Reticle vs irons -- windage issue is driving me mad

[DaBigBR]

In addition to the things mentioned, I would suggest against worrying about the relationship between zeroed irons and a zeroed red dot. There are a lot of factors at play and while slaving them as a starting point (particularly if you know your irons are good) might help, you may end up with a difference in relative position to have each sight system "zeroed."

[Binkius]

I've been wrestling with a similar problem and found a solution.

The problem is when I look at the red dot, it doesn't co-witness. The reason it doesn't co-witness is that I'm looking at the red dot. I'm supposed to be looking at the target. The red dot is designed for target focus, not dot focus.

I know my iron sights are PoA = PoI, so the solution is to adjust the red dot so that when I'm focused on the front sight (where PoA = PoI) the red dot has perfect co-witness. Now the dot has the same PoI as the iron sights. Don't just line up the three iron sights. Actually focus on the front sight. If all you do is compare the location of the red dot with the three sight posts, you are focusing on the plane of the red dot, not the front sight.

When looking (focusing) at the red dot, it won't co-witness, but when I focus at the target, the red dot will co-witness because the red dot has been zero'd to the same PoI as the iron sights. From focusing on the red dot to focusing on the front sight/target, I can actually watch the red dot move (by itself) from off-center to perfect co-witness as my brain figures out the sight picture/focal plane. For practice focusing, I've taped over the red-dot lens to force my eyes to focus on the target. Your brain will melt the two images together and you will see the red dot on the target. If you can't see the red dot on the target, you're focusing on the dot and not the target.

I think this is heavily impacted by eye sight, how each individual's eyes and brain process sight picture, the optic and sight radius of the pistol. I have a Holosun 507K that co-witnesses no matter if I focus on the dot or the target. My Trijicon SRO's have a little difference while my Holosun 507C's have a lot of difference. All will perfectly co-witness with the same PoI if I focus on the front sight. I'm in my 50's, have progressive lenses and am cross-eye dominant. Lots of problems.

I think this is also why red dots seem to co-witness easier on rifles. With a rifle's long sight radius, you are usually focusing on the front sight PoA = PoI, where a properly zero'd red dot should be. On a pistol with a short sight radius, it's easier to focus on the dot instead of the front sight.

Also ignore the cheap bore-sighter. Those are to make sure you don't miss the entire backstop on your first shot. Useless for fine targeting.

[Binkius]

This drove me nuts until I figured out what my eyes were doing. I'm getting groups (10 yards), but in different places.

Focusing on the dot gives one PoI and focusing on the target gives another PoI.

I think this phenomenon is highly dependent on the individual.