Using a pistol with a pistol brace against the shoulder, like you would a standard rifle; the weapon is now defined by ATF as a short barreled rifle. Don't argue with me, call the ATF. Cheek technique may be an interesting way around that issue.
Clearing a room or a house with a firearm needs specific training to be done without unreasonable risk. Pretty sure that this may be of use to some dedicated professionals on security details, not for the average armed citizen.
Not trying to offend anyone, but it is not useful to me.
JW