I do admit I did not really look at the marks on the action. It does appear to have both Belgian & German marks. The D=75/18.9 is definitely a Belgian mark as is the crown over ELG, the Perron, the PV mark & the 16/C in diamond can be either Belgian or German prior to 1924. The D=75/18.9 is as stated, a 75mm long chamber having a rear diameter of 18.9mm. This mark was used only on Smokeless Powder proofed guns "In Belgium" from 1892 to 1924. I have never seen that mark from a German proof house. The Crown/W is a German mark as you say.

Miller/TN
I Didn't Say Everything I Said, Yogi Berra