Need help determining Luger manufacturer

[Potter]

Hi, I'm new the forum and hoping someone can help me out. I inherited a gun collection, most of it military stuff. There were 5 Lugers there- 3 DWM and two mismatched guns. The mismatched ones have no marks that I can use to determine manufacturer. There is nothing but serials on the outside of the pistols. There is nothing on the top of the barrels or toggles. One has a faint stamp on the bottom of the barrel at the base, but it has been re-finished and only a small fraction of the stamp remains. These have 4 digit serials with no letter suffix.
I stripped them down to the frames and found some numbers inside, but I'm not knowledgable enough to determine anything from them. One has G301 in a recess in the front top of the frame, the other has G348. Under the left grip each has a series of single letters on the side of the back strap. I'm hoping someone here can help me ID these. I'll link photos to one- I can take photos of the other but the frame appears identical.