With all the blatant AR/AK posts popping in the FS forum, I'm sure it would be easier to find rebel rousers there than at the local range!
That said, I took the extra step of photocopying FA-10s for the AG-unfriendly rifles I tend to bring to the range. Why? Because I'm more informed than someone who might ask questions, and proof of registration prior to this summer eliminates the need to defend my interpretation of an interpretation of a law that seems to be fluid at best! "This? I bought it three years ago, and here's proof."
I follow the same philosophy with magazines. AK? 7.62 are from China, banned from import almost 30 years ago. 5.45? East German, because East Germany only existed until 1990. AR? I pencil in a few words on the floor plates of the ones I bring to the range. "External date", "Internal date", "Manufacturer out of business before 1993". Again, I'm proving that I know the law and follow the law.