Help needed to identify luger pistol

Rodrigo, Since it appears from your first photo that the top of the Crown is missing, I suspect that your long 7.65mm receiver has been cut back to accomodate the short thread 9mm barrel. If this had been supplied as a 9mm by DWM, I would have expected the crest to be complete on a short threaded receiver and frame, as all the rest of the M1906/9mm pistols. Also in your photo #2, you can see that the FRONT of the barrel flange lines up with the end of the frame, rather than the REAR of the flange. This indicates to me a non-DWM rebarrel job. This may have been done by a Portugese arsenal; if so, the barrel will probably show some Portugese proofs such as a nine in a circle, KK over a number,ect. I would guess that the serial number of your pistol, falls in the accept range of the Royal Port.Navy 7.56mm pistols: 1 to about 5000. Where as the original RMP pistols in 9mm were only numbered from 1 to about 1000. This appears to me to be a cleaver fraud, but difficult to be sure from just a photo. Tom h