Not knowing what kind of ammo you bought or its condition, I can only give some basic suggestions. Check the primers and note the indentation. If it is erratic, you probably have something in the bolt body that is jamming up the works. If the primer indents are consistent and light, there is probably old congealed grease and other stuff, like rust, or even tow. If the primer indents are deep and consistent, then it probably is the ammo. I would strip the bollt and soak it overnight in a good cleaner, then scrub the interior. A broken spring or firing pin will be immediately evident. It is possible, too, that the spring has taken a set. Try stretching it and see if that helps. If it does, it is time to order another spring. Look at the tip of the firing pin and see if it is uneven. peened, or short. Replace it if it is bunged up.
Look at the ammo. If it is in original containers, do they show water damage or damage from rough handling? Are the cases or bullets corroded? Break down and buy a box of modern sporting ammo and see if it fires consistently. By this time, you should know if you have a keeper or the raw materials for a rifle floor lamp. Good luck.
