Scope question

sounds like thing are not aliened right id leave it at the power u like and use it. some tap around the power ring will help to keep it form moving. if its a real cheap scope id drill and tap the power ring and make a stop. good luck with it.

Try zeroing it at 6x and see if it still occurs.

Im assuming this isnt a particularly expensive scope? and even if it IS, its not horribly unusually for scopes to change poi as power changes. Newer, better scopes are much better about it, and honestly I havent seen a decent scope do it since the 90 Redfields, my buddys dad had on all of their guns (they just left them set at 9) but it can still happen.
A good number of the lower end scopes, even if otherwise fully functional and pretty decent, would change poi a little depending on power. usually I sight my scopes on the highest power settings, then shoot a group of 3 shots, high, mid, low. I track where they land, and if its pretty close i call it good.
If its an inch or two different, I prefer that difference to be a a lower power setting as im more likely to use a higher power when its necessary to be the most accurate (Ive had this backfire while hunting thick areas, but generally it works ok).
If the change is REALLY significant, you can either do as Troy suggested, and just pick a functional power range and leave it set there, or replace the scope.
Ive spent a great deal of time behind cheap scopes, this IS sometimes necessary to take into account. Not all scopes from of the same make and model will be affected as well, so its hard to blatantly say THIS is a bad brand or scope type.

I find it telling that the brand name of the scope is purposefully omitted.

Shoot 2- 5 shot groups at 50 yards. One on 2 power, the other on 6 power. Is there a difference in bullet group point of impact? How much?

If it is actually parallax error, then you will be able to watch the red dot move relative to the crosshairs as you move your eye side to side while looking through the scope while keeping the magnification setting constant. The drift will be more dramatic when at higher magnification, but the images will “float” and move relative to each other based on eye position.

Zero shift with magnification increase, without that image drift as the eye moves, is NOT parallax error.

Plainly - if the red dot image does not move relative to the crosshairs because of changing eye position, it is NOT a parallax error.

I've owned half a dozen "el cheapo" scopes over the years, and regretted buying every damned one of them.

Are you planning on shooting this gun to find out what it is really doing. It sounds like you are moving your head side to side behind the rifle. If you shoot it using the cross hairs to aim at a fixed spot it would tell you if the dot or the cross hairs are really moving.

ALL scopes, even expensive ones change POI as magnification is changed. The better scopes do it less than cheap scopes. Usually not enough for most shooters to notice. I always zero at the highest magnification. And then shoot at the lowest magnification to see where the bullets impact. It is usually very close. When actually using the scope I leave it on the lowest magnification 95% of the time. If close shots are taken any difference won't be enough to cause a miss. On longer shots I always go straight to the highest magnification where I KNOW the rifle is zeroed. I never use any scope setting in between. This lessens the chances for POI to be different as magnification is changed.

Throw the laser in the trash and start shooting the rifle and see what happens. This doesn't sound like parallax to me.

Usually the magnification drift for zero is an S shape, and typically is so small it can’t be detected by the shooter. It sounds like his is one direction, and very obvious. Must be a really poor quality scope - and a defective one at that!

I’d take a stab at calling the manufacturer or reseller first. While Quality issues are rampant with low budget, imported optics, typically customer service support on warranty issues is quite good - they’re cheap enough, those companies just throw out replacements like candy at a parade.

Low quality optics shouldn’t be defective - and this is most certainly a defect. That much drift isn’t just poor design.

^ I’ve had crooked mount holes come through my shop, it never caused a scope to shift zero during zoom. I can’t fathom the geometric explanation for how crooked mount holes in a receiver could cause an erector tube to shift during zoom?

Could rings bending the tube cause it?

I've taken enough scopes apart to have an inkling how all the inside bitz work, but I don't know enough to have a solid grasp.

I would go as far to say it was probable. Zoom shift really can’t happen simply because the scope is crooked above the bore, based on the mechanical design of telescopic sight internals. A warped tube body MIGHT make sense, but even that is a pretty hard sell for the extreme shift he’s seeing, even considering an SFP.

Odd Job said:

This is exactly what could happen if your scope was mounted so that it isn't aligned with the barrel.

Click to expand...

Happens all the time when people are sighting in at different distances. When changing one axis they’re actually changing both in a diagonal pattern. Rarely see more than a clicks worth as you describe (also not discounting it being possible).

OP, not to belittle you or the scope but for anyone who might stumble across your post in the future and not quite understand why that is, I drew some crude representations on my phone (using an app my kids love for scribbling).


What happens when crosshairs aren’t aligned with bore. Adjusting either windage or elevation affects both. The drawing is extreme but demonstrates how any variance allows for diagonal movement.



When aligned correctly, adjusting windage or elevation moves only one axis at a time.

Skylerbone, may I enlarge and print your diagrams? They have such a soothing look that I’d like to hang them in my aromatherapy room interspersed between photos of LoonWulf’s feral bovine kills.

@Skylerbone is correct in how adjusting the scope windage or elevation will shift zero when the optic isn’t leveled such the vertical sub tends a line through the bore (or more precisely; the vertical plane of bullet travel).

But that’s not the same thing as what’s happening when you adjust ZOOM. The reticle and the zoom lens assembly are all contained within the erector tube, so something is very wrong if they are shifting in position to allow a significant zero drift during zoom. There is typically an S shaped shift pattern which is inherent to the imperfections in the glass and assembly, but I have never heard of an optic having that much drift as the OP describes because of this.

For zoom to shift the zero that much, the reticle assembly must be completely eccentric to the zoom assembly, and I still have a tough time figuring out the geometry of how that could happen to such a huge extent without showing OBVIOUS parallax errors (crosshairs floating across the target with changing head position and blurry reticle or target as the other is in focus).

Like I said above - I would take a run at sending it back either to the manufacturer or reseller. There’s a manufacturing flaw in the optic, regardless of brand or price, and most low grade products like that do have good warranties, at least for short terms. They’re so cheap to replace, companies don’t lose anything to back them. I’ve been through a lot of low cost optics, and had even more through my shop, this isn’t a typical low quality product issue, it’s a defective product.