The trick to those expansion pin rivets is to simply push the center pin all the way thru with a small pin [ I use a finish nail that has been ground flat on the end]. That allows the rivet to release and be taken out of the hole ..Then you do as you suggest and put the pin back in from the front and tap it in so it can expand the rivet when it is back in the hole. Real easy..just have to watch not to lose the expansion pin.

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A Dalton