These were never 'captured'.
They are post-World War 2 conversions of rifles which the occupying German Army left behind in Norway when they were 'evicted' in 1945.
Prior to the War, Norway had been in a semi-union of military planning and procurement with Sweden and partly with Denmark. In a way it was a throwback to King Knut Svensson's northern empire, minus England. The whole thing fell apart when the Germans took Denmark in 5-1/2 hours (3-1/2 hours behind schedule) and Sweden permitted a powerful German force to travel through Swedish territory to attack Sweden's neighbour/partner/ally Norway.
By the end of War 2, Norway was a lot closer to the Western Allies and had found that of all the countries around, only England was willing to help, thus preserving the Peace sworn to King Harold Godwinsson following the battle at Stamford Bridge in 1066. British units were operating in Norway even in 1940.
WW2 American military production was truly massive and, following the end of fighting against Germany, the Cold War got into gear and was to become scarier and more dangerous until, finally, the blast-doors at the Shilo Bunker were closed for the only time: October, 1962. (Hard to believe it has been half a century since I had my butt planted in the Gunner's seat of a Firefly! Come to think of it, we are still waiting for those nice Chieftains we were promised.)
Norway came firmly into the Western Alliance following WW2 and thus was the recipient of huge amounts of American aid in addition to what Norwegian, British and German equipment it already had. In 1945, Norway had the world's ONLY squadron of jet bombers, German-built Arado 234 Bs. And suddenly they found themselves the recipients of shiploads of modern equipment, including bags and bags of shiny new .30-'06 ammunition.
So they did the logical thing..... and converted a bunch of German-abandoned Mausers to handle the stuff, complete with precision-made Norwegian barrels. The HA marking on the barrel of one of these rifles is Haerens Arsenalets: Army Arsenal.
And they can REALLY shoot!