‘Dead nuts’ is an idiom used by skilled workers or machinists to refer to something accurate—not just ‘good enough’ accurate but precise, dead center, right on the spot accurate. The word ‘dead’ here could be connected to ‘dead on,’ which means ‘exact’ or ‘exactly right.’

dead nuts adjective accurate; "dead on". His measurements were dead nuts on. See more words with the same meaning: accurate, probably, likely, certainly.

'Dead On' means accurate. 'Dead Nuts On' means whatever you want it to mean including the extraordinary possibility of the inadvertent insertion of "Nuts" between 'Dead' and 'On' in the well known expression 'Dead On'.