1. crown over erfurt
the manufactures emblem of the arsenal of prussian state that purchased two private factorys and started producing lugers around 1910.
the number 78 is supposed to be last two digits of serial that should be found on almost every part of gun along with inspector proofs on every piece as erfurt was very diligent with quality control.
2. the three marks on the right are a german military received proof. should be a crown over w ,p, and b with a crowned eagle last.
3. the 8.85 is the measure of the land of the barrel and designates it as 9mm.
the gun will never be a collector because of its state. It is a cool piece of history that you can have fun with and shoot at a good price. My two cents keep the grips and buy some bullets.