Thank you, that is another lead, but they look exactly like the one I listed above. The problem is that the magazine lock is too low and not the right size and the spring seem to be too weak. Also the gun jams occasionally when I use it. With the factory one in, I have no problems and can rapid fire 8 rounds.
I had to modify the non factory clip in order to even get it to work. After doing a lot of reading, the only thing I can come up with is that there are different specs for the different manufacturing of the gun.
I have a first manufacture of the Polish model that was taken during the occupation of Germany. It has the German army stamp on it, the stock grove, and the serial number suggest that it was an early model.
Here it the factory clip side:
Factory clip top:
This is one of the clips I purchase online on it side:
Non factory clip top: