They are probably pretty scarce? Haven't seen a M219 for sale in any form, in years. Probably the original "combo gun" single shot, long before H&R/NEF or Rossi got the idea?
A kid I went to school with in the 60s had one. 30-30 and 12ga barrels, IIRC? One of my Tioga kin has one in 22 Hornet and I've been trying to steal it for over 25 years, with no success.