What did I buy?

[David]

Originally Posted by Marcus

I have sold like 20 copies of the book. Anyway, the book only has guns in it. None of the pictures posted on this forum are in the book.

Marcus, it wouldn't matter if you had only sold just one book, it is still a commercial site as its main purpose is to sell more books. It doesn't matter that none of these photos are in the book. You are certainly aware that there are many collectors of antique firearms on these forums and that you have an audience for selling your book here. An ad for this book would, of course, be most welcome in the Swap Forum if you have not already placed one there.
As Andrew has pointed out, placing your the website on these images as a watermark is an advertisement. It does not protect copyright. The law states that any image you create is automatically copyrighted, but if you would like to ensure that your images have attribution a more proper manner of doing that would be to place "©Marcus _______ 2014" in place of your web address. But even that will not ensure anything since anyone with the least bit of photoshop knowledge can either crop out you watermark or remove it in a single key stroke as i have done with the example below.