“A caliber used in home defense should not be an exotic or extreme one, it must be reliable, controllable, and be able to deliver terminal performance consistently when circumstances are messy (awkward angles, low light, heavy clothing, and adrenaline).
Other cartridges omit that mark because of predictable reasons: rimfire ignition which is less reliable by nature, loads which have trouble hitting the 12-18 inch FBI penetration standard, and recoil and blast that complicate accurate follow-up shots as they should be.
This list divides eight calibers instructors and ballistics-conscious handgun shooters habitually label as poor options as primary defensive handguns and what is more likely to work.
1. .22 Long Rifle (.22 LR)
The reason why 22 LR is everywhere is that it is simple to shoot and it has a low recoil, low noise, and cheap to practice. The thing is that it is rimfire. That is, ignition relies on a thin priming compound that has been spun as a rim, and misfires are a fact to be taken into account as opposed to center fire cartridges.
At the extreme, most .22 LR handgun ammunitions have an energy of less than 200 ft-lbs and often fail to penetrate reliably even when shot through heavy clothing. Can be lethal and predictably stops a threat do not belong together in a defensive context. A .22 can also come in handy with recoil-sensitive shooters, yet it demands a number of hits and accurate positioning.
Safer options: .22 magnum in a suitable platform, or one can even step to a service caliber of 9mm with trustworthy defensive ammunition.
2. .25 ACP
In 1905, 25 ACP came to provide tiny pistols with a centerfire option, but it has been outdone decades in the past. The standard muzzle energy is less than 70 ft-lbs, and the space available in modern hollow-point designs is less than that.
A large number of the handguns of .25 ACP are also ultra-minuscule with only a few sights and short grips, which does not augur well with practical accuracy, the one thing low-powered cartridges can ill afford to lose. The problem is aggravated by the lack of modern ammo in the selection.
Less unsafe options:.380 ACP where defensive ammunition has been vetted, or 9mm in a small handgun.
3. .32 ACP
The 32 ACP is in an uncomfortable place it cannot shoot as hard as most service rounds, and does not always provide the reliability of penetration and expansion that is now expected. The thing is that in the real world performance may collapse where bullets are plugged with cloth and not all guarantees that its loading will act as modern duty bullets.
The cartridge can be fairly comfortable, but not very high-performance, with muzzle energies of about 125170 ft-lbs. The issue of comfort is important, although defensive guns must have sufficient amount of working margin to deal with un-perfect shots and conditions.
Less risky options:.380 ACP using short-barrel-optimized defensive ammunition, or 9mm using modern JHP designs.
4. .410 Shotshell Out of a Revolver
The attraction is clear: a handgun throwing a pattern. The fact is, that short barrels are tough on the performance of shotshell. A revolver-length barrel can not provide the penetration necessary to strike vital structures and even buckshot/slug is usually not as penetrative as special purpose defensive handgun cartridge.
Dissemination of energy is also found in pattern spread. The load can produce a distribution of pellets where they make pictures in a cardboard box but that does not become stopping power when used on a determined attacker, instead of concentrating the damage where it is needed.
Safety Picks:.38 Special (in a suitable barrel length and load) or 9mm/.40/.45 in a controllable platform with established ammunition.
5. .380 ACP With Low-Performance Loads
380 ACP does not necessarily make a bad defensive caliber, just that it is one of those that can be easily misused. Most popular loads, particularly of short barrels, do not penetrate sufficiently, and an average cartridge becomes a gamble.
Even small.380 pistols may feel unnaturally snappy, which undermines the primary reason why users prefer to use.380 in the first place; controllability. The cartridge requires greater discipline in the choice of loads as well as more honest practice to guarantee reasonable performance.
Neither as harmful: .380 ACP with loads than known to penetrate well with short barrels, or increasing to 9mm in a similarly-sized handgun provided it can be controlled.
6. 10mm Auto
10mm Auto is no lightweight, typically with 600+ ft-lbs of horsepower, but the performance is accompanied by great recoil, loud bang, and the risk of over-penetration in normal home construction. The recoil and muzzle rise spike slow, flinch or miss more often in a stressful situation, and the shooters miss more often more often, and instructors regularly observe this.
Power is a characteristic in the woods. At the corridors, it may be a liability when it distorts accuracy or propels rounds out of where they are supposed to hit. To the majority of households, the cartridge capability is much beyond the problem set.
Safety substitutes: 9mm, .40 S&W, or .45 ACP with current defensive JHP bullets.
7. .38 Special From Ultra-Short Barrels
The earned reputation of 38 Special is different, however, when it comes to snub-nose revolvers (less than 2 inches). Loss of velocity may inhibit the expansion of hollow points, and +P loads often generate recoil and burst without providing similar terminal advantages of the small barrels.
Snubs are also not easy to shoot excellent compared to their size: tiny grips, lengthy triggers and brief sight radii. When the platform is already challenging, it is further increased by combining it with a load not only performing poorly when short barrels are involved.
Less lethal options: .38 Special rounds designed to fit short barrels or a small 9mm pistol in case the shooter can reliably run it.
8. .44 Magnum
The reason is that 44 Magnum can generate 1,000+ ft-lbs of energy and give a maximum possible penetration. The same characteristics are its enemies within the house. Follow-up shots are slowed by recoil, muzzle blast is very sharp, and the chance of punching through several interior barriers is greater with high-energy loads.
The full-size revolvers in which it is loaded are also more difficult to pack away and many shooters cannot hold and control quickly. In the large majority of home-defense layouts, it is merely as cartridge as the surroundings demands.
Substitutes that are safer: .45 ACP, 9mm or .40 S&W with some contemporary JHP loads that are selected to be balanced in penetration and expansion.
Caliber choice is ultimately about stacking the odds: dependable ignition, consistent penetration, manageable recoil, and the ability to put accurate rounds on target quickly. Most defensive problems are solved by control and repeatability, not maximum power.
For many shooters, modern 9mm, .40 S&W, and .45 ACP defensive loads land in the practical sweet spot especially when paired with a platform that can be run confidently under stress.
