Facebook Marketplace gun sales

Gunsellers are secretly posting assault rifles and other guns for sale on Facebook Marketplace by disguising them as posts for gun cases or empty boxes. The practice is in defiance of Facebook's ban on the sale of private guns and ammunition.

The practice was spotted by the Wall Street Journal, who discovered over-priced cases listed in several US states. When contacted, sellers revealed that the sale price included the firearm that belongs to the case. 

Facebook uses a combination of artificial intelligence and human moderators to police sales on Marketplace, calling into question the workings and effectiveness of its system.