Very fucking unsafe to drive the muzzle of your rifle into any rigid object. Muzzle strikes are a thing. However you target the soft tissue of an assailant that has gotten within grabbing distance of your weapon and you do not want to kill them.

What this asshole did is dangerous on many fronts. They're using what appears to be their suppressor, which is atleast an 8" lever, that's likely screwed into an adapter that's then screwed onto the barrel. It's as much of a rube goldberg setup as it sounds. However under normal wear and tear still usually robust. It's designed to be used in tension to suppress the muzzle flash and report of a fired round by slowing and cooling the resulting gasses.

What it's not designed to be used as, is a FUCKING HAMMER, which puts it in compression. This asshole is striking a hard surface, with a steel blunt tube, comprised of a very complicated inner geometry. Not only that but he's striking at an angle levering the wide and rigid tube against a narrow coupler. I see a baffle strike and a ruined suppressor in his future. Possibly a ruined barrel crown depending on how much he just fucking bent that shit.

Now, to the biomechanics of what is happening. He had his hand on the pistol grip and his support hand on the foregrip. There's no fucking leverage there he can meaningfully exert. There's a reason spears don't have pistol grips. So the hand around the pistol grip is going to try to get the most purchase on the weapon. Which means it'll be riding up to the upper of the weapon and on the way there it could turn the weapon safety. Also, around that pistol grip is the trigger.

The driver of that car is being terrorized, by a moron, who very easily could've had a negligent discharge and shot her.

Fucking nightmare fuel all around. Those poor women. I hope they get justice because I would've gone to jail or died if it were me recording.

Some muzzle devices are explicitly designed to shatter glass alongside normal function - although they're commonly found on breaching shotguns.

Military and police training literally say that if you need to melee with your gun you use a muzzle strike - it's usually reserved for someone who's actively trying to grab your gun by the barrel and you don't actually feel like using lethal force. Using a muzzle strike against a fleshy target won't do anything to the gun's zero or ability to fire, you don't do it on a hard surface like glass. Hitting someone with your stock might actually break the gun if the recoil spring goes through it.