ask why its so awful and why he wants it gone so much he'll pay you for it

"What is the downside of this HSA weapon"

"The HSA uses, WHAM. Which means Wickedly Hot Ammunition Munition. I know the name in the long version is hilarious, but the first people who laughed at the title weren't laughing after it's first tests. The WHAM round could generate so much heat in a single shot that all surrounding parties who were not wearing protective clothing burst into flames. It also generates a lot of smoke, and smells bad. I don't have the ammo for this thing because well, who in their right mind would carry it around in the magazine."

"...I'll take it."
You knew you probably couldn't have a use for it without the ammunition, but you might come around some later on.
It's time to step back out on the streets. You thank the man for the items and walk back out the door.
What now?