Finnish marked DWM Luger.
It is serial number 44xx (you can see the entire serial in the pic).
It does not have an alphabet letter. Instead, it has a proof where the alphabet letter would go.
It is kind of hard to make out the proof and I took about 10 pictures trying to get it. The best two pics are below:
Looking through a proof book it appears it may be a factory rework code, but the proof guide shows letters (such as RC or U with the two dots over it) with the proof - mine doesn't have that.
My other Finnish lugers are all alphebet ones - why isn't this one? I think it is still commercial production because it has the crown/Nitro proof on the left which should denote commercial.