I'm assuming the chemicals in the lav tanks wouldn't have any negative effects on the bullets? Like ya know, set them off? And that the Captain knew this?
Hmmm... No impacts on the primers possible when flushed, cleaned, purged, or transported? No possibility the solid sludge remnants may be later incinerated?
As for the kid and the empty cartridges, he should have been taught to have more respect for them. He should know enough to AT LEAST ask mom or dad if he can take them to EACH specific place outside the house. Taking them to school, for example, could get him suspended or expelled...