They said the woman hailing from Moradabad in Uttar Pradesh, was found carrying the rounds yesterday evening by CISF personnel at the Adarsh Nagar station when her bag was being scanned.
The lady was travelling with her father and other family members, they said adding her father produced a copy of his arms license and said the 20 rounds of ammunition (.32 calibre) belongs to him.
The woman and others have been handed over to the Delhi Police by the Central Industrial Security Force (CISF) team for further investigation, they said.