In Georgia, you don't have to tell. If I stop you for a traffic violation, I assume that you are armed. It doesn't bother me if you are because I am too. Just keep both hands in plain sight, speak politely and move kinda slow, and it all works out well. I like the driver to tell me if I have him/her get out of the car for any reason, if he/she is carrying on their body...just keeps my blood pressure normal. From a libertarian view, it ain't any of my business. Rookies get kind of silly about it, but there is no good way to tell a veteran cop from a rookie one.