Thanks for all bits of info guys. I'd love to find some kind of evidence of norwegian use of these helmets. Since the navy also had ships and guns supplied by the US, it's not unlikely they also had some of these helmets. I've seen several british helmets with battleship grey paint. I suspect these have seen navy use. The liner of my private purchase helmet has two spots of grey paint, on the upper side, facing the rim. I think it has been in a similar helmet that were painted grey? I'll try to take some detailed pics.
Here's some more period pics I found of the ww2 norwegian navy. From ships like KNM Stord, HnorMS Glaisdale, KNM King Håkon etc...Attachment 414559Attachment 414560Attachment 414561Attachment 414562Attachment 414563Attachment 414564Attachment 414565Attachment 414566Attachment 414567Attachment 414568Attachment 414569