I used the HHA OL-5500 for a couple seasons but decided to go back to a fixed pin sight. My only issue is that I would occasionally have some excess noise due to vibration. I'd have to go over the site and snug up the bolts. Nothing major though. I would definately buy another HHA if I were in the market for a single pin adjustable site.

And I agree with the comments about the .029 site pin. I found it too big. I would definately recommend .019.