The most that will happen is under ignition, or failure to fire, and delayed firing.
I had some old primers made back in the 30s that gave delayed firing of a few seconds. That is the most dangerous.
Load some up with a min load and see
They don't get stronger with age and turn into primer godzilla's!
Failure is part of success!
This year will go down in history. For the first time, a civilized nation has full gun registration. Our streets will be safer, our police more efficient, and the world will follow our lead into the future!" -Adolf Hitler,1935"