Ahhh, that's excellent; you're already on your way there, then!

A quick look on Wikipedia provides you with pages for the various firearm manufacturers across the United States; I randomly clicked one of these and found their website, has a list of possible telephone numbers and email addresses you can contact for customer support and enquiries.

That's just one place I looked at in the last few minutes, I guess with a little more diligence you could easily locate one in your local county (or at least, your state) that you could discuss your concepts with and perhaps arrange a meeting.