Weird Aimpoint T1 phenomenon

[Doc Safari]

OP: I have trouble getting ANYTHING to "lollipop" with ANY Aimpoint T1, H1, or R1 (tried all three), except for the LaRue LT103 mount and/or the LMT M16A2 style rear sight. Yes, it's important to me for the red dot to rest on the front sight post, and since it's my rifle, that's how I'm going to have it.

People tell me it's "just me" the way I hold my head or something (technique ain't my strong suit).

To make a long story short: try a different BUIS and you may find the problem solves itself.

It became such an aggravation to me that I use a folding rear sight now and keep it in the "down" position.

[aguila327]

What difference does it make?

If my irons hit POA/POI at my chosen zero distance, then they're good to go.

Likewise if my red dot hits POA/POI at my chosen zero distance, it is good to go as well.

Why mess with it past that?

THIS!

When did co-witness become defined as the red dot riding atop the front sight post.

Just make sure the sights are usable through the red dot sight and your set.

Sent from my SCH-I535 using Tapatalk 2

[dmaxfireman]

What difference does it make?

If my irons hit POA/POI at my chosen zero distance, then they're good to go.

Likewise if my red dot hits POA/POI at my chosen zero distance, it is good to go as well.

Why mess with it past that?

Not disputing that if it works separately and he is happy then leave it alone.

But if he views the dot through the rear aperture, would be interesting to see which is dialed in. So with the red dot and rear sight both in play, shoot a group off the front sight post and group off the dot. Which is on target and which is off.

[Ironman8]

What difference does it make?

If my irons hit POA/POI at my chosen zero distance, then they're good to go.

Likewise if my red dot hits POA/POI at my chosen zero distance, it is good to go as well.

Why mess with it past that?

Because it helps to have the dot centered on the front sight post and be able to confim zero just by flipping up the BUIS and seeing if they line up...perhaps after bumping your red dot for example...and I'm talking about AFTER they have both been confirmed for POA/POI.

Yes this can still be done if the dot is off center so long as you remember exactly where the dot is supposed to be in the sight picture, but depending on where it is, it may be harder to do so vs. it being centered.

That said, I've never had a problem with my M3 and PRO lining up on the front sight post. I would tend to agree that it has something to do with an inconsistent cheek weld...but that's hard to diagnose from behind a keyboard.

[dmaxfireman]

Just went into my safe and verified my t1 and m4s both line up nicely with the irons.

[JSantoro]

First, the idea that your dot (presuming that you're zeroing POA/POI at the same distance on both Irons and RDS) MUST rest atop your front sight post is false.

I've got an H1 on an LT751, stuck on a Noveske 14.5" gun. If I get sight alignment/picture with the irons, my dot's low and right, almost exactly like your first illustration. Irons and RDS are zeroed exactly the same and print the same, so you'd have to pay me to care less about how it LOOKS, because I'd be willing to bet my eyeteeth that all it means is that my FF forend isn't quite perfectly true, which puts my front BUIS just a skosh out of plane with the optic. NOT substantive, as the gun shoots straight, and only one way among many that could explain a dot being somewhere besides the front sight post, yet the gun STILL being correctly co-witnessed.

Anybody thinking "I've never seen it NOT line up....," that's almost certainly completely factual: You've never SEEN it. One's experience isn't invalid....it's the conclusion that's jacked-up.

Second, we're talking about non-AR-pattern guns, here. That's gonna become important in a moment....

Third, even if the desired endstate was to achieve a certain cosmetic goal...which it's not..., you're assuming that the mount you're using is meant to provide the cosmetic condition you wish in the first place. You said you're using the Micro low mount variant. From the LaRue product description of the LT661 (emphasis mine):

Short Shotgun, PS90 & AK (LT661)
QD Mount for Aimpoint Micro Sight. Gets the Micro down low to use on Shotguns, PS90's and AK's

No mention of co-witness, at all. Only that it mounts a Micro lower on a rail than the 660 and 660HK (each of which identify both type of guns and type of co-witness, because each of which is designed to provide for it).

Heed The Rat.

[mattj]

I don't know if this is what is happening, but here's a theory....

If you happen to have astigmatism, you could be zeroing the red dot based on the apparent (distorted because of your vision) center of the dot...

Looking through a peephole such as a rear sight has the effect of "correcting" astigmatism for things like a dot sight.

So if you have astigmatism you may be effectively seeing different dots depending on whether or not you are viewing through the rear sight, which could explain why you don't get the "lollipop".

[Ironman8]

because I'd be willing to bet my eyeteeth that all it means is that my FF forend isn't quite perfectly true, which puts my front BUIS just a skosh out of plane with the optic. NOT substantive, as the gun shoots straight, and only one way among many that could explain a dot being somewhere besides the front sight post, yet the gun STILL being correctly co-witnessed.

Anybody thinking "I've never seen it NOT line up....," that's almost certainly completely factual: You've never SEEN it. One's experience isn't invalid....it's the conclusion that's jacked-up.

This made me realize that I've always used a VIS upper, so it would make sense for mine to always line up. I'm about to go zero my MUR/NSR that just replaced my VIS and may very well see this happen. Like I said above though, it will still work.

[GH41]

Has anyone even looked at the gun he is having this problem?? I have no idea how tall or short his irons are. He isn't having problems with an M4! GH

[Failure2Stop]

Far more often the dot does not perfectly sit atop the front sight post than does, in my experience and observation of a few thousand setups.

Also, since you zeroed your irons without the glass of the T1 between the sights, once you put it there you induced some degree of parallax.

I believe that both systems SHOULD be zeroed independently, as in the event of an optic failure you might need to ditch the optic and rely on the "pure" iron zero. Of course, checking POI shift through the glass with the dot off is pretty important as well.