When I worked as a sheet metal fabricator, making tail sections for C-130's and rear boom sections for Bell helicopters, among other aircraft subassemblies for a factory in Nashville, we spent a lot of time in training to install rivets properly. The rivet must be an almost perfect fit in the hole, and when it's expanded ("bucked") it not only clamps the pieces together, it also expands to fill the hole, creating a bond almost as strong as a solid piece of metal. The very best riveted joints are done with "hot" rivets, ones that are installed while cherry red and hammered into place with pneumatic rivet guns. Look at the construction of older buildings or bridges with riveted steel beams instead of welded ones for a good example of hot riveting. High rise buildings used to be assembled with rivets heated on a charcoal forge and thrown to the riveting crew who caught them in funnel-shaped metal cups and installed them with tongs and pneumatic hammers while they were still red hot.
Jerry
