Weird Aimpoint T1 phenomenon

[Ironman8]

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.

Do you think the parallax is enough to worry about, given that most shooters/setups with a RDS will be about 3MOA? My thought is that it wouldn't be, but you would know better.

[Dano5326]

Ah.. wow.. irons and red dot clearly not in the same plane/s. Next question.

"exact" co-witness on an AR.. 1.5" mount matching sight heights
"lower 1/3" co-witness.. mount higher

whatever vertical and horizontal offset is involved with unknown aimpoint mount and sights on afore mentioned FN2000... who knows?

[JSantoro]

Ironman, admittedly unlikely, but also not outside the realm of possibility. Such devices are only as parallax-free as they can be made to be.

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

Yep, that was my 2nd point, of three.

We're somewhat off the edge of the map because it's a completely different gun than an AR configuration, so there may be an element of trying to shoehorn facts to fit a conclusion, instead of using facts to derive one.

[tysonf]

G19A3
I'm running a Daniel defense V1 with a Micro t-1 and I have the exact same problem. I've zeroed both independently. But when it comes to lower third witnessing it's just like you said the red dot to the top right. And the mount I'm using is the DD micro t1 mount. I'm gonna try to cowitness zero again this week - we'll see it'll be the fifth time I've tried.

I am wondering if it's cheek weld. Or if I'm getting lazy at some point in the process. But last time I had two army buddies helping me and still it's off to the right. So.....?


Chairborne Stranger

[G19A3]

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

Did you zero the irons and THEN mount your RDS and mechanically zero the red dot aiming point to "match" to your irons without firing live rounds?

OR did you zero the irons and THEN mount your RDS and independently fire live rounds to zero the red dot aiming point independent of the irons?

[G19A3]

G19A3
I'm running a Daniel defense V1 with a Micro t-1 and I have the exact same problem. I've zeroed both independently. But when it comes to lower third witnessing it's just like you said the red dot to the top right. And the mount I'm using is the DD micro t1 mount. I'm gonna try to cowitness zero again this week - we'll see it'll be the fifth time I've tried.

I am wondering if it's cheek weld. Or if I'm getting lazy at some point in the process. But last time I had two army buddies helping me and still it's off to the right. So.....?

Any updates Chairborne Stranger?

[wahoo95]

The dot and sight post aren't gonna line up most times if you truly zero them independently. Simple fact is what you see thru the red dot is different than what you see thru irons/aperture. Lining up a single dot is different than having to align two sights to a target. This is one of the reasons I can sight in a rifles irons then the next guy shoot it and it not be perfectly zero'd. Different people align differently. The mechanical zero of the rifle may be the same but different peoples view thru the sight or optic is different.

[tysonf]

I have the micro mounted. Turned it off. Zeroed irons. Then zeroes red dot. Then went back to look though irons to see red dot for true cowitness and it was off to the low right - the red dot. My issue is that this never an issue with my army issue rifle from my arms room. That how we do it. Irons, redd to, then both together.

I haven't gotten back to a range. Hopefully going next weekend bf some buddies redeploy.

[G19A3]

I have the micro mounted. Turned it off. Zeroed irons. Then zeroes red dot. Then went back to look though irons to see red dot for true cowitness and it was off to the low right - the red dot. My issue is that this never an issue with my army issue rifle from my arms room. That how we do it. Irons, redd to, then both together.

I haven't gotten back to a range. Hopefully going next weekend bf some buddies redeploy.

The problem is almost everyone has a different answer on how they zero. Some mount the RDS assembly, then zero both RDS & irons SEPARATELY. The irons being sighted through the RDS (red dot turned on/off/whatever).


Independent zero to me means....Zero irons with NO RDS mounted at all. My reasoning is if the RDS goes tits up (failed batt/broken lens/muddied lens/etc.), I use the Quick Detach feature on the mount and take the whole RDS assembly off and now use the irons exclusively (ala regular A2 fixed sights). The irons should be POA/POI because that was how they were zero'd. Now, I fold down the BUIS and mount the RDS assembly. Zero RDS assembly with NO iron sight in view. Upon completion, flip up BUIS. Shoulder the rifle and the red dot is NOT sitting centered nor on top of the front sight post.


Why would I use irons THROUGH a failed RDS? (ONLY if there was no time to QD)
Why would I use irons THROUGH a functioning RDS?


I think my conclusion is viewing the zero'd irons THROUGH two 'imperfect "non-Hubble quality" glass' pieces of the RDS creates a "refracted" iron sight picture. Is this issue called parallax? I dunno.

I also think (as viewed with rifle shouldered) the further the irons are from the circular center of the RDS (i.e. lower third co-witness) the worst it gets. In other words, if an absolute straight line can be drawn from the center of the rear sight aperture....thru the center of the RDS (both pieces of glass)....thru to the top center of the iron front sight post, this offset phenomenon would be minimized, but not entirely gone.(?) **** if I know as all my mounts are lower third co-witness and all have the same phenomenon. Including my four AR's with RDS mounted as far forward on the upper receiver proper. When my ARs are shouldered, the actual position of the RDS is a lot closer to my eye (referenced to the rifle lenghtwise) than the waaay forward mounting setup I have on my FS2000's. Yet the phenomenon occurs the same with AR's and FS2000's.

Like I said **** if I know. That's why I figured I would ask here. Either way, I'm only off 1.5" high left at 50yds, if I have no time to QD and need to shoot through the RDS.

[tysonf]

The reason I find it perplexing is that after many years shooting and zeroing and doing range time with my army issue colt - if I go through the exact same steps we use in the army my crap doesn't line up. Never have this issue with my work gun.
Also, we don't really use quick detach stuff. In fact we tie everything on our weapons down with gutted 550 cord. The way is was put to me by a tier one teacher is that often even when the glass breaks on an aim point the red dot still works. And if that fails you can just aim through the busted glass etc. Now Paul Howe I think has a different take on that since in the first moments of the gothic serpent operation his optic was broken and he couldn't get it off which I think I remember hearing him say was a problem.