Function myTime(myRng As Range) As String
Dim Addr As String, sTime As String, eTime As String
Dim first As Long, last As Long, i As Long

Addr = myRng.Address
first = Range(Split(Addr, ":")(0)).Column
last = Range(Split(Addr, ":")(1)).Column

If Application.CountA(myRng) = 0 Then
    myTime = ""
    Exit Function
End If

For i = first To last
    Select Case UCase(Cells(myRng.Row, i))
        Case "X", "S", "R", "G", "C", "A", "M", "T", "B", "x", "s", "r", "g", "c", "a", "m", "t", "b"
            sTime = Format((i - 3) / 48, "hh:mm")
            Exit For
    End Select
Next
For i = last To first Step -1
    Select Case UCase(Cells(myRng.Row, i))
        Case "X", "S", "R", "G", "C", "A", "M", "T", "B", "x", "s", "r", "g", "c", "a", "m", "t", "b"
            eTime = Format((i - 2) / 48, "hh:mm")
            Exit For
    End Select
Next
myTime = sTime & " - " & eTime
End Function