cowitness and lower 1/3 co witness

I have a sight mark red dot and flip up iron sights and the iron sights seem to line up perfectly with the red dot at the top of the front sight. I want to get a vortex strikefire which advertises lower 1/3 cowitness. My sight mark mount looks to be even taller than the vortex mount so how does that work? Wouldn't the shorter vortex mount make the irons go in the upper 1/3 of the optic. I'm like wtf. Here's the current setup


http://i1370.photobucket.com/albums/...psrghml9yt.jpg

cowitness and lower 1/3rd only mean how much of the viewable area of the optic is covered by the iron sights. Seeing as the red dot will follow the location of your eye (when parallax is removed), this is a physical attribute and is independent of the actual dot itself.

cowitness (aka: absolute cowitness) is when the iron sights take up the center of the optic.

lower 1/3rd is when the irons take up the lower 1/3rd of the optic.


The concept is that it's easier to view the dot when there aren't a big set of irons in the way.

You mount the red dot,( after you have satisfactorily sighted the iron sights in ) if you are using a tall mount,for a Lower 1/3 co-witness, turn on your red dot, flip up your iron sights and look through them and get a good sight picture through the irons. Then slowly adjust the dot to sit on top of the front sight post while holding the good sight picture on the irons. This is referred to as a " Pumpkin on a Post ".
Now shoot a few rounds at a target using the dot on the optics. You may need a tiny bit of adjustment, but should be pretty much on target.
and Ta Da, your red dot is sighted in at lower 1/3 co-witness.

Quote:

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Originally Posted by SideShow Bob

You mount the red dot,( after you have satisfactorily sighted the iron sights in ) if you are using a tall mount,for a Lower 1/3 co-witness, turn on your red dot, flip up your iron sights and look through them and get a good sight picture through the irons. Then slowly adjust the dot to sit on top of the front sight post while holding the good sight picture on the irons. This is referred to as a " Pumpkin on a Post ".
Now shoot a few rounds at a target using the dot on the optics. You may need a tiny bit of adjustment, but should be pretty much on target.
and Ta Da, your red dot is sighted in at lower 1/3 co-witness.

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Lolipop setup for a red dot only works with absolute co-witness, not lower 1/3.

Quote:

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Originally Posted by SideShow Bob

You mount the red dot,( after you have satisfactorily sighted the iron sights in ) if you are using a tall mount,for a Lower 1/3 co-witness, turn on your red dot, flip up your iron sights and look through them and get a good sight picture through the irons. Then slowly adjust the dot to sit on top of the front sight post while holding the good sight picture on the irons. This is referred to as a " Pumpkin on a Post ".
Now shoot a few rounds at a target using the dot on the optics. You may need a tiny bit of adjustment, but should be pretty much on target.
and Ta Da, your red dot is sighted in at lower 1/3 co-witness.

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To be clear, one must look through the iron sights to lolipop setup a red dot initial zero.

Here's a bit of reference for you, something I put together as I agonized over factory Aimpoint mounts vs Larue mounts.
https://www.ar-15.co/attachment.php?...6&d=1438050494

Quote:

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Originally Posted by SideShow Bob

You mount the red dot,( after you have satisfactorily sighted the iron sights in ) if you are using a tall mount,for a Lower 1/3 co-witness, turn on your red dot, flip up your iron sights and look through them and get a good sight picture through the irons. Then slowly adjust the dot to sit on top of the front sight post while holding the good sight picture on the irons. This is referred to as a " Pumpkin on a Post ".
Now shoot a few rounds at a target using the dot on the optics. You may need a tiny bit of adjustment, but should be pretty much on target.
and Ta Da, your red dot is sighted in at lower 1/3 co-witness.

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With the red dot sighted in, I look through the irons and I have pumpkin on a post. The red dot sits right on top of the front sight post. That's why I thought it was absolute co witness. Sight mark says it's lower 1/3 co witness and so does vortex but looking at pics, they may be the same height. So how is it that I get the pumpkin on post when looking thru iron sights?

What is the RD mount height ?

And according to Brutal, I am talking out my Arse on this,
Brutal you hurt my little feelers, I'm going to report you to the Mods ! [Tooth]

And I possibly could be, this setup for me has worked great with my EoTechs before everything was lost in the "Great Floods of 2013.......

Go shoot your setup and see how it does, if it works good, don't fix what ain't broken......

Quote:

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Originally Posted by brutal

Lolipop setup for a red dot only works with absolute co-witness, not lower 1/3.

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Huh? Explain? As SideShow Bob posted, this is exactly how all my lower 1/3rd co-witness sights get roughly zeroed. Then I flip the rear down and do my fine tuning of the red dot's zero. When I flip the rear up again and look through it, the red dot sits right on top of the front sight post. How is this not correct or workable? I've used this method on T1's, Comp M2/M3's. Eotechs and knockoff PA sights. They all zero the same and exhibit the same visual appearance. And I've confirmed the irons and the red dot have the same POA/POI. If I am doing it wrong, I'd like to know.

I just wish I could understand this. The sights are definitely in the very middle of the optic. So how is that 1/3?

I am so frustrated. How could this be lower 1/3 co witness with the sights and red dot right in the very center?