I've been thinking about picking up a Luger.  I realize a nice one with matching numbers is probably out of my price range, but I'd be satisfied with just about any example of the type that I can admire and shoot from time to time.  Nickel-plated ones come up occasionally for reasonable prices and any collector value is shot so I don't have to feel guilty about putting a historical artifact at risk by firing it.  My question is twofold: do the nickel-plated guns have any function issues unique to them, and are there any particular things to watch out for aside from the matching numbers?

Most of the time there are no issues due to the plating. Mismatched non fitted parts however are another thing.