It was related in the link that the shooter was an inexperienced reloader. He pulled the trigger, nothing happened, so apparently he loaded a fresh cartridge and fired it.
Apparently, there was no powder in the first cartridge, or not enough to drive the bullet from the barrel.
Inattentive reloading, failure to check each and every case before seating the bullet (a MUST) and ignorance of typical shooting problems brought this on.
How many shooters know to stop and keep the pointing downrange if nothing happens when you pull the trigger?
Yes, it could be a dud. That is, the primer never ignited.
Or, it could be only the primer firing, which often drives the bullet just far enough up the barrel to allow a second cartridge to be chambered.
Or, it could be a hangfire. Hangfires are comparatively rare but do happen. This is when the primer smolders, and goes off a moment later, igniting the primer.
Anytime, ANYTIME the gun doesn't sound normal, or you pull the trigger and nothing happens, keep it pointed downrange for a full minute. Then, open the action with your fingers and body out of the way, and discard the round.
Ensure the bore is clear. If you can't see daylight, or there's something blocking most of the light, clear the barrel with a cleaning rod and patch.
Such movements are second nature to older shooters like me, but many of the newer shooters have never heard of a dud, underload or hangfire.