I am installing metal outside corners on new drywall. Framing is treated wood. How can I avoid the common 'cracks' from edges of the metal corners? I was going to use screws instead of ring nails, but the drywall screws caused the metal to flex out. Should I mud under the corners before putting them up? Any help would be appreciated.

Ok I seem to be having a problem. I cut out a piece of dry wall from the top floor room above the room where I am trying to run the wire. I have found the same wall downstairs and upstairs. My problem is trying to drill a hole to be able to pass the wire through. I can get through one board, then I hit another wood board, get through that and then I seem to hit another board. These are both interior walls so no insulation. Does anyone know how much of an extension I will need to be able to drop the wire through. I have tried a drill bit and extension that is about 26 inches, but still hitting wood. I would assume that once I get through the wood, that the wire will just drop down through the bottom wall. I would think that with both walls being hollow that there would not be that much room. This is a two floor drop. Thanks. Any question just ask in the vent you need more clarification.