RDS: Co-Witness or Lower 1/3 Co-Witness... your thoughts?

[Rotorhead84]

I like lower 1/3rd

[misanthropist]

I like lower third BUT:

Something I never see mentioned anywhere is that some popular RDSs can actually interfere with some popular sights.

For example, I have a T1 on a DD mount and Troy fixed sights. The emitter on the T1, at least if you run it up at the front of the receiver like most do, clearly obscures part of the rear aperture on the Troy if you have it on the large aperture.

It's not a huge issue, but it does distort the shape of the aperture slightly so it's going to alter your POA. On the small aperture it's hard to tell if it's in the way at all, but it's got to be close, for sure. Granted, any effect it has is going to be pretty subtle, but depending on the level of precision you demand from your irons...

Anyway I thought I'd mention it since I've literally never seen it addressed anywhere, in 10+ years of talking ARs on the internet.

[TF82]

^ That! My Eotech EXPS-2 mounted all the way forward did this very slightly with my Magpul MBUS Pro sights. It cut very slightly into the bottom of the aperture keeping it from being circular, even the small one and it ****ed me all up to the point that I could barely get a good enough group to consider them zeroed at 50 yards. The funny thing is that I didn't even notice it until I started shooting it. I ended up moving things around and now those are under a scope and I put fixed irons with the Eotech. The Eotech is now back in Ann Arbor and as I wait for my refund I'm now leaning toward an Aimpoint with absolute cowitness and fold down sights again.