Point of impact change while changing power on VXIII LRT?

[Hired Gun]

I just got a new laser bore-sighter and decided to see how close it was on my rifle that was just at the range yesterday. It was very close but I noticed something very disturbing when I played with the zoom on my scope. This is a brand new VXIII 8.5-25x50 LRT 30mm scope with the varmint reticle. At 200 yards the cross hairs move up from just under the 200 yard center bulls eye to centered between the 300 and 400 hairs or about 5" vertically in relation to the laser point when I zoom from 8.5 to 25. I haven't confirmed with actual shooting as I never zoom the scope lower than 25 power for shooting. I have a bunch variable scopes and they all live on their highest power.

If I ever had to turn the zoom that far down the trajectory is going to change a bunch as well and would need to be compensated for anyway. I will be range testing this later this next weekend.

I'm also wondering that since the change is purely vertical that there is some sort of other phenomena here that is explainable. With a variable range I expected the laser to appear higher and lower and it does, but on a fixed range just moving the power ring, I did not expect that much movement. The AO did have any affect on the elevation change as I was holding still and having my son run the zoom and AO so I could watch it move. It didn't matter exactly what we were aiming at as the relationship that was changing was the crosshair intersection to the where the bore was pointing.

I will be testing all my scope eventually especially my 8-32 BD and the scopes on my rim fire rifles as they are the only ones that ever get the power rings moved for shooting.

Has anyone ever noticed this before? Is it fixable or really not an issue?

 

[royinidaho]

I'll be interested in your test results.

Just for grins try your other eye and see if the condition changes.

Also do the the "cross hairs" straight or crooked.

This reponse may seem strange but it happened to me.

 

[Hired Gun]

It does the same thing for everyone that looks through it. The dot stays right on line throught the elevation changes from the elevation turret.

 

[CatShooter]

If you are using the laser at close range, don't worry.

Try the gun at the range at high and low powers with real bullets.

 

[Jerry Ricker]

Hired Gun, it's not a common problem but you see it once in a while with Leupolds. The reticle cell is not centered within the erector tube, seen it more than once. Send it back to Leupold, they have pretty good customer service, they'll know what the problem is.

 

[CatShooter]

[ QUOTE ]
Hired Gun, it's not a common problem but you see it once in a while with Leupolds. The reticle cell is not centered within the erector tube, seen it more than once. Send it back to Leupold, they have pretty good customer service, they'll know what the problem is.

[/ QUOTE ]

???

Hello... The reticle is NOT located in the "erector tube" - if it was, you could NOT adjust the elevation and windage. Also, the reticle MUST be located in one of the image planes, and there is NO image plane in the erector cell.

The reticle is located behind the "erector cell" (the proper term), and is in a fixed mount.

How did you see it more than once??? Curious minds want to know.

Read this and get some edjumacation:

http://www.snipercountry.com/Articles/Parallax.asp

-

Hired Gun...

DON'T waste your time sending it back to Leupold. If you send it back and tell them that it's broke cuz you used a bore sighter, they will laugh so loud that they will be heard in New York City.

Do the smart thing and take it to the range, adjust the eye piece properly, and focus the objective for the range you are using, and then shoot the **** thing.

.

 

[Brown Dog]

Catshooter,

Firstly, I know very little about scope internals /ubbthreads/images/graemlins/smile.gif.

Secondly, I think you may have misread the original problem posted.

The issue has nothing to do with the laser; that is incidental information.

The fellow is getting an apparent zero shift when viewing a 200yd target and changing power setting.

...unless of course I've misread it /ubbthreads/images/graemlins/smile.gif

As such, misalignment of the 'whatever' cell seems a reasonable cause...(to my optically unedjumacated brain).



(...and why you former colonials buy 2nd plane scopes is beyond me /ubbthreads/images/graemlins/confused.gif /ubbthreads/images/graemlins/smile.gif /ubbthreads/images/graemlins/smile.gif)

 

[Chrismadrid]

[ QUOTE ]
Hello... The reticle is NOT located in the "erector tube" - if it was, you could NOT adjust the elevation and windage. Also, the reticle MUST be located in one of the image planes, and there is NO image plane in the erector cell.

[/ QUOTE ]

It's perfectly feasible for an image plane to be in the erector tube as opposed to the erector cell - most modern FFP scopes are proof of that.

A SFP reticle COULD be also in the erector tube, but it's technically easier to mount rectilinearly with the outer tube.

POI shift with SFP zooms is pretty commonplace - though not normally in mid/high optics. It gets more visible the further you adjust off optical axis.

I'd send back as as unacceptable.

Oh - And I have to agree with Brown Dogs closing statement. /ubbthreads/images/graemlins/grin.gif

 

[CatShooter]

Sorry Chris... but what you said is not technically possible.

Read this to find out why...

http://www.snipercountry.com/Articles/Parallax.asp

 

[Chrismadrid]

Look at this - I have a better one somewhere (S&B) and a and a PHOTO of a cutaway - will keep looking. Also have some russian factory drawings.

This I think is how Hakko were doing things - came off HORUS site.

And I <ahem> take scopes apart REGULARLY. Not S&B's you understand.

 

[Chrismadrid]

Not sure if this helps but

This

looked like this

inside.

Nº3 most definitely was the reticle - mounted upside down of course and nº4 the erectors - it was the precursor of this

in whose development I was actively involved.

POI shift in SFP zooms is a known fact of life. An expensive scope should not exhibit much - maybe 1 click or two max. I've seen TASCOS shift 10MOA.

It is documented as more common on VXII than VXIII Leupolds.

As an aside sloppy sidewheel and AO mech's as well as sloppy ocular adjusters can cause POI shift too - not just poor zoom controls and erector cams.

 

[Hired Gun]

I thought you all forgot about me. I did call Leupold and they said try it first and if it shifts no problem to fix. I tried all my other 1" variable Leupold scopes and the lazer dot is constant no matter what power they were set on. I would have bet money the LRT was defective.

I finally got a break in the weather last week end and got to spend some time on the bench with it. 3 shots on 25 power. 1/2 group as usual shooting from the bipod over the folding table. I spun it down to 8.5 and ran 3 more right into the same group. No detectable group shift! I'm glad I didn't send it in or bet any one. There must be some simple explanation but why doesn't any of my other scopes do this?

My faith is totally restored in this and all Leupold scopes.

No who from Coos County wants to go beat up on my steel targets in less than perfect weather? It's no fun without witnesses.