Well, since the Swedes were lucky and never got involved in WW2, I suppose most of the older model helmets ended up just sitting in storage after being repainted and receiving decals. After the war they had been superceded by the M37 and ended up unissued on the collectors market. Even the foreign troops trained in Sweden during the war received newer helmet types. The Norweigan "Polititroppene" got M26 helmets and the Danish "Den Danske Brigade" received M37s.