This is a Norwegian 7,62x51 case, made at Raufoss. The markings indicate lot 30 of 1971, Raufoss.
A lot is a production run.
The casing belongs to either an NM60 full metal jacket (“ball”) round, or an NM62 tracer round. I don’t remember which type of ammo this lot was for, I might have a round somewhere from the same lot.
The NM60 and NM62 ammunition was mainly used in the AG-3 battle rifle and MG-3 machine gun. There were also some other firearms such as the MSG-90 marksman rifle, NM149 sniper rifle, and FN MAG machine gun firing the same rounds, but absolutely most likely, it was fired by an AG-3.
The Army and Home Guard used the AG-3 until very recently, some Home Guard (HV/Heimevernet) units still use it. The MG-3 and FN MAG are also still used, while the MSG-90 and NM149 were replaced by the HK417 rifle.
Hope this is helpful.
As a side note - a lot of NM60 has been sold as surplus on the civilian market and used as cheap training ammo, and hunting ammo for certain types of game. So there is the chance this was fired in a civilian hunting gun as well.