9mm carbine vs shotgun in an apartment — what's actually the tradeoff?

Question

My situation's probably common — we're in a mid-size apartment, three kids down the hall, wife is cautious about recoil and noise. I'm wondering if a 9mm carbine makes more sense than a shotgun for home defense in close quarters.

I know shotguns are the classic choice, but I've heard the argument that a carbine is easier to aim, lighter to handle, and doesn't over-penetrate as badly. On the flip side, shotguns are proven and simple.

My specific concerns:
- Recoil. Can my wife actually shoot the gun if she needs to?
- Penetration through apartment walls into neighbors' units.
- What the gun actually does if I'm in the dark and stressed.
- Storage that keeps it accessible to us but away from the kids.

I'm not looking for competition opinions — this is purely about keeping my family safer. If anyone's dealt with this choice in an apartment setting, I'd like to know what you landed on and why.

Ben Rourke · Accepted Answer

I'm going to build on what both of them said and add the piece that usually gets left out: what happens to your hearing and your ability to communicate after you've fired.

keep.simple's right about penetration. gulfcoast_ops is right about the sound signature—both rounds are punishing indoors. But here's the thing that tips the scale for me in your situation: **a 9mm carbine lets you shoot more rounds faster with better control, and you need fewer of them to stop a threat.**

A shotgun's strength in an apartment isn't that it's "simpler." It's that each round carries more energy. The weakness is recoil management and follow-up accuracy, especially for someone new to recoil. You fire once, the gun climbs, you need time to reset your sight picture. With a 9mm PCC, the recoil impulse is softer and faster—your wife can stay on target through two, three rounds if needed. That matters more than the myth of the spread doing the work for you.

Capacity is the quiet argument for the carbine. A shotgun holds 5–8 rounds. A 9mm PCC holds 17–30. In a home defense scenario where you might be shooting in low light and under stress, having rounds on tap without reloading changes the math. You don't *need* 30 rounds, but you also don't want to be empty after two shots if your first two don't stop the problem.

My recommendation: **go with the 9mm carbine.** Run quality ammo (HST or Speer), get a red dot, train your wife on it first—not your shotgun. She'll shoot it better, faster, with less flinch. You get penetration control gulfcoast mentioned, and your kids hear less blast.

You'll still wear earpro to the range; you won't have it at 2 a.m. Both rounds are loud. The carbine's just more controllable when they're not.

What's your timeline for getting both of you on it?

Katie Epps · Answer

The penetration concern is real, but the gap between 9mm carbine and shotgun is narrower than you'd think—and goes the direction most people get backwards.

Modern defensive 9mm (Federal HST, Speer Gold Dot) expands and sheds velocity fast. Through drywall, it penetrates roughly 12–15 inches before fragmentation. Buckshot? Federal 00 goes 18–24 inches depending on the load. Slugs worse. The carbine actually wins here if you're running quality ammo.

Shotguns have one real advantage in apartments: you don't need precision under stress. But that cuts both ways. In the dark, tired, and scared, buckshot hits a wider area—true. It also means less control if a kid somehow moves into the hallway. A 9mm PCC with a red dot gives you that accountability back.

Recoil-wise, a 9mm carbine is a different animal than a handgun. Your wife can train on it without flinching. A 20-gauge shotgun is also manageable for most people, but requires actual practice to shoot well; people *assume* shotguns don't need training because "spray and pray" is a myth.

The honest answer: either works. The 9mm carbine asks less of untrained hands under duress. But get specific ammo data for whatever you choose, and store it separate from mags if you have young kids—mechanical safety isn't enough when they're in the house.

What's your wall construction like? That actually matters more than the caliber question.

Renata Silva · Answer

kept.simple nailed the penetration data. I'm going to add what doesn't usually make it into that conversation: sound signature and blast pressure in a confined space.

**What happens to *you* when the gun goes off indoors?**

A 9mm carbine is roughly 155–160 dB at the shooter's ear. A shotgun with 00 buck runs 155–165 dB. Both are loud enough to cause temporary threshold shift—that ringing in your ears where you can't hear your kid crying or your wife yelling. It's a real factor in a dark apartment at 2 a.m. You're already stressed; now you can't hear anything for 10 seconds.

Neither one is getting suppressed legally in most places, and subsonic 9mm loses the expansion benefit you want for defense anyway.

**What's the training gap here?**

This is where the internet argument mostly breaks down. A shotgun *looks* simpler because the spread sounds idiot-proof. It isn't. You still need to practice recoil management, sight picture, and follow-up accuracy. A 9mm PCC with a red dot is actually *easier* to shoot accurately under stress because the feedback loop is tighter—you see the hit, you can correct. Shotgun? You're guessing what the spread did.

Your wife needs to train on whatever you pick. Not range time—dry fire practice, low-light, movement. That matters more than caliber.

**My recommendation for your actual situation:** 9mm carbine, quality hollow points (HST or G9), red dot, stored with the bolt removed in a quick-access safe. It gives your wife a gun she can control, less neighbor liability, and you get accountability in the dark. Get both of you on it for 2–3 hours before you consider it ready.

Your wall construction would help me refine this. What's between your unit and neighbors?

Greg Deluca · Answer

Hold on—before we keep going down the 9mm carbine path, I need to know what's actually between your unit and your neighbors' places.

All three of these responses assume drywall-to-drywall construction, which is common but not universal. If you're in an older building with brick, concrete block, or plaster-over-lath, the penetration math they're citing shifts. HST through old plaster and brick goes further than through modern drywall. That matters for your neighbor liability, which I'm guessing matters to you.

Same thing if you've got shared structural walls or party walls. Some apartments have actual fire-rated separation between units—some don't.

I ask because I landed on a 9mm carbine too, but for a different reason than capacity or recoil: **I could actually verify it wouldn't go through my walls into the unit next door.** We have concrete block with some offset stud cavity, and I tested Federal HST through samples of that exact construction before I called it good. Took an afternoon with a ballistics gel box and cardboard. The round still penetrated, but not far enough to be a reasonable neighbor risk.

Without knowing what you're shooting *through*, you're making the decision half-blind. If you're in drywall-only construction, yes, the 9mm wins on penetration. If you're in something heavier, you might have less to worry about either way—which changes whether you even need a carbine versus a shotgun.

What does the wall between you and your neighbors actually look like? That's the question that needs answering before you buy anything.