I'm drilling and tapping a hole into a stud wall for a M16 rod. I've hit a snag and i'd like some advice.
I need to bore multiple perfectly level 14mm holes to around 75mm-100mm deep. I've predrilled with a 8mm bit and then used a 14mm wood bit in hand drill. The main issue is that one stud has a bit of metal (possibly a nail) buried in it at around 50mm deep. This caused my drill to deviate and has ruined the hole. I've hacked the protruding piece of steel out of the way using a carbide burr, but it hasn't done the hole any favours. I have a solution to salvage it, but it involves drilling a larger hole.

I need some ideas on what sort of drill bit or cutting tool I can use that will get through the metal without deviating from its intended path. Some sort of long hole saw or annular cutter, but I can't see anything longer than 50mm.
I now have a drill fixture set up on the wall to allow me to drill straight and clean holes. Mounting something in this shouldn't be an issue.

I need to bore multiple perfectly level 14mm holes to around 75mm-100mm deep. I've predrilled with a 8mm bit and then used a 14mm wood bit in hand drill. The main issue is that one stud has a bit of metal (possibly a nail) buried in it at around 50mm deep. This caused my drill to deviate and has ruined the hole. I've hacked the protruding piece of steel out of the way using a carbide burr, but it hasn't done the hole any favours. I have a solution to salvage it, but it involves drilling a larger hole.

I need some ideas on what sort of drill bit or cutting tool I can use that will get through the metal without deviating from its intended path. Some sort of long hole saw or annular cutter, but I can't see anything longer than 50mm.
I now have a drill fixture set up on the wall to allow me to drill straight and clean holes. Mounting something in this shouldn't be an issue.
