Lack of a (C) next to an image does not even remotely mean it's not a copyrighted image. Additionally, a Google image search pulls up every image they (Google) can find on that search topic, with copyright info often being cropped off the images.
Just because every single pistol in your local gun shop doesn't explicitly say "do not steal" on it doesn't mean you can walk out the door with it without paying. While the internet has made IP theft far easier than it ever has been before, it's still very much theft.