Hi.

First, a small correction of the time for occupation og Norway, it startet April 9, 1940, ended May 8, 1945.
From what I know the serial for NC stamped receivers in 1944 were supposed to bee numbered with NC60, ended with NC1200, but in lowest known were 673, highest 1095.
Yours might be correct, but also an "copied" one , as the grinding of bolt and then stamping new number, I've never seen before. That is not that it could have been done, but it is uncommon, or never seen.