Old gunpowder from 1957! Stuff that old is risky. I am going to tell you, the reason that old surplus ammunition is on the market is that the originating agency, typical a military organization, decided the stuff was too dangerous to issue and too unstable to keep in storage.
They have tests, the more sophisticated use gas chronographs to determine the amount of stabilizer left in the powder. Or they use reports of accidents from their ammunition technicians to decide to discard old lots. We no longer live in a world where the US Army knowingly issued defective 1903 rifles, (sell price at the time, $40.00) and kept them in service till the barrel wore out, or the receiver blew up in the face of the user. Now days, the Army has to budget for the cost of short and long term rehabilitative care for its injured personnel. And medical discharges are god awful expensive in the long run. (Which is why the Army does all it can to deny service related injuries, just talk to Veterans about their Gulf War syndrome claims)
Old gunpowder deteriorates, and as it deteriorates, one of the problems it creates is pressure spikes. The stuff no longer burns nice and evenly, instead the pressure curve gets to be highly irregular with the interactions between pressure waves off irregular powder granules. It is called burn rate instability. I have lots of posts accounts of individuals who blew their guns with old ammunition. And they don't know why.
By the way, the ammunition manufacturer's don't warranty their ammunition past ten years.
If the bullets can be pulled, and there is no corrosion in the case, then new powder can be put in the case and the old bullet stuffed on top. Unfortunately it sounds as though your primers have duded out. Don't know why, unless NOx outgassing from the gun powder has dudded them. Primers last a very long time.
As you can see in this thread, many in the shooting community believe ammunition is pristine and immortal. Which is why discussions about ammunition having a shelf life, and gunpowder getting dangerous, tend to be shouted down.