I don't keep my AR at hand for HD stuff..... BUT, it's always empty chamber, 30 round mag loaded to capacity with 75gr TAP, just incase ;) I could have it ready to fire within 10-15 seconds.
I NEVER want to clear my house, let alone with a long gun. The shotgun, within 2 seconds, it's in my hands and ready to go, but exiting to bedroom with an 18.5" barrel long gun isn't going to be easy. My USP I can in my hands within seconds. Much easier to clear a house with. I have NO formal training clearing a building. I never want to do it, though, I'm familiar with the fatal funnel, making wide corners if you can, never round a corner Hollywood style, kind of keep the pistol tucked into your chest (think holding a slung AR). Is that the offical way? Maybe not but it seems like it'd be logical. Again, no formal training. I don't want to sound like an internet commando, haha. I always tell myself, the USP is for investigating an odd sound inside the house (won't go outside). The shotgun is for defending against a KNOWN threat. Truth is, I'll grab what I can or deem needed at the moment.
As far as self defense ammo in your AR, IMO, use the heaviest grain OTM rounds you can. I don't care if it's a 1:50 twist. HD, even with an AR will no be far enough for anything to keyhole and become unstable. If you're going to be shooting 200 yards (obviously not self defense ranges), yeah heavy grains may keyhole with an inappropriate barrel twist. Heck, at self defense ranges you'll have to aim 1.5" high anyway due to the sight height, unless you sight your AR at 7 yards ;)
Hornady TAP in 60gr or 75gr, and Federal TRU also has some nice options. The 64gr soft-point TRU seems to have very good ballistics. Even plain old 55gr FMJ round will do. You'd be close enough that the velocity will still be high enough to create a yaw effect. I'd still use the best you can. You're not limited to 55gr FMJ.
jonconsiglio - Nice pictures! Looks fun!