Those are just metal "caps" that push into the screw heads..
The screws are located under those metal "pins" The metal pins are actually screws that have metal caps pushed into them so they look like you can't unscrew them. Take a very sharp small screw driver and pry under those caps and they will pop off revealing the screw head.
I had a similar lock in our home. Those are caps as another poster said. A putty knife or slim screwdriver should pop them off, revealing screws.
And yes, the protruding part is always inside. The external piece is almost always flush or near flush. But never with screws showing.
Grandpa was a fireman and locksmith. Had I not grown up in his shop, I would have been in the same boat wondering how to get them off.