Dragon's Breath Rounds
Dragons Breath rounds are shotgun shells that, rather than being filled with buckshot, are filled with magnesium shards which, upon hitting air, immediately set on fire.
This means that someone out there looked at a shotgun, a device capable of turning your face into raw meat, and decided that it needed the ability to shoot fire.
Dragon's breath rounds are understandably illegal as hell, and have seen virtually no use in combat. It's way more dangerous than it sounds.