You also don't need:
.Font.Size = 14
in the replacement expression.
Code:
Sub Tinkering()
Application.ScreenUpdating = False
With ActiveDocument.Range.Find
.ClearFormatting
.Replacement.ClearFormatting
.Font.Bold = True
.Font.Size = 14
.Format = True
.Forward = True
.Wrap = wdFindContinue
.Text = ""
.Replacement.Text = "[[^&]]"
.Execute Replace:=wdReplaceAll
End With
Application.ScreenUpdating = True
End Sub