Kids and I got the vertical ready to rivet on Monday and Tuesday we started popping rivets. It went pretty smooth at first, then I had to stop for some pneumatic rivet puller maintenance. Once we got past that, smooth sailing again. About half way through, the rivets started getting harder to install by hand. Is it normal to have the rivets difficult to place in hole prior to riveting? Seems like the closer we got to the end, the more frequent we found a tight hole. We did manage to make it through.