Primary arms micro dot works well with the ultimak
You should get a good 1/3 co-witness with those irons as well. I have a Sparc 2 on my Ultimak and I have a lower co-witness, less than 1/3, I would say, but it works. It's a good dot but a little bigger and heavier than the PA micro. A friend and fellow ODT'er introduced me to his Ultimak and PA micro a couple years ago and it was a dang good combo.