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Shotguns are horrible for room to room. Here's why...
You need two hands.
Shotguns are a lot easier to wrestle away from you than any handgun.
Try this...
Turn off the lights. Put a broomstick in your hands. Walk downstairs (or room to room) with it ready to 'shoot'. Have someone bigger and stronger than you waiting somewhere in the house try to take the broomstick away.
Do this and you will change your mind.
Finally someone with some sense.
Clearing the house is a job for professionals.