[AdamHeard]

We're pretty wild on hole size, as it varies with manufacture method. I try to keep the holes small in our gussets, as often we have at least a .196" hole in the tube it's mating with. We generally square up our frames with clamps or squares before riveting. Also, pieces like bellypans do a great job of squaring assemblies even with large holes in them. Larger gussets that cover more area and parts will get better alignment for the same size hole.

We use a pneumatic riveter whenever we can, it makes it easier for the operator to pop a bunch of rivets without getting tired and using poor technique.

As for drilling out rivets, we have a few designated bits we use for it. Drill bits are dirt cheap, don't be afraid to mess them up. That being said, I'm not sure how the heads damage the bit any more appreciably than just drilling (especially if that bit is never drilled into deep material where the upper flutes do anything).