3 Myths About Handgun Stopping Power

We need to talk about stopping power because there’s a lot of garbage floating around. Misinformation that might get you hurt. Or worse, make you overconfident in your carry gun’s ability to end a fight instantly.

Let me clear something up right now. Medical professionals experienced in evaluating gunshot wounds often cannot distinguish between wound paths from common handgun calibers during surgery or autopsy. That’s from the FBI’s own ballistic research. Not internet forum experts. Not gun shop commandos. Actual doctors.

Training matters more than caliber debates. The best stopping power comes from putting rounds where they need to go, not from picking the biggest bullet.

So, when someone starts going on about how their .45 has “superior stopping power” to your 9mm? They’re likely selling you nostalgia, not facts.

Myth #1: Bigger Caliber Equals Better Stopping Power

This is probably the most persistent myth out there. Walk into any gun shop and you’ll hear it. “Real men carry .45 ACP.” “9mm won’t stop anyone.” “I carry a .45 ‘cause they don’t make a .46.”

Here’s the problem with that thinking.

A 9mm bullet expands in ballistic gelatin, showing penetration depth and wound channel characteristics. Handgun stopping power myths often ignore actual terminal performance data. The FBI testing protocol requires 12 to 18 inches of penetration. Modern hollow points expand reliably in calibrated gelatin. Defensive ammunition must perform through barriers like clothing. Penetration depth determines whether bullets reach vital organs. Expansion creates larger permanent wound channels. The 9mm meets FBI standards consistently. Shot placement remains more critical than caliber selection. — Ballistic gelatin shows what a bullet actually does after impact. Penetration depth and expansion matter far more than caliber bragging rights. Image: Hornady Mfg.

Real-world incidents have documented people failing to stop attackers with .45 ACP while others have stopped threats with a single shot of .22 LR. I’ve read incident reports where subjects took multiple hits from .40 S&W and kept fighting. I’ve also seen documentation of .22 caliber rounds completely incapacitating someone. And, of course, I’ve seen plenty of cases where the bigger bullet did an excellent job.

The relationship between bullet size and immediate incapacitation isn’t linear or guaranteed.

What matters? Shot placement. Penetration depth. Whether you hit something the body absolutely needs to keep functioning.

The FBI spent years studying this after the 1986 Miami shootout. So have hundreds (thousands?) of other agencies, organizations and people. While theories vary, the majority of research supports the idea that the most effective way to stop an attacker with a handgun is to deliver multiple rounds quickly into vital areas.

Speer Gold Dot 10mm Auto self-defense ammunition in a box displaying cartridges with hollow point bullets. Handgun stopping power myths overstate caliber importance in defensive shootings. The 10mm Auto delivers higher velocity than most service cartridges. Gold Dot bullets expand reliably through clothing and barriers. FBI penetration standards require 12 to 18 inches in gelatin. Premium defensive loads perform consistently when designed properly. Modern ammunition technology improved expansion reliability significantly. Shot placement determines effectiveness more than cartridge selection. Training with carry ammunition ensures reliable function. — Quality defensive ammunition like Speer Gold Dot meets FBI penetration standards across calibers. The 10mm Auto brings more energy to the table, but shot placement still rules. Image: Speer

Some rounds correlate with higher degrees of success. In general, popular handgun cartridges loaded with modern hollowpoint bullets — like the 9mm, .45 ACP, .40 S&W and .357 Magnum — all correlate with good performance when controlled for shot placement.

None of this is to say that the .45 ACP is ineffective. Quite the opposite — the .45 remains a solid choice for self-defense. However, your .45 doesn’t matter if you can’t hit vital structures. Practice and training remain a decisive factor.

Myth #2: Handguns Have Knockdown Power

This one comes straight from Hollywood. Bad guy gets shot. Bad guy flies backwards like he caught a fastball to the chest.

Except that’s not how physics works. The momentum of a .45 ACP bullet is not enough to physically knock down an adult who’s moving toward you.

An expanded Federal HST 44 Magnum bullet displays full mushroom shape after penetrating ballistic media. Handgun stopping power myths suggest larger calibers guarantee immediate incapacitation. The 44 Magnum generates significant velocity and energy at the muzzle. Federal HST bullets expand consistently through barriers and clothing. Hollow point petals increase permanent wound channel diameter substantially. Penetration depth must reach vital organs for effectiveness. Expansion alone does not ensure rapid threat neutralization. Shot placement to critical structures ends defensive encounters. Modern bullet engineering maximizes terminal ballistics performance. — Federal HST expansion looks impressive, and the .44 Magnum delivers serious terminal performance. But even this won’t guarantee instant stops without getting a good hit. Image: Federal Ammunition

If a bullet had enough energy to knock someone down? The recoil would knock you down, too. Conservation of momentum isn’t just a suggestion. It’s physics.

What actually happens when someone gets shot and goes down immediately? Usually one of two things. Either you hit their central nervous system and they physically cannot continue. Or, they choose to stop fighting because they’re injured, scared, or realize the situation has changed.

That second one? That’s psychological incapacitation and not physical knockdown power.

Even fatal wounds don’t guarantee instant stops. The body can keep functioning on residual oxygen in the blood. On adrenaline. On sheer determination.

Only hits to the central nervous system are likely to cause immediate physical incapacitation. Everything else is penetration, blood loss, and time. Time you might not have.

This is why training emphasizes multiple shots. Why we practice failure drills. Why “shoot until the threat stops” is the standard guidance. Because handguns — all handguns — require good shot placement to work quickly.

