I have struggled with the same problem.
I called Smith and spoke to one of the tech guys regarding this issue:
They are supposed to be POA/POI at 5 yards or so they will all shoot 6" high or so at 25 yards. It was never their intention for the irons to be co-witness with the dot and they are supposed to be low in the window and used as "emergency style sights". S&W only makes (1) standard rear sight height (.405) for the CORE and (2) front sight heights (the standard being .320), the other front sight is a shorter one for when you are shooting LOW. The only way to get co-witness sights for the CORE is to order a set from Dawson.
FYI for most CORE models, the proper sight height from Dawson is .360, however their fixed "co-witness carry" comes with the same height as the factory S&W CORE (.320) which will lead to the same problem, so you will have to order each sight separately.
You can also opt to order the set and call them and ask them to replace the front with the proper height via their guarantee.