They didn't. the issue is based on an agents interpretation (more than 1x) of something they don't know about. Search the "engraved" or etched sear debacle. Some agents have now interpreted an image on the receiver where the sear pin would be, as a machine gun.
http://www.saysuncle.com/2017/01/24/...r-machine-gun/
HPA can't come fast enough.