Eye position for red dot / irons absolute cowitnesses

[Ruger_Ronin]

Zero your irons/back up sights at your preferred distance (another discussion here ti what’s “best”). Attach your red dot and zero it. Most likely these will be zeroed at the same distance but don’t have to be.
Assuming they are zeroed at the same distance then absolute or 1/3 cowitness are you to you.
If you absolute co witness then you will typically have a somewhat repeatable sight picture. If you do all things textbook everything will line up perfectly. That is not required though and as others have said if your dot is on target you are gtg. Often you may be unable to get in a perfect position so imagine aiming over a wall while standing on one leg. So long as your dot is on target you should be gtg.
Fixed irons compromise the fov when using the red dot but you learn to just ignore them pretty fast and they are always there if you need them.
QD mounted rds can just be removed in the ev nt the rds fails. Taking off and on you would have to confirm the return to zero but quality qd will be within 1/2 moa.
It’s a journey and what works for you and your needs trumps all.
Just when you figure it out you will want to look into 45 degree offset irons or mrds and a LPVO or magnifier for your rds.
Plenty of great info in this thread already and just adding my two cents.

Excellent advice.

Zero the irons and RDS independently. Forget "lining up" everything perfectly. You'll be using one or the other, not ICW each other.

FWIW, I would think about flip irons for the rear set. Otherwise you'll have quite a busy sight picture. The A2 will fade out almost unnoticeable when using the dot, especially if you put on a magnifier

 

[Ruger_Ronin]

I have one AR with a Sig Whiskey 3 W/Hellfire reticle mounted on it that I can use like a red dot with the lens cover down.

I have gone through several optics config's I can't keep track. Finally settled on lpvo w/ canted reflex. My favorite/most successful to date. (Yes, there are BUIS too)

 

[Gabriel]

Excellent advice.

Zero the irons and RDS independently. Forget "lining up" everything perfectly. You'll be using one or the other, not ICW each other.

FWIW, I would think about flip irons for the rear set. Otherwise you'll have quite a busy sight picture. The A2 will fade out almost unnoticeable when using the dot, especially if you put on a magnifier

With cowitness red dots, I normally recommend sighting in the irons first. Then I have everyone move the red dot to the tip of the front sight as they look down the irons. Once that is done, I have everyone flip the irons down (if possible) and we sight in the dots. Doing it this way gets the dots close so we aren't messing around with stuff that's eighteen inches off from the get go.

I have one rifle with fixed irons and a red dot. If you use the red dot as intended (target focus) I don't notice the sight picture being busy at all. It's just a dot like any other rifle set up.

 

[Ruger_Ronin]

With cowitness red dots, I normally recommend sighting in the irons first. Then I have everyone move the red dot to the tip of the front sight as they look down the irons. Once that is done, I have everyone flip the irons down (if possible) and we sight in the dots. Doing it this way gets the dots close so we aren't messing around with stuff that's eighteen inches off from the get go.

I have one rifle with fixed irons and a red dot. If you use the red dot as intended (target focus) I don't notice the sight picture being busy at all. It's just a dot like any other rifle set up.

Agreed to the "lollipop" method of initial sighting. I was referring to, not necessarily OP, but guys trying to get everything to be perfectly lined up and zeroed down a center line

I've heard fellers before..."my dot is on but to the (side) edge of my front post! What gives!"

 

[Gabriel]

Agreed to the "lollipop" method of initial sighting. I was referring to, not necessarily OP, but guys trying to get everything to be perfectly lined up and zeroed down a center line

I've heard fellers before..."my dot is on but to the (side) edge of my front post! What gives!"

Yeah, even if something is advertised as being cowitness, there are a lot of variables involved. You are trying to line up parts from multiple manufacturers (maybe different front and rear sight brands, an optic brand, a riser brand, maybe a different hand guard brand than the upper the rear sight and optic/riser are mounted to) with different tolerances. They will almost never completely line up.

I was at the range with some officers from a neighboring department earlier this year and their armorer just moved their dots to line up with the irons (and never fired a single round to confirm) and they've been carrying patrol rifles for quite a while like that not knowing there could be an issue at all. They were also lining up the front sight and red dot while shooting and ignoring the rear sight all together. We go them squared away, but I think the rest of their PD is still carrying rifles that aren't sighted in.

 

[Ruger_Ronin]

Yeah, even if something is advertised as being cowitness, there are a lot of variables involved. You are trying to line up parts from multiple manufacturers (maybe different front and rear sight brands, an optic brand, a riser brand, maybe a different hand guard brand than the upper the rear sight and optic/riser are mounted to) with different tolerances. They will almost never completely line up.

I was at the range with some officers from a neighboring department earlier this year and their armorer just moved their dots to line up with the irons (and never fired a single round to confirm) and they've been carrying patrol rifles for quite a while like that not knowing there could be an issue at all. They were also lining up the front sight and red dot while shooting and ignoring the rear sight all together. We go them squared away, but I think the rest of their PD is still carrying rifles that aren't sighted in.

Well that's less than reassuring.