Around the circumference of the pin, centered(more or less) in the bolster.
When the knife is assembled the pins are peened over, mushroomed into a slightly chamfered hole in the bolster. Then ground flush and polished.
The grinding and polishing the pin and bolster together blends/somewhat smears the metal together and it makes an invisible seam where they meet.
Any time you adjust the pivot afterwards by squeezing the bolsters together, or even if you tried to loosen one and spread them, you change the distance from one side to the other.
But the pin can't shorten or lengthen with it.
This movement of the bolsters but not the pin will sperate them ever so slightly, and then you will see the line where they meet, usually about an 1/8" hair line circle on the bolster.
It only has to move a few thousandths of an inch for this to happen.
Go far enough and its a seem you can feel, where(with tightening the joint) the pin becomes a little proud of the bolster.
I'll see if I can find one of my knives with the pin visible and post a pic..