the Königlich Preußische Landgendamerie exists between 1812 and 1920. After that this Organisation was renamend in Landjägerei.
I think L.G. stands for the Landjägerei Gumbinnen district (L.G.)
Thank you for the response. I have been out of state and just now noticed your comment.
I believe the "L.G." marking to be that of the Land Gendarmerie because of the size of the lettering and the large Waffe Nr. "4630." This individual weapon number is far too high to reflect the number of these old carbines held by the Gumbinnen District in Prussia. Since carbines were only issued out in smaller numbers to Weimar Republic police agencies this number of weapons assigned to Gumbinnen is not logical. Also, these markings do not reflect the 1922 Prussian Police marking protocols which call for the "L" & "G" to be the same size of 4.2mm high while the following Centuria Roman numeral should be 3.1mm high. There is no Centuria number in this carbine marking as is called for in the 1922 marking regulations. Finally, the individual weapon number should be 2.1mm high.
The 1932 Prussian marking protocols are similar but are too late for this carbine to be proper.
I hope this helps you understand my logic in saying I believe the property markings to be earlier Landgendarmerie markings as this would coincide with both the age of the carbine and the existing marking protocols.