Not gonna work.

There is a reason a group of cops will have 2 with real guns and one going "non-lethal." It simply doesn't always work. A determined attacker or one who is plain nuts or high on drugs may not get the message and you'll just piss him (or them) off more.

Look into something like #4 buck or a high velocity 5.56 round that won't penetrate barriers so well. The honest truth is that anything that's gonna penetrate a bad guy is gonna penetrate drywall.

Keep in mind that scumbags like to travel in packs and pairs.