Lane Johnson wrote:
  10 years ago I bought a Harbor Freight wand type detector on salethat I use often on recycled wood.  It works well, but I suspect it wouldn't do particularly great for deeply buried nails in beams.  It does great for finding anything within an inch of the surface.   Saved me a number of times...
Thanks! I’ll go get one and give it a try. I wasn’t sure if I could count on those types of detectors, so I appreciate you sharing your experience.