ID question: erfurt or DWM?

[opie]

hello all, new to the forum. I have been reading past posts and am just amazed by the knowledge here.

Here is what I have:

I just purchased an Erfurt Luger 9mm with chamber date of 1918. It is a mismatched gun. The entire upper is one serial number all matching(866), and the lower and side plate is all matching, serial number 7068 with a script d, so 7068d. (see pic which I hope attatched sucsessfully).

Here is my question:

It has been suggested by someone, who thinks they know things, that it possible that this is a DWM .30 cal lower? I have not seen anything on the site regarding the interchangeability(is that a word?) between the 9 and .30 cal?

I trust you all more than 'him'. Is it possible that this is a
DWM .30 lower 1/2?

I thought I saw a serial number chart here somewhere but can't seem to find it.

I only have this one pic as I am at work but was planning on a better first post than this.