[Mr Twisty]

I'm not LE or military, but I do shoot quite a bit.

There was discussion in the Firearms section regarding .223 penetration, it will likely go thru numerous interior partitions till it hits something more solid than drywall. That makes it pretty dangerous in a house entry.

#7 buckshot is a good choice, but, like you point out, that's a lot of gun coming around a corner before you acquire a target. AR15 SBR would be better, but you're back to too much penetration.

My go-to gun is the 1911, I've also been playing with a long barrel 10mm EAA, love the 14 rd capacity and nasty accurate well beyond 100 yds. 10mm probably gets back into too much penetration in a house, so, damned if you do, damned if you don't.