I recently built a 12.5" AR15 just for the sole purpose of running irons only and keeping myself proficient in the use of them. I settled on Scalarworks Peak iron sights (fixed) and they did not disapoint. I was shocked at just how fast they are at target acquistion, I bang steel with them from 3-75 yards for the most part and on freshly painted steel the groups are pretty tight for moving and shooting. I have an 8" round thats about 110 yards out along a road and using a tree for support I can consistantly hit it. I am super impressed with them!
https://scalarworks.com/iron-sights/