If you still want to use an iron sight set up, then try a ghost peep, with a small Firesight front sight rod(blaze orange). Even with my poor eyesight, I can still get 4 inch groups at 100 yards with this.
Also, believe it or not, it is much easier for me to get tight groups with iron sights at 50 yards, than 25 yards. I don't know why. Maybe its because that bulls eye is just too big at 25 yards, or maybe the target is so close that I automatically keep trying to focus my eyes on it (instead of the front blade). So, perhaps you should try a 1 inch, or 1.5 inch bulls eye at 50 yards, on plain white paper, and you may be surprised how much your groups shrink.
Best,
Mannyrock