In a story where the character has to take cover from bullets in a house, I actually read that a refrigerator (maybe steel) or cast iron tub could do a decent job of stopping ammunition. That or a safe. What do you think?
It depends on the bullet.
All bullets are not created equal. Handgun rounds (generally) pack a lot less punch than rifle rounds. Assault rifles have limits, but it’s still going to tear the place up. A high-power rifle will cut through most of the things you’d find in a house. An anti-material rifle will obliterate anything short of reinforced concrete.
I’ve never tested it, but a modern fridge probably won’t stop a bullet. The actual metal shell on the outside is quite thin. It’s more for show than actual structure. Metal is a terrible insulator and it’s heavy to move around. So, you put a thin shell over an insulated plastic frame, and you’ve got something that’s light weight, energy efficient, and looks expensive. Also, the metal shell is more resistant to casual abuse than the plastic beneath.
Heavy, metal tubs are becoming a rarity. They still exist, obviously, and depending on the tub, they may be heavy enough to stop some rounds. Ironically, the problems are the same as with fridges. The metal is a poor insulator, and the tub is extremely heavy. Even older metal tubs tended to minimize the amount of material used to keep the weight down. Fiberglass is the material of choice these days.
In either case, bullets will, probably, punch through, tearing ragged holes in the metal. And blowing apart the contents. If the bullet does stop, it’s still going to make a significant dent. You can look up what gunshot damage looks like, and it’s entirely reasonable your characters would try to take cover behind those objects, believing that they would offer safety.
The safe will do what you want it to do. It will provide shield against incoming gunfire. However, this is where things go a little off the rails. Free standing safes are a rarity. They’re fantastic for cartoons because it’s an instant cue telling the audience, “here’s a safe.” The problem with this is, if a thief wants what’s in the safe, they’ll just take the safe, and crack it at their leisure. The easy solution to this problem is to build the safe into the structure. The safe may be built into the concrete slab the house is built on. It could be part of the wall. It could be part of a larger furnishing piece that can’t be easily moved (such as a full office desk.)
The worst part is, a lot of these items will deflect the bullet. The metal shell on a modern fridge won’t stop a bullet, but it can cause it to bounce off in a new direction.
If you’re dealing with rounds that will fragment on impact, ricocheting can turn bullet from a single projectile into a spray of shrapnel. It is entirely possible to be injured from bullet fragments bouncing off concrete or hard metal surfaces.
Your characters aren’t going to have a lot of options for cover in a normal house. However, assuming someone is on the outside shooting in, they will have a lot of concealment. The best option is to hit the floor, make themselves as small a target as possible and try to avoid detection until the attackers leave, or they can find a safe way to escape undetected. It’s not, “safe,” but your scene doesn’t benefit from your characters safety. You may be interested in getting them out alive, but that doesn’t mean you should let your audience relax until you’re ready.
If your attacker is inside the house, then your character’s goals are to eliminate them before they’re found (and killed), or to escape (again, undetected.) If it turns into a gunfight, neither side has any cover. It is harder to accurately target someone through a wall, but you can make an educated guess for where they “should” be, and fire blind.
Incidentally, this is also the only safety your characters have. If someone is firing into into the house, it’s impossible to tell the difference between a kill, and someone dropping to avoid gunfire. Even if they did score a hit, walking in to confirm the kill is an extremely risky decision. They’re putting themselves in a situation where they could be easily ambushed and killed by people who know the layout of the place.
A house is not a good place for a firefight. You won’t be able to find safety when the bullets start flying. However, that is true for everyone. When you put your characters in jeopardy, you’re putting them in jeopardy, you don’t need to immediately walk it back and say, “but I’m sure they’ll be fine.” Tension works best when your audience isn’t sure what will happen next. Will they live? Will they die? Keep reading to find out.