You could try to post a WTB in the Equipment Exchange.
My Ljungman and, it's original Mag parted ways. It took about 4 years to find one I could afford. If you keep your eyes open at shows etc. you will find one. Only one Mag was issued/rifle (loaded by stripper clips) so spares are not super easy to acquire but, are out there.
FYI Hakim Magazines will fit n' function in a Ljungman. Dunno if they're any easier to find.
Best of luck....I love my Ljungman