Bom se seu intervalo estiver com dados isso deve funcionar:

Sub Teste()
    Dim rng As Range, c As Range
    Dim uC As Long
    Dim sh As Worksheet

    Set sh = ActiveSheet

    With sh
        uC = .Cells(12, .Columns.Count).End(xlToRight).Column

        Set rng = .Range(.Cells(12, "G"), .Cells(12, uC))

        For Each c In rng
            c = UCase(c.Value)
        Next

    End With

End Sub

O que significa esse G ?

Ah ta, esquece, pois é coluna 7