You're asking what the LEO community is recently finding out, and it's counterintuitive. My best suggestion is to go to the box of truth website and look at their penetration tests for handguns, shotguns and rifles in drywall - it's very surprising. If you go with a frangible bullet, like a varmint bullet, you won't get the penetration you need which is why so many states don't allow 223 for deer hunting. On the BOT website, he showed how a heavier bullet will actually tumble and fragment after hitting the first layer of sheetrock (and I've confirmed this myself). What happens is as the bullet tumbles after the first layer of sheetrock it smacks the second layer sideways and/or fragmented. This does 2 things: 1) sheds velocity and mass very quickly and 2) greatly deflects the path of the bullet so that it is more likely to land in the structure of the home.