I know drywall is useless for stopping bullets.
But was wondering about 2 specific common elements in houses and apartments that should provide at least some actual ability to stop bullets.
One was the length of a wall (ie the studs in the interior wall) like if using edge of interior wall to cover a window or door how many studs does it take to make a difference vs 9mm/40? Or vs Shotgun or rifle? I've never worked construction, and haven't done house wiring since high school so don't recall for certain the typical stud spacing for interior walls.
Other was Hot water heater, hadn't considered them as good cover because I've only seen empty ones shot in farm junk piles. But Water heater in a home is going to be filled with water, which is very good at stopping bullets. And with essentially endless water being supplied, it would actually take several holes before leakage overwhelmed flow rate filling the water heater.
Also had epiphany the other day when thinking about improving dryfire setup, realized not only would a 12x20" AR500 target https://www.amazon.com/dp/B082WRGK2N...ing=UTF8&psc=1 make a very safe target/backstop for dryfire, it would also be superb cover in a home invasion.