I riveted on the aft deck tonight (9A). I used the squeezer for 90% of the rivets, which are 470 4-6. Everything went fine. When I stuck my head underneath to see how the rivets looked, I noticed that a number of them were cracked. I did nothing different. It makes me wonder about all of the rivets that I do blind and don't double check, aside from feeling that they are the right size. I assume that I need to drill out rivets where the shop head has a hairline crack in it, right? Is this common with 4- rivets? I can't say that I've ever seen it on 3- rivets. Do I need to visually check every single rivet that I buck or squeeze blind?