I don't think these would be legal to hunt with the 3rd magazine as is.
"4 It is unlawful to hunt or trap with a set gun or with a pump, repeating or auto loading shotgun unless the magazine contains a plug that is incapable of holding more than 2 cartridges."
To me, that reads any shotgun whos magazine holds more than 2 (bolt closed or open doesn't matter) is verboten.