I need to drill a 5/8" or 3/4" hole in a fireblock in an interior 2x4 finished wall in order to run a cable. I have reasonably good access from above the wall in the attic. I could have access from below the fireblock but I don't want to cut the holein the sheetrock for the box until I'm sure I can get the cable run. I am considering either long flexible bits (like Greenlee D'Versibit auger bits) or using 18" extensions for auger bits to reach the fireblock. I am concerned about flexible bits being able to punch completely through the fireblock. The fireblock is centered about 42" from the ceiling or 48" from the floor. I'm interested in any experience by others on the group who may have done this task before and their suggestions on the best way to approach this.
Also, the fireblock seems to be at least 3" thick as measured by the stud sensor. Is it common for fireblock to be a doubled 2x4?
John Keith snipped-for-privacy@juno.com