Diagram of pins in order of removal.
Why only remove pins from right side, and replace them on the right side?
One, if you drive pins out in both directions, you increase the size of the frame holes on both sides. If the left side never has pins pushed clear through, that side stays tighter,allowing the pins to stay tighter in the gun.
Two, the Trigger Pin has two cuts in it, so it can go in in either direction, to allow the Slide Stop Lever to fall into this cut. This cut holds this pin in place. If you remove this pin from the left side, you get the Slide Stop Lever from one cut, only to have it fall into the second cut, and you have to do the SSL wiggle all over again.