A few users pointed this out, and I did a quick test at 50 yards and moved on. I did not put much time into it, nor did I try super hard to shoot tight groups. I was told the shift was on the order of 10 MOA, and I figured either it was...or it wasn't, so I shot some quick and dirty groups and it wasn't, so I figured it at nil.

It's not 'nil. It is 4 MOA. I have now tested it at 25, 50, and 100 yards. The groups at 100 yards are, as one would imagine, not the prettiest (about 4" across with cheap 55gr FMJ), but at 25 yards it is a VERY clear picture of the shift. Same at 50, and it extrapolates out to 4 MOA at both 25 and 50 yards.

When you shoot with the T2, it shifts the group up and to the left on a 45* diagonal by 4 MOA, as best I can tell.



As a datapoint, as many will ask "Does the T1 do it?" I found this on TOS, in a completely unrelated discussion (red highlight added):

You don't say!!!



Three separate T-2's here, all replaced by aimpoint, damn near same results as yours.  Mine were between 4-6 moa shifts depending on the T-2.

T1s are all I run.

This is exactly why.  Told aimpoint reps about this problem, seemed as if I got nowhere despite repeatable results.  I even insulted Andrew Bobro by asking him to replace a mount he sent me hoping desperately that aimpoint wouldn't give me 3 turds, and maybe it was my mount.  It wasnt the mount, the mount was, as all my other Bobro mounts....flawless.

Wanna see something funky?

Set a visible laser to your irons, without the T-2 in place.  Then....put the T-2 on your rifle and look where the laser is now, relative to your irons.  Leave the T-2 off.

Your laser won't be in the same spot relative to your irons.  Say hello to your optical shift.

Test 2.  Zero your irons with the optic off the rifle.  Now, put the optic on your rifle, zero it.  Now, deploy your irons and cowitness them.  They won't line up, I promise.

Viola.  Aimpoint, your T-2 blows, and I told you about this months ago.

Weird. I get that same effect using ANY RDS combined with a co witness rear sight. I've since switched to co witness rear FOLD down and have no such issues. But if I ever flip the rear up.. sure enough the dot is "off". Something about using dual plane focus sights, combined with RDS, does not register properly in my brain (and results in "off" dot). Same thing happens when I try to use 1/3 co witness.
So long as I use a fold down rear... I'm GTG. So that's what I stick with (absolute w/ Co witness flip down rear).

The T2 is durable enough that I'm fine with this. If the dot is dead, I presume the window is also unusable or covered in mud and the T2 must be removed anyway. Zero without it. Keep it on a qd mount.

Also, that being said, it's a predictable shift. You know how at 200m you aim for the shoulder on the magazine-side when you're shooting with the weapon canted, as in roll-over prone? Do the same thing, here.

It is not a big deal or a problem. IT IS something to be aware of, though.

Color me stupid, but I don't understand the issue here. How can the t2 cause a shift in the irons.

Because your eye sees the rear sight with nothing between it but air. The front sight is the same---unless you have an optic, in this case, the T2, between it and your eye.

The nature of the T2 is to reflect light at an angle, so that the "dot" can be "bounced" off of the front lens, and back into your eye. To do this, the dot is shone at an angle (from the bottom right) of the optic housing onto the front lens (center), and is then bounced STRAIGHT back into your eye. There is a good bit of bending going on, here! You will note that the deviation of the shots follows a 45* diagonal. Very similar to the angle the "dot" is bounced at...

So what is happening, is your eye's perception of the rear sight does not change, T2 or not. However, where the front sight "is", DOES change. Like sticking a pencil in water.

To clarify (sorry, I'm just not very smart) does this happen ONLY when trying to cowitness, or does it happen when using the T2 alone?

Any time the T2 distorts the light between the FSP and your rear sight. I turned it completely off for this test. Dot was gone.

Now I understand. Yes, that is a huge issue. I have not heard about this until now, perhaps I will shift my attention away from the T2 and consider hanging onto my Comp M4

 

I would verify if your Comp M4 doesn't do it as well. They both function on the same principal.

That said, a 4 MOA shift that is predictable is a non-issue in my book. You zero your irons with, or without the T2 in place, and remember.

So, if you have stowed/no BUIS, there's no problem?

If you don't have iron sights, then their zero can't shift due to interference, yes, that does sound logical...

What am I missing here?

Can't  you zero your irons looking THROUGH the RDS and be done with it? Only if you removed the RDS and then attempt to use the irons you would have the problem, correct?

Correct. Zeroed through T2, no problem when shooting through T2. T2 window gets broken or fogged/iced/mudded up and you remove T2, now you have to account for POI shift.

Its funny I posted a thread about not liking RDS, I was ok with a t1, but wanted to try out the t2, I also gave an eotech a try. I took both out to the range and pretty much hated them both.

I had planned to put a an accupower on the rifle, but an opportunity to get back into a t1 came up. Reshot the rifle this weekend with a t1, and I love RDS again. I got a really weird parallax thing with the t2, and the smaller rear circle messed with my ability to use both eyes open. That and the fact I never saw a true round image when looking through it was really discouraging. That and like this thread I noticed a poi shift with my irons.

Glad to be back with a t1.

The T2 works the same as the T1 for me, except magnified, in which case the T2 is far better. I did not test T1 for zero shift of irons, but others say that it has it, as well. To what degree, I do not know.

Everyone's eyes are different.

12_guage,

Another great informative post. I just recently received a T2 and Bobro mount (based on your recommendation). This explains the trouble I was have the other day trying to site everything in. I am still very new to this.

