA of compensation which for many inexpensive scopes will be most of their adjustment range. More opportunity for the tracking to depart from orthogonal as a result.

If you are zeroing at an even closer distance like 15 yards, the situation is even worse. Might need what is referred to as a “drooper mount” that has some amount of compensation built in, angling the scope downward. That way the erector tube stays nearer to its mechanical center where the tracking behaves closer to the ideal.

And as bandg pointed out, installing a scope with the aid of bubble levels can produce an errant result. See the following thread for a way to do it that will give a more confident alignment.

https://www.airgunnation.com/topic/best-way-to-level-a-scope-2/#post-1003404
 
Upvote 0
It could be either a scope tracking issue or a mounting issue. Best way to check tracking is with a laser bore sighter.

if it’s a mounting issue (more common), loosen the scope in the rings and rotate the scope 5 or 10 degrees clockwise. Retighten and repeat the exact same test. Do you see any improvement?

Note: the bubble levels are to aid in holding the gun while shooting, not necessarily for scope mounting.
 
Upvote 0
Harv24: That's a great tip. Thanks for sharing.

Nervoustrig: I'm sighting at about 11 yards. Thanks for the link. It seems like you learn something new every day.

On previous occasions I used a combination of a bubble level on the gun to keep it level on the gun vise and then looking at a plumb line thru the scope. Now that I think about it I think it gave me better results. Any how, I'm using sportsmatch adjustable mounts now.




 
Upvote 0
"Best way to check tracking is with a laser bore sighter."

It certainly is a great way to check if you have one. If not, the tall target method works for a lot of things. Shooting at a target with verified level vertical lines allows one to keep the reticle on the relevant line while cranking elevation up and down. If the scope is "level" and if the scope tracks along the reticle accurately, such shooting will show the POI moving only along the vertical line as elevation is dialed up and down.


 
Upvote 0
What type of bubble level are you using? (I've seen many that were in mounts that weren't square and level. Also worth noting - the bubbles flat cylinders sometimes won't move without 3-5 degrees of canting (never realized that until I got the Accuracy 1st levels).

If there's any doubt, I would use a plum bob and mount the scope in perfect overlap with the line and re-test the actual turret elevation tracking.
 
Upvote 0
That’s possible, yes. I took from his original post that the 1.5in lateral error had substantially closed in by the time he had dialed in the full 5in of vertical adjustment. At just 11 yards, there is so little projectile drop that the gun would have to be canted to such an absurd degree that it would be obvious. However after re-reading, I’m not so sure my interpretation was correct so you make a fair point.

On a general note, I like to take a divide and conquer approach to problems like this where there are several possible causes. So for example:

1. Is the reticle tracking true? Take the gun out of the equation. Clamp the scope in a vise and view a plumb line. Run the turret up and down to confirm it tracks along the plumb line.

2. Is the reticle properly aligned to the bore? Use the mirror approach or a laser boresighter to confirm.

3. What is left now? That the shooter must hold the gun level.
 
Upvote 0
I do a tracking test on all new scopes I use... tells you a couple of things.

- Do I have the scope level, and will all my elevation inputs move the strike of my rd straight and with out any left or right shift. That's what the tall target does.

- A box test. This tells me my scope is tracking correctly. 



A trick I learned to level scopes.. make a plumb bob using string and hang it from the ceiling. Place White chipboard behind it as a background. Then I secure my rifle in a sturdy vise/cradle. I made one out of wood many years ago. Make sure it will sit flat on a bench. Then I use a small level on the pic rail to insure its level.

Line up your scope and get it close to level, than align it so its pointing at the string. Take a bright flashlight and shine it thru the ocular lens and you should see the crosshairs as a shadow superimposed over the plumb bob. us that to align the vertical crosshairs to be in line with the Plumb bob.

The tall target is just to confirm that everything is level and square.
 
Upvote 0
"2. Is the reticle properly aligned to the bore? Use the mirror approach or a laser boresighter to confirm."

You can certainly do it that way. The tall target method will do the same thing objectively-i.e. seeing where your shots hit thus knowing when they are aligned. At the same time, you can be certain you have the reticle level while you mount your external level. One less thing, as Forrest would say.

"The tall target is just to confirm that everything is level and square."

The tall target can be used just to confirm, but it can also be used to do all the steps noted in setting up a scope. I've found it about as easy to do it all in one shooting session as it is to just use it to confirm.
 
Upvote 0
I do a tracking test on all new scopes I use... tells you a couple of things.

- Do I have the scope level, and will all my elevation inputs move the strike of my rd straight and with out any left or right shift. That's what the tall target does.

- A box test. This tells me my scope is tracking correctly. 



A trick I learned to level scopes.. make a plumb bob using string and hang it from the ceiling. Place White chipboard behind it as a background. Then I secure my rifle in a sturdy vise/cradle. I made one out of wood many years ago. Make sure it will sit flat on a bench. Then I use a small level on the pic rail to insure its level.

Line up your scope and get it close to level, than align it so its pointing at the string. Take a bright flashlight and shine it thru the ocular lens and you should see the crosshairs as a shadow superimposed over the plumb bob. us that to align the vertical crosshairs to be in line with the Plumb bob.

