Source: Waterdeep - Dragon Heist

Wondrous item, uncommon

Smokepowder is a magical explosive chiefly used to propel a bullet out of the barrel of a firearm. It is stored in airtight wooden kegs or tiny, waterproof leather packets. A packet contains enough Smokepowder for five shots, and a keg holds enough Smokepowder for five hundred shots.

If Smokepowder is set on fire, dropped, or otherwise handled roughly, it explodes and deals fire damage to each creature or object within 20 feet of it: 1d6 for a packet, 9d6 for a keg. A successful DC 12 Dexterity saving throw halves the damage.

Casting Dispel Magic on Smokepowder renders it permanently inert.