Eric,
First get the book that was recently published about them. It's not expensive and has all the basics, including a serial number list. Written by the late Ed Sayre:
"The Luger Snail Drum and other Accessories for the Artillery Model Luger"
published by Mowbray Publishing and priced at $25.95 it's a steal!
http://www.gunandswordcollector.com/...yre_luger.html