Welcome to the forum! Sounds like you have a Luger similar to mine which is also a 1917 DWN serial # 9242 (pics here
http://forum.lugerforum.com/showthread.php?t=28102 )
I've had the same struggle with myself about whether to shoot mine or not. I've been told by a gunsmith and the gun expert who sold it to me that it is safe to shoot but still I'm not sure if I want to risk it!
Looking forward to seeing pics of yours!