Obtain a manual from the maker or find a gunsmith
Go to http://stevespages.com/page7b.htm and scroll down to the "L" section. You can find a Luger manual there.
Try Numrich Gunparts for a breakdown and parts list.
If you don't have the owner's manual, find a gunsmith and ask for help
Parts breakdown is in link below:
go to: gunbroker.com search 'luger'
try www.midwestgunworks.com I found the 101 manual here.
rcpw.com
You may be hard pressed to find the manual; cannot check right now as the Sears manual site is down for maintenance. but the parts site is active. The parts breakdown is there and you can copy and save the pictures to get the breakdown. There is a link to the engine parts breakdown ther as well. See link below
Follow instructions in owner's manual. If you don't have one, find a gunsmith.
You can find the manual here http://www.ebay.com/itm/151048774866
You can find original Luger magazines at gun stores, online firearm retailers, auction websites, and from private sellers. It's important to verify the authenticity of the magazine and ensure it is compatible with your specific Luger model.