Welcome Lorio702!
Your Luger sounds like a military issue (as evidenced by the grip strap marking) and should be 9mm...Some Lugers are 7.65 Luger caliber...If a standard #2 lead pencil [eraser end] will fit in the muzzle, it is 9mm...If it sticks going in (at the eraser metal band), it will be 7.65...(also called 30 Luger)...
Pics are a must; full side pics + any markings...Also marks on magazine...and magazine bottom...and top of chamber...Well, the top, anyway...
Holster??? Funny looking little cross-shaped metal tool???
Do the individual part numbers on your Luger match the serial??? Does the barrel serial match the frame serial??? How long is the barrel??? (You never know; might be a buried treasure)...
Did your father ever tell you the story about how he got it???
Please take advantage of the Search and FAQ functions here...There is a good YouTube video on taking it apart to clean it (and yes, it will need cleaning!)