Myth #3: Modern Hollow Points Guarantee Immediate Stops

Premium defensive ammunition has gotten incredibly good over the past three decades. Expansion is more reliable and penetration depth is more consistent. Barrier performance has improved dramatically.

However, good ammunition doesn’t equal guaranteed stops.

Hornady Critical Defense 9mm ammunition box with cartridges showing red polymer-tipped hollow point bullets. Handgun stopping power myths dismiss 9mm effectiveness despite real world data. Critical Defense features Flex Tip technology preventing hollow point clogging. The polymer insert initiates expansion through heavy clothing reliably. Nine millimeter offers higher capacity than larger caliber alternatives. FBI research supports 9mm as an effective defensive cartridge choice. Penetration depth meets the 12 to 18 inch standard consistently. Modern ammunition technology closed the gap between calibers significantly. Shot placement determines outcomes more than bullet diameter alone. — Hornady Critical Defense is built to work through heavy clothing without clogging. The 9mm gives you capacity and controllability — now, get to the range and train. Image: Hornady Mfg.

Here’s what modern hollow points do well: They penetrate to adequate depth (12-18 inches in ballistic gelatin) while expanding to create larger permanent wound channels. Compared to ball ammo, they’re less likely to overpenetrate and hit unintended targets. Compared to traditional, old school hollow points, they perform more consistently through barriers like clothing, drywall, or auto glass.

While great, the do not magically incapacitate attackers on contact.

Many people shot with handguns survive. That’s across all calibers and all bullet designs. Modern defensive rounds have absolutely improved our odds in self-defense situations, but they haven’t changed the fundamental reality that handguns are relatively weak tools compared to rifles or shotguns.

Person shooting a pistol with flash of fire out the barrel — While handguns can be extremely capable defensive tools, power alone is not the only consideration. Proper shot placement and capability for fast follow-up shots if needed are equally important.

The FBI’s testing protocol revolutionized defensive ammunition evaluations. Ammunition must penetrate 12-18 inches through ballistic gelatin and various barriers to pass FBI standards. This gave us ammunition that works far better than what was available in the 1980s and earlier.

But “better” doesn’t mean “perfect.” It means your carry ammunition will likely perform as designed if you do your part. It means you have a fighting chance with proper shot placement.

The ammunition isn’t the weak link anymore. The shooter is.

Man shooting pistol in self-defense while carrying a backpack — Are you prepared to deliver threat-stopping firepower? If you carry, you must have the proper mindset and training to respond appropriately if faced with an unavoidable threat.

What Actually Matters

If stopping power is mostly a myth, what should you focus on?

Shot placement. This is the single most important factor in defensive shooting effectiveness. Stopping power correlates more with shot placement than with any particular round. Hits to vital structures — heart, major blood vessels, lungs, central nervous system — are what end fights quickly.

Penetration. Your bullet needs to reach vital organs. That means adequate penetration through clothing, barriers, and tissue. Too shallow, and you’re poking holes without hitting anything critical. Too deep and you risk overpenetration.

Hornady Critical Duty 45 ACP bullet penetrates 14 inches in calibrated ballistic gelatin showing ideal depth. Handgun stopping power myths focus on caliber instead of penetration adequacy. The FBI testing protocol established 12 to 18 inches as optimal depth. Fourteen inches reaches vital organs through clothing and tissue reliably. Critical Duty ammunition features FlexLock bullets for barrier performance. Controlled expansion prevents excessive overpenetration through targets dangerously. The 45 ACP remains a proven defensive cartridge when loaded properly. Penetration matters more than temporary cavity size in handguns. Shot placement to vital structures ends encounters decisively. — Fourteen inches of penetration puts Hornady Critical Duty right in the FBI’s sweet spot. Deep enough to reach vital organs, controlled enough to minimize overpenetration risk. Image: Hornady Mfg.

Capacity. More rounds means more chances to get good hits. It means you can continue engaging if your first shots don’t work. It matters in multiple-attacker scenarios. Don’t sacrifice capacity for minimal gains in terminal ballistics.

Reliability. Your gun and ammunition need to work every single time. Malfunctions in a gunfight are catastrophic. Test your carry ammunition. Make sure your gun runs it reliably.

Training. This matters more than anything else. The ability to draw quickly. To get your sights on target under stress. To make good hits while your hands are shaking and your heart is pounding. None of the other factors matter if you can’t execute under pressure.

The Bottom Line

Handgun stopping power — as most people discuss it — is largely a myth. There’s no magic caliber. No instant off-switch. No guaranteed one-shot stop.

What we have instead is this: Modern defensive ammunition in common calibers (9mm, .40 S&W, 10mm Auto, .45 ACP) all perform adequately when you get good hits on vital targets. The differences between them are marginal. Real world performance data supports this.

Woman holding a pistol — With proper training and a high-quality firearm — as well as a safe means to carry it — you have built the foundation of a sound defensive system.

Choose a caliber you can shoot well. Pick quality defensive ammunition that meets FBI penetration standards. Then train relentlessly on getting fast, accurate hits under stress.

Because at the end of the day? The gun that’s with you, that you can shoot well, with ammunition that penetrates adequately — that’s what gives you the best chance of surviving a deadly force encounter.

Not magical stopping power. Not the biggest bullet. Not the fanciest ammunition.

Just fundamentals. Shot placement. Multiple hits. Training. Everything else is a distraction.

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