AimPoint zero change, then back....

[The_Biased_Observer]

Anyone ever hear or see of this?

Background: rifle is zeroed, AimPoint has a lower third co-witness via a LaRue mount. Forend is a DD Lite Rail with a LMT front and rear sight. All seem tight and secure, no movement detected in setup.

Problem: Other day at the range, prior to shooting. Looking through AimPoint and irons, the dot was way high compared to the sights when using an iron sight picture. Noticeably high. Several times I took a cheek weld and the dot was high, well above the front sight where it normall is. Checked the mount, checked the forend and looked over the sights, nothing abnormal seen.

After shooting some other weapons and discounting the thing as a fluke I returned to the weapon and removed the top adjustment cap in preparation to make necessary changes. In taking a cheek weld I then noticed the dot was in the correct place.

I have since checked the weapon and tried to repeat the change, but no luck. I've thought a couple of times that maybe it was just me, and I'm perhaps due for a psyche test but I don't think so.

No changes were made to the sight via the cap, and a few shots confirmed to dot is currently zeroed.

Is it possible that the dot was "misplaced" and something then made it return to zero? It's bothering me because it is a duty rifle.

[Eric]

Especially with the irons sitting in the lower third of the Aimpoint, the dot will be noticeably higher. The position of the dot will appear to shift around, depending on your eyes alignment to the optic. As long as your point of impact isn't shifting around, you're all good.

[The Archangel]

The_Biased_Observer, maybe you and I need to go to the same psych eval because my Larue mounted Aimpoint M3 does the exact same thing. Sometimes the dot is exactly right on the tip of the front sight posts as it was zeroed and then after I take it off and put it back on (the same place), the dot is significantly higher than the post. Evrything is still tight and the gun still seems to hold it's zero. Weapon is 10.5: LMT with standard FSB, LMT rear BUIS. Maybe I should stop taking it off.

Something's definately rotten in Denmark. :o

[HolyRoller]

Pat Rogers wrote a very good article on red dots in general in SWAT mag a couple months ago. The point I took away was, and I'm paraphrasing:

IGNORE THE IRON SIGHTS. PLACE THE DOT ON THE TARGET AND SHOOT.

REALLY, IT IS THAT SIMPLE.

and just as I was thinking, shouldn't you use the iron sights to make sure that the dot is pointing to the right place, I read:

DO NOT TRY TO ALIGN THE IRON SIGHTS WITH THE DOT. PLACE THE DOT ON THE TARGET AND SHOOT.

I tried it and it works. I haven't worried my pretty little head ever since about the iron sights so long as the dot is on. If your bullets are going to the same spot as your dot, it's totally academic as to whether the dot is changing zero relative to the iron sights, or more accurately, whether YOU THINK the dot has moved relative to the iron sights.

[FJB]

No red dot sight is Parallax Free. Aimpoint sights are essentially parallax free. What that means is if you place the dot on an object further than 25 meters (better if at 100 meters) and you move your head the dot won't shift. If you place it on top of your front sight post (and you are not looking through your rear BUIS) and shift your head you'll get the perception of the dot moving. It is simply the very small amount of parallax that is inherent to the sight. Again this is true of any electronic red dot sight. Magnified optics or those with etched reticles have true parallax and the associated issues that go with them.

S/F

[ygbsm]

That's interesting about the parallax. Thanks.

My .02, if you think your sights are moving, shoot some groups.