I know my opinion isn't going to be real popular but my background and training support it as well as actual building clearance experience. I do not like a long gun for CQB in the civilian sense of clearing an occupied building like your home. I much prefer a handgun.
For interior team tactics I think a non rifle caliber carbine is a decent choice vs full rifle caliber and or full sized rifle. I do like a shotgun but also shorter length for say clearing a commercial building where contact can range out to 10 to 20 yards or more. Again, if close quarters are the rule, like a grocery store then I prefer the handgun to avoid grappling over the weapon if you end up in arms reach of the suspect. The long gun can also be a real hazard when securing the perp because 2 hands are required to properly cuff the subject. Slings are nice but they are also convenient to use by the bad guy to try to control the wearer and or weapon in a fight.
Few civilians have any idea of how to hold the weapon in a ready position and how to "pie" corners without presenting the muzzle to anyone just out of sight around the corner / obstruction.
I'm also not a real big fan of weapon mounted lights for searching, especially if there are potential friendlies in the area being searched. Again I was trained before weapon lights were conceived as a tool to be used. I do believe they have a purpose but not for initial searching due to muzzling what ever you are lighting up. Yes I understand the concept of using the "edge of the light" rather than direct beam but you are still pointing the loud end in the general direction of what you are lighting up. Under stress bad things can and all to often do happen. If you have never been there in a deadly force situation and the stress it provides, you just do not really understand the situation. The eye typically is drawn to the brightest portion of the beam of light and the difference in brightness can make friendly ID or target detection less than optimal. I like the idea of a hand held flashlight to scan then present the weapon mounted light for targeting. Having the handheld light on a lanyard so you can just drop it and go to 2 hand hold on the handgun when appropriate is a good option to me.
