I'm placing this here instead of in "Links" due to it being more reference than offering anything merchantile.
This is a fun site that appears to have been put together by people who actually know and enjoy firearms, and who spend wa-a-a-ay too much time pausing and studying individual frames of movies. I've gone through their list of western movies and they confirm a number of inaccuracies in various films that I spotted myself, as well as pointing out quite a few I missed over the years.
Check it out and enjoy.
http://www.imfdb.org/wiki/Main_Page