Interdasting.  I don't think I am going to be able to sleep tonight..................

Its weird, I had my irons previously sighted in, when I got the t2 I adjusted the dot to my irons, and like the poster above seemed to always be chasing a 3-4 moa shift. Put the new t1 on, every thing lines up. And stays that way!

I will agree with a magnifier the t2 has a beautiful round dot. But I felt the need for a magnifier to not be really high on my list when I shot better without it

This is still new to me, but if i understand correctly, if i zero my irons and then zero my dot to my irons, my dot will not his POA?

Keep your Aimpoint in a LaRue or Bobro mount.  
If it shits the bed, pop it off, drop it in a pocket, and keep shooting with your irons that you zeroed without the optic mounted.  

I don't see how this is an issue.  In ten years I've fucked up two buis and NO Aimpoints.

Its an issue because its fucking stupid and a terrible oversight by aimpoint.  If my primary arms red dot sights can look OK through a magnifier and not cause my irons to be off, I'm sure aimpoint can figure it out too.

Its especially a problem since they deny the problem exists, and don't tell you about it so you have no idea how to compensate.  I'm pretty sure John Enloe of aimpoint thought I out of my mind, he was absolutely baffled and convinced this issue didnt exist when I was dealing directly with him, but to his credit, he kept sending me new aimpoints figuring maybe something was wrong with the ones I got.  I went through 3, realized this WAS a flaw of the T-2, and gave up and went back to my T-1's.  He said, paraphrasing of course, that its not possible for one to zero the irons to the dot, remove the sight, and have the irons be off.  

My T-1, Pro, M2, M3, M4 etc do not do this to this extreme.  

I have been able to set the irons to a zeroed red dot, and my irons have been on.

If you zero your irons to the dot on the T-2, you're going to have to crank the rear sight all the way over, assuming that the irons zeroed relatively centered prior to mounting the T-2.  This works fine, if you want a jacked up rear sight, and are only going to use your irons while looking through the T-2.  Take the T-2 off, and your irons are off.

Flip up iron sights are emergency sights.  I don't want to be forced to use a QD mount if I don't want to.  I want to be able to use my irons with the sight in place, or without it in place and not have to worry.

That is the whole point of a good zero mag sight.  Durability, reliability, simplicity.  Making my iron sights not work is a pretty stupid problem to have.

Brought this issue up on this forum immediately when I discovered it, which was right when the T-2 was first released.  Got the same looks from people here as I did from John.  Glad to see so many people here are concerned about fundamentals of shooting with iron sights, that its just now been confirmed by another member

This^^^

That doesn't mean Aimpoint shouldn't address the issues but it's not that big of a deal if your aware of the issue and zero your irons properly instead of trying to just line them up with your dot. I never run my rds and irons together. It's one or the other.

Wow,this is a pretty big discovery.

I have never had a problem with my T1 lining up my irons with a zeroed red dot and being off.


Aimpoint better look into this as i wont buy a T2 at any price unless they recall or fix this problem.


Its a flaw if you have to use a QD mount, i like to use DD fixed mounts so a T2 is out of the question for me.Thanks for the info

I think it's an artifact of the lens being canted in the housing.  

Whatever they did to alleviate the blue color and parallax of the T-1 made the image of the irons shift more in the T-2.

The T-2 is a better optic than the T-1.  I've used both.  I used a T-1 for two years, I've used the Comp series longer than that.  

The T-2 has the optical clarity of the comp series, with the compactness of the T-1.  Not to mention better brightness settings than the T-1 which is always either too dim, or too bright.  

For people who use their shit in a manner that is realistic, it's a non-issue.  They're back-up irons that are damn near useless through a Micro in a lower 1/3 mount anyway.  Try using 'em in the dark with a white light through a T-1 and see how good you shoot.  You can't even use the sights like that.  I've tried it.  

This.

I have never considered using my irons LOOKING THROUGH my RDS. When ever I check my irons, I remove all the optics. I am totally OCD but this POI shift is not an issue to me. I have never considered trying to use my irons through my Swaro or Kahles either. I much prefer the T2, especially using a 3X since the dot is crisp, due to the slightly off-angle glass.

Please help me understand why someone would use their irons looking through an optic. Somebody....

We get it.  We're not going to convince you its an issue just like you won't convince me it isn't.

I could explain it, but just like you posting here exclaiming not an issue, would be a total waste of time.

Exactly. Think of theT2 as a Kahles stuck on 1X, with less optical clarity but much longer battery life.

Can the issue be worked around by installing the rear BUIS in front of the Aimpoint?

Interesting thought, but then, it might distort things even worse. Who knows?

Time to get some offset irons, if you're running this setup and see yourself making shots with your BUIS.

Well, it certainly will distort what you're seeing through the optic.  But that distortion is constant.  So while it will distort what you see through the irons, it will distort the view of the irons in the same manner.  So if you sight your irons correctly, you'll hit the same spot.  But your EYEBALL will be in a different position.

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When does anyone actually use irons when they have an Aimpoint anyway???

Aside from flipping 'em up every now and to see how bad they suck, they never get used.  

I don't even have buis anymore.   The past ten years with Aimponts have showed me that they don't just die, and they're tougher than most any buis.  Especially the Micros.

For one, it's faster. Another is that, since you're not removing it, you don't lose your zero just because of a dead battery. It's also the reason 1/3 is popular. Personally, I don't understand why someone WOULD remove it.