I have hit Ole Gray's RBZ irons and I could not hit the 4 and 5 iron for the life of me to start with. I took them to the driving range at his course and hit about 15 balls with each and began stripeing them straight and long. They take a little getting used to and then they are pretty awesome like the rest of the RBZ irons. Good luck bjz, keep us posted on your progress.
I had the same problem. I removed them and replaced them with my RAC OS 4i and a 3 hybrid. The RBZ 5i is the same loft as the RAC 4i.