Comment: Hard to say,

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In reply to comment: Yes 1100, you're correct. (see in situ)

Hard to say,

but it appears to be a shotgun round being ejected. Bigger than a .223 round. Why does only one round cycle out? This tells me that a detach mag was already removed.

I can definitely see a pistol grip, like on an 11-87. Hard to make out any mag tube. Certainly, a mag tube would continue to feed additional rounds.

I think it may be a "Saiga" type shotgun or rifle. Not a bolt action motion being performed by the cop. Certainly not an AR charging handle.

These questions could easily be resolved in a video production studio. Don't hold your breath.