Rearrange columns - loop perhaps?

The following macro takes information from one sheet and puts it on another (basically swaps the order of the columns):

Sub SSETransfer()

    Dim rFirstBlank As Range
    Dim iRowCount As Integer
    Dim sCol As String

    Set rFirstBlank = Sheet1.Cells.SpecialCells(xlCellTypeLastCell)
    iRowCount = Sheet2.Range("A65536").End(xlUp).Row - 1
    
    sCol = "A"
    Sheet1.Range(sCol & rFirstBlank.Row + 1, sCol & rFirstBlank.Row + iRowCount) _
        = Sheet2.Range("A2", Range("A65536").End(xlUp).Offset(1, 0)).Value
    
    sCol = "B"
    Sheet1.Range(sCol & rFirstBlank.Row + 1, sCol & rFirstBlank.Row + iRowCount) _
        = Sheet2.Range("D2", Range("D65536").End(xlUp).Offset(1, 0)).Value
    
    sCol = "C"
    Sheet1.Range(sCol & rFirstBlank.Row + 1, sCol & rFirstBlank.Row + iRowCount) _
        = Sheet2.Range("R2", Range("R65536").End(xlUp).Offset(1, 0)).Value
    
    sCol = "D"
    Sheet1.Range(sCol & rFirstBlank.Row + 1, sCol & rFirstBlank.Row + iRowCount) _
        = Sheet2.Range("N2", Range("N65536").End(xlUp).Offset(1, 0)).Value

End Sub

It works perfectly, but only if Sheet2 is active - why is this?

Secondly, I am doing the same operation for around 20 columns - could I turn this into a loop?

Thanks for reading.