Primers - decades ago I periodically visited, as part of my job duties - "The Denver Ordnance Plant in Lakewood produced ammunition during World War II. The plant was the largest federal project in Colorado history before its conversion into the Federal Center, which today houses dozens of government agencies."
Upon walking thru the huge building, I noticed that there were no long continuous hallways between individual spaces. Somebody patiently explaned to me that this was designed to contain blast energy in the event of an explosion. The explosive used in primers is lead styphnate and other chemicals - enough energy to make for a big blast if enough of this stuff exploded.
I was then told that a plant employee was cleaning up a bunch of culled primers and placed them in a bucket. One of the tiny primers exploded for some unknown reason, possibly static electricity or concussion. This caused a massive chain reaction resulting in death.
I keep my primers separated from gun powder. I have no plans for making primers. A 10K primer limit is usually mandated by various governments, like RCW 70.74.350. I will never use a tube fed priming tool. Squeeze type priming tools have a barrier between the primer being seated and the primer container to prevent a chain reaction. Hopefully, OSHA will not make primer manufacturing in the US economically impossible. My shooting expectations would be negated if all I had was a flintlock rifle.