First:welcome to the forum, this is a great place,
you sure you have the right ammo? go get some surplus 7.62x54R ammo on the cheap, and see it will work. I have not heard 203g Bi metal SP for the 7.62 russian round. With a longtime disused M91-30, you have to use some force ( slam) the bolt forward to close and pull the bolt back with force and speed to eject the brass. Also clean the receiver wall and the barrel before go to the range. If use surplus ammo, make sure clean the bolt face and the bore right away, as the salt in the primers will rust your gun.