Rookie Luger owner

[obs]

First time out..

My step-dad (air force) gave me a Luger 1918 a couple years ago, in a cigar box and wraped in an old t-shirt. I decided to find out more about it and came across this great site. I've done some research (tip of the iceburg) and began to collect ID info. All parts are stamped 38, including a mag. I did not find a 4-digit serial #...only the 38 and italicized o under the barrel. Could I have missed something??? I plan to post photos later...