Newbie so bare with me please......

I recently purchased a RRA AR-15, it has a quad rail and also a flat top with a removable tac rail as well that has built in rear sight, now if I add an Eotech will I have to remove the the tac rail? It looks to me as if the Eotech will sit too high to use the rear or front sight with it.

The RRA removeable tactical carry handle is designed for mounting an Aimpoint according to the RRA LE rep I talked to. The EO will mount to the tac handle but it will put the EO too high for any sort of decent cheek weld and you won't be able to use the iron sights through the EO at all. If you plan to use an EO, I'd say get the Rock River Arms Dominator mount and lose the tac handle. I've got the Dominator on my RRA Entry Tactical with an EOTech mounted to it and I love this combo.

Edited to correct misinformation on my part...

The rear site is built into the tac rail though, so will I need to buy another rear sight to take it's place?

Quoted: The rear site is built into the tac rail though, so will I need to buy another rear sight to take it's place?

If you mount directly to the flat top rail you will need a rear sight of some kind that will attach behind the EO on the flat top rail. If you go with the LaRue you will need a BUIS of some kind that will mount on the back platform on the LaRue EOTech mount. If you go with the Dominator it will have a built in rear sight just like the one on the tac handle. In my opinion, folding BUIS is "cool" but just another thing that can go wrong, or add steps to switching to irons should the EO fail... And I was off base on the "absolute co-witness" statement. I had some sort of fudged up idea of what perfect co-wit was... I am correcting my misinformation in the earlier post. The Dominator actually does give a lower third co-witness, as in the sights are in the lower third of the window when aligned. Not sure how I got so bass ackwards on that issue...

A pic showing the "lower third" co-witness with the EO on the Dominator...

agree with statements above.

i had the RRA dominator mount but sold it.  For me the rear sight being fixed bugged me, so I went with a flip up rear sight instead.  it's really personal preference honestly.  Try different things out and see what you like.

RRA dominator or the yankee hill eotech mount will give a lower 1/3/ cowitness.

mounting diretly on flatop gives you absolute co-witness