Hiker, your request is a little vague.
The best I can suggest would be to go to your local sporting goods store, and look for a fishing vest. Plenty of pockets for mags/speed loaders/speed strips, and innocent looking enough to where you might look a little weird, but not threatening.
I have a basic fleece vest that I use as a cover garment for when I need an extra layer of concealment. Nothing fancy, just blends with most of my long sleeve shirts, and breaks up any printing that might be there.