Red Dot + Iron Sights

[tws3b2]

Thinking of trying a red dot sight on my PSA 5.56 carbine. Right now I'm only using iron sights. I have a red dot that's pretty old but has been used very little. I'v had for probably 15 years or so. Works perfect. It will need a riser on the carbine. I'd like to keep the iron sights on the gun. I'm just wondering how most set theirs up. Absolute co-witness
or lower 1/3?
And, Is there a way to figure how high the riser needs to be. Without a riser the dot sits a little below the top of the front sight. The iron sights are set on at 25yds.

 

[Kalashnicarolina]

Mine is cowitnessed. I use a 50 yard zero. Holosun 510

 

[Spartan]

I use offset BUIS, that easy in case of optic failure I still can manage a clear field of view.
I recommend the MagPul MPro’s.

 

[tws3b2]

This is how it's sits now. I'm thinking it needs a 0.83 riser to get it up to get the iron sights at 1/3. Then I can use iron sights as a back up.

 

[Spartan]

This is how it's sits now. I'm thinking it needs a 0.83 riser to get it up to get the iron sights at 1/3. Then I can use iron sights as a back up.

View attachment 771101

Sounds like a plan, unless you have a critical optic failure- shattered glass, caked on mud, you can remove the optic, but with offsets you are still immediately in the fight

 

[tws3b2]

Sounds like a plan, unless you have a critical optic failure- shattered glass, caked on mud, you can remove the optic, but with offsets you are still immediately in the fight

Well, I was thinking more like If my optic died I wouldn't have to get up from my rocking chair in the shade to find more batteries. I'd just switch to my iron sights and keep shooting paper targets.