I finally fired it all but for years I used some 7.65 Argentine Mauser ammo dated 1933 and 1934. It was made by FN in Belgium. It would very rarely hang fire but only for an instant. Not really dangerous in a bolt action as long as you are willing to keep the rifle pointed downrange until it fires or until you are certain it will not.
Very old ammo would be a possible danger in automatic weapons due to hang fires but it really has to be old or stored in bad conditions to be dangerous.
I had some Ecuadorian Army Mauser ammo that was about 1/2 duds.
It’s not a good feeling cycling those rounds out after the primer has been hit with a firing pin.