Bob,
There was a survey done recently on parts which break in use. Try this link:
broken parts survey
Lugers are a "finely crafted machine...built to be shot." They are not "fragile" in the ordinary sense. Remember, though, that they are 60-100 years old, and that many of them have had hard use--and you are shooting closer to the end of the use cycle, not the beginning.
It is a Luger's value which is the fragile thing here.
--Dwight