My ten year old son gave me a similar problem.
There's me in uniform sending him off on a flight to see mum (usual pilot family), when there is a big kerfuffle in security, and I get an urgent PA to see them IMMEDIATELY.
Turns out he had taken two clips of .303 bullets in his bag, to show his mates. Red faces all round, as I try to explain. But what annoyed me is that the brain-dead security team and manager did not know the difference between live rounds and disabled dummy rounds - they had no firing caps.
But security would not accept the bullets, so I then had two clips of bullets in MY bag. Since the offices were empty I stashed them in the crew room, until I returned, and hoped nobody else would find them. Enough trouble for one day.
Thanks, son....