The tall target is just to confirm that everything is level and square.
Click to expand...

Shining a light through the scope is an interesting idea but the described method still has a flaw. "Then I use a small level on the pic rail" is relying on something that may or very well may not be "level".
 
Upvote 0
"2. Is the reticle properly aligned to the bore? Use the mirror approach or a laser boresighter to confirm."

You can certainly do it that way. The tall target method will do the same thing objectively-i.e. seeing where your shots hit thus knowing when they are aligned. At the same time, you can be certain you have the reticle level while you mount your external level. One less thing, as Forrest would say.
Click to expand...

FWIW I agree the tall target test is a good thing for final verification. I just don't find it to be particularly useful as part of a cookbook recipe for rifle & scope setup, or for troubleshooting and pinpointing a specific source of error. Let's say I do the test and it's off a little. What's wrong? Is my scope canted? Was I canting the rifle a little? Was there a bit of wind? Is my reticle not tracking properly? A combination of two of them? All four?

Yikes! Good luck sorting it out by trial and error. That's why I recommend individual steps for checking that the reticle tracks properly and the reticle is aligned properly to the bore and the rifle is held level. That way the user has a pretty good chance of success. And if it doesn't go quite right, he will most likely be able to say which setup step he has the least confidence in..and therefore which one to revisit to correct it. 
 
Upvote 0
Shining a light through the scope is an interesting idea but the described method still has a flaw. "Then I use a small level on the pic rail" is relying on something that may or very well may not be "level".
Click to expand...

Agreed. Referencing against some external feature of the rifle / receiver does not necessarily align the things that matter, which are the reticle and the bore. Probably better 99% of the time than just eyeballing it but still subject to subtle errors.
 
Upvote 0
"2. Is the reticle properly aligned to the bore? Use the mirror approach or a laser boresighter to confirm."

You can certainly do it that way. The tall target method will do the same thing objectively-i.e. seeing where your shots hit thus knowing when they are aligned. At the same time, you can be certain you have the reticle level while you mount your external level. One less thing, as Forrest would say.
Click to expand...

FWIW I agree the tall target test is a good thing for final verification. I just don't find it to be particularly useful as part of a cookbook recipe for rifle & scope setup, or for troubleshooting and pinpointing a specific source of error. Let's say I do the test and it's off a little. What's wrong? Is my scope canted? Was I canting the rifle a little? Was there a bit of wind? Is my reticle not tracking properly? A combination of two of them? All four?

Yikes! Good luck sorting it out by trial and error. That's why I recommend individual steps for checking that the reticle tracks properly and the reticle is aligned properly to the bore and the rifle is held level. That way the user has a pretty good chance of success. And if it doesn't go quite right, he will most likely be able to say which setup step he has the least confidence in..and therefore which one to revisit to correct it.
Click to expand...

We certainly view it differently, other than the wind bit. Yes, one needs calm conditions to do this. And there is certainly nothing wrong with doing things one step at a time, as you suggest. To me, shooting for a few minutes using that method can accomplish several things. The lines assure that one is always "holding level" with the scope for all shots. A couple of revolutions of the elevation turret up/down will quickly produce 2 POI's that provide feedback on whether the reticle is aligned with the bore. Rotation of the scope in the rings can then be done (if necessary) to align that correctly. Once that is done and the shooter knows that the bore is aligned with the reticle, he can then track elevation up and down and that will show whether tracking aligns with reticle. Assuming that tracking does match reticle (which it should in most scopes), this process does not take all that long at all. Finally, the shooter has a level reference (the lines) knowing that tracking follows reticle and bore is aligned with reticle and then the external level can be easily set. I've done it many times and do not find it difficult at all. Certainly might not be something that is good for everyone.
 
Upvote 0
While I agree his scope is probably not mounted properly, I also believe part of his problem is a "cheap scope". Most all scope mfgrs recomend not going more than one full turn of adjustment when setting up your scope. If you go to far the erector tube mechanics can be damaged and warranty voided! The poster should recenter his scope and use his adjustable mount to keep adjusters within one full turn. Use the examples given on here to mount his scope properly. Once properly mounted and the adjusters not strained he should be able to do a proper tracking test to see if his scope works properly. If an aftermarket cheek riser is needed, so be it, at least he knows his scope is good!!
 
Upvote 0
Thanks to all.



It is good to get several points of view on this subject. When I initially tried to scope the gun I had no idea that I was going to be dealing with a bad barrel droop. My other break barrel was a UK Tomahawk that had practically no barrel droop issue. After trying with medium mounts without good results, I used an adjustable mount and had it solved. Recently saw a gentlemen using a similar Hawke scope with fixed mounts on my same gun and decided to try it on my gun in order to improve eye alignment. But after the test I've gone back to the adjustable mounts.



I will definitively try the different methods for scope mounting to make sure I'm getting the best setup I can do. 
 
Upvote 0
You must log in or register to reply here.
Top Bottom
Back
Home
Forums
Resources
Menu