1st of thanks for looking and i am a VIRGIN to the luger.... got this gun at a gun auction today for $500.00

not sure if i did good or not i took a few photos and they did not turn out perfect, i will give all info on gun.........here we go
1 ..........the gun has been REBLUED
2...........grips have been replaced
PLEASE I NEED HELP.....
CORRECTION ON THE NUMBERS......160
the way i have luck is i wasted my $$$$
3...........the word GESICHERT, is where the safety is ?
date ontop of frame 1918
on top a CROWN over the word ERFURT & the #78 ?
some kind of marks
left side of gun
right side of gun
under the BBL is 160