I went through a 1000 year flood in 2015 that flooded into the second story of my house. A cleanup crew came In 2 weeks later and began throwing all off my flooded belongings into a deep burn pit way off at the corner of the property. Many loose primers and hundreds of rounds of ammo went into that pit. They had been covered with water for over 2 weeks. That has been 8 years Now. I still have primers going off in that pit when I do debris burns. We don't light it and stand around. We light it and get the h--l away. Primers in the ammo will also detonate. Even with the powder having had enough seepage into it to render it bad So it won't burn. Not so with the primers. Primers are very resilient.