WWI Imperial German Army Unit Markings

Hello,

I have an Erfurt 1912 Luger with the unit marking, "R.J.R.248.M.G.Z.30."
Attachment 96254

Can someone please decypher this marking and specify what each character/group of characters/numerals mean?

Thanks.

Infantry number 248th Machine Gun Regiment Z Section 30th weapon in the unit ;)

Another 1911 Luger, DWM, markings on front rear of handgrip:

Attachment 96463Attachment 96464

I was told by the seller that 13 R.J. 54 indicates that the owner (Hauptmann Heinemann Presumably) was attached to the 13 Royal Saxony Infantry Regiment Jägerbattalion No. 54.

The unit markings stamped through, possibly the owner transferred?

Was it common practice to stamp the handgrip with the owner/unit?

Thanks!