[Mr V]

For the mandrels that are sticking up and you want to remove the rivet just use a punch to drive it through.

For drilling out 3/16" rivets use a 5/16" or larger drill bit and stop the second that the head of the rivet starts to spin, then use a punch to knock the remains out. That prevents the rivet heads from stacking up on the drill bit and from wallowing out the hole so that the rivet you put back in there doesn't grip correctly.

No matter how careful you are you cannot consistently drill right down the center of the existing hole so you create ovals, do it a couple of times and the rivet will not hold correctly anymore.

It does take skill to not drill into the material that the rivet is holding but it is easier to achieve that drilling down the center of the existing hole.

I agree that a pneumatic riveter is a great tool. I was one of the people who helped instal some of the 10,000+ rivets while building the field cases for the PNW division and w/o pneumatic riveters I don't know how we would have done it.