Parts for a Mauser es340b

[Jazbo]

  I have a 30's-40's Mauser model es340b.  I need the rear trigger guard screw
which secures the trigger guard to the stock and also secures the barell-receiver
group the the stock.  This screw actually screws into that Assembly.  Any info
on where and how to obtain this part would be   GREATLY appreciated.
 
                                 Thank,
                                  Jazbo