This is a basic, yet often overlooked shotgun technique. If you run out of ammo and are in a situation where you have no other weapon to transition to, or you cant waste the time to seek cover for a full reload, this is the technique you will need to use. Its a bit easier with an autoloader that locks back on the last round, I have a tendency to loose count of my rounds under stress and fully cycle a pump action closed. Its not a deal breaker, it just requires another step to open it back up again.
In “real life” though, most people dont walk around with those nifty shell carriers, so digging a round out of a pocket, pouch or weapon mounted carrier is going to be a bit slower than pictured here.