Hey Paul,
Try
http://www.hlebooks.com/ebook/eluger1.htm
This e-book costs $7.95, which--per dollar--just may be the best Luger investment you could make at this point. Though barely more than a dozen pages, it will give you a basic understanding of the Luger System's mechanical function, including the issue of ammunition.
And if you have any further questions, the sages here at the forum will assist you, as you may see.
I am pretty new, and it helped me a lot to prepare for my first Luger.