Good lord lol if the primer when struck on a centerfire cartridge doesnt detinate imediatly or i a few seconds it never will. The thought that a jar or bump would set it of a day or years later no never ever its not nitro glycerin. Its gun powder not unsafe and leagle to buy unlike glycerine or such. If shels were that unstable or could be they wouldnt be available to the public. Black powder in the 1800 was that unstable. The newer powders we use today are made of the same elements but are reformulated to be stable so's that our mishandling is safe you have no worries of collecting DUD AMMO. Just because the primer is struck doesn't make it unstable. The fack that it had been struck and didn't go off is a sighn that its verry stable. ALSO PLS REMEMBER IN THE FIRST OF MY REPLY I SAID CENTERFIRE NOT RIMFIRE. RIMFIRE IS ALL TOGETHER DIFERENT. rimfire the priming compound is located in the rim of the shell. Sometimes the compound is not evenly placed all the way around the rim of the shell. That is why u may have a miss fire in rimfire pull the cartridge twist it so the firing pin will strike a different location and it fire the second attempt. So in theary you could acualy throw rimfires hard at a hard serfice and detinate one easily. When i was a kid we used to stick 22 shells in the muddy bank and shhot at them wit a bb gun. When you hit one it went bang in the mud. Centerfire is a cartridge eith a replacable primer that has to be struck inthe center. Rimfire has to be struck from the outer edge to be detinated,like 22,17, and theres a hole mother load of them from histery that i dont know the calibers but were learning. Also centerfire cartriges that have been struck and have not been detinated can also be a week strike from a week firing pin,or hammer spring on the gun it was fired from.