Eric,
Gerard Henrotin's e-book Luger Mechanical features would provide information for you with graphics in addition to the written explanation, so once again I'll recommend spending what might be the best $7.99 you have ever spent! This book is replete with history--including the thinking behind each system's incorporation--along with excellent explanations of the mechanical aspects of the different features such as the sear safety, mag safety, etc. The illustrations assist, when paired with the descriptions, in understanding all this stuff. And to save you a trip to our site's front page, where M. Henrotin's rendition of the firing sequence of the Luger is animated, along with a link to his e-book site, here's the direct link to the particular book in question:
http://www.hlebooks.com/ebook/eluger1.htm
Enjoy!