Hi, RobiNew! If undersatand correctly what you want, try the following. But note that m-dash has code 151 and n-dash has code 150.
Code:
Sub DASHES()
'Testo e Note: Sostituisce m-dash con n-dash
Dim mStory As range 'Nel testo e nelle note
Dim mRange As range
For Each mStory In ActiveDocument.StoryRanges
mStory.Find.Execute FindText:="([0-9])" & Chr(151) & "([0-9])", _
ReplaceWith:="\1" & Chr(150) & "\2", _
MatchWildcards:=True, _
Replace:=wdReplaceAll
Next mStory
End SUb