I had a chance to use the FA mode yesterday. We were hunting a CW Calvary camp. I hit a spot that was full of iron. Mostly square nails. I decided to switch over to the FA mode. It was unbelievable. I was getting solid grunts (2F). I switched to FA and immediate got a solid high tone reading 48-49. I dug it and there was so much iron I couldn't hardly find it w my pinpointer. But it was a shotgun hull buried in all that iron. It picked it up very cleanly. I found two hulls like that in the middle of that iron w my 11" coil. I can't imagine how good it would be w the 5" coil.