I wondered too. You usually must work to get a primer to go off.
Even ramp rats, I thought previously, could not get that kind of force.
Aside- I knew a guy who made bullet clocks for competition awards. Typically a circle of .38 shells with undimpled primers and a clock movement from Micheal’s or the like on a nice stained wooden plaque. He took .38 shells, cleaned them up, and pressed in “inerted” primers. I asked him about his “inerting” process, and he said he put the primers in a 6” Griswold frying pan, put a “spatter screen” over it, and heated them on a gas stove until they popped! I never felt comfortable eating burgers over there unless they came off the grille...
Don’t bite down on the pepper-corns
It is easier to spray them with WD-40 and let them soak, if you want to make them inert.
Not really. Static electricity can ignite primers, as well as percussion and heat. Primers are not as clean as they appear. Minute amounts of the priming mix can end up on the primer exteriors during manufacture. In addition, tiny particles of priming mix 'dust' can fall from primers and accumulate in the bottom of a bulk container. Very slight movement can then ignite the primer mix and a chain reaction within the other primers can result.
Primers should never be removed from their original grid-oriented containers and stored in any other bulk container. Primer feed tubes on ammunition reloading equipment are the only exception.