Picking up a Mini 14 GB (Tactical) in a couple of days.
Already have the Ulitmak rail.

Which optics will co-witness with this setup?
Thinking about a Vortex Strikefire.

Aimpoint is not out of the question.

I don't really know if any will.  I have not read that any can anywhere.  I could be all wet though.  Those factory sights are very low.  It's not like an AR where you have that much clearance between barrel and sights.

The primary arms micro with fixed base will co-witness.  My experience hase been just low of dead of center for the co-witness with a choate front sight/ flash hider. The dot is so close to dead center that people who looked through it don't even notice.  The single blade factory ruger front sight is slightly higher than the choate and according to Ultimak an Aimpoint micro will co-witness with that. I've seen pics of people using the Bushnell micro dot too with sucess but, I can't be 100%.  The strikefire and sparc may ride too high for a co-witness.  Keep in mind that the rail will get hot from the barrel and the cheaper the scope you use the higher probability it will malfunction from the heat.  The Aimpoint is the best bet for durability but, my use of the primary arms has been fine.  I also have been mindful of the heat and let the gun cool when I feel it gets to hot.

Thanks for the replies.
According to Primary Arms they don't have a sight that will co-witness.
They said factory sights are too low.

Thinking about a 1x3 scope now.

I would think any tube style red dot that you can get a low enough mount with will work, after seeing this guys post: (you might've seen this already IDK

aimpointonminicowitnessing

This works on mine.

Well, it's not actually cowitness unless you can see the rear sight and the front sight.
That way you could use your rifle sights if the optic went down.

Looks like that guy can only see his front sight.