Self-defense handgun discussion circles around the stopping power, although the actual construction issue is how to balance reliability, penetration and shootability under stress. In case any of those legs give way the entire platform may become a loser-notwithstanding what a caliber has accomplished on paper or in the pet story of a friend.
Certain cartridges perform poorly due to being mechanically less dependable, certain due to failure to reliably get up to critical depth, and certain due to recoil and blast violence penalizing accuracy during a short period of time. The reasons why the calibers below appear on the testing and training discussion again and again are because of those very reasons.
A little fact is forgotten in caliber arguments: when the first blow falls it can be a rap. The first-shot accuracy has been demonstrated to be enhancing with controlled breathing, as have 9 studies in which tactical breathing positively affected first-shot scores by an average of 1.9 points in a simulator (tactical breathing increased first-shot accuracy). And that is-not the less-when the cartridge is already bordering on the fringes.
1. .22 Long Rifle (.22 LR)
The reason why 22 LR is everywhere is its low recoil and easy-to-shoot characteristics; however, its use as a defense weapon has two structural flaws: ignition stability, and low performance margin. The rimfire priming is spread across the rim, and even where a dent may appear perfect, ignition may still be problematic because of rim thickness variation, bolt/breech interaction and firing pin energy, which is common in high-volume fire (rimfire ignition variability). With centerfire systems, much of that is avoided using a discrete primer in a protected pocket (centerfire primer design).
Although the gun can be functioning well, even with a perfectly functioning gun, when the angles, clothing, and non-perfect hits are present, the . 22 LR can easily be found falling beneath the energy and penetration cushion that the defensive ammunition attempts to provide. It may be fatal, but offers insufficient mechanical assurance to fulfill a job that requires it.
2. .25 ACP
25 ACP was to provide centerfire on pocket pistols but not centerfire makes a cartridge that is repeatedly underpowered worthy. Being able to carry very small projectiles and having limited velocity, it does not have much space to continue penetrating once it begins to interact with bone, heavy clothing or less than ideal shot paths.
Numerous pistols fired in the .25 ACP caliber date also to a period (and dimensions) in which sighting systems, trigger features, and realistic accuracy may be impaired. The fundamental problem with the cartridge lies in the fact that, despite all the things being just perfect, the output of the cartridge is still nearly touching the floor.
3. .32 ACP
32 ACP is reputed to be shootable, and it is true, low recoil is an aid to hitting the target. The difficulty is consistency at the end stage. Expansion is intermittent at velocities of.32 and where expansion occurs it can rob penetration which was already shallow.
Its past popularity does not necessarily correspond to contemporary defense strength particularly when weighed against service calibers designed with deeper penetrations goals and barrier excellence. Practically, it is frequently an exercise between comfort and capability that most defensive carriers simply do not have to confront with.
4. .410 Shotshell from Revolvers
Compact .410 revolvers suggest that a handgun can have the answer of a shotgun but it is the physics of small bore shotshells and short barrels that are to be blamed. Pattern spread dissipates the shot and most loads of birdshot do not offer the depth required to make dependable hits on threats. Buckshot and slugs may work better, yet they are still reduced in regard to efficiency and unpredictable outcomes compared to handgun loads.
The greatest risk of the platform is the illusion of safety: the spread does not feel like a real defensive blow, but actual defensive hits still require that the shots be directed, and terminal performance requires enough penetration.
5. .380 ACP (weak or badly matched loads)
According to 380 ACP can function, the caliber is susceptible to the length of the barrel, shape of the bullet, and velocity. Certain loads are unable to provide the penetration which defensive requirements attempt to provide, especially with very short pistols. Once it occurs, the primary strength that defines the .380 as compact carry begins to clash with its primary weakness that is the low ability to provide performance buffer.
The engineering lesson here is that .380 is not necessarily bad but it is more punitive to ammunition indiscrimination than service calibers. A marginal load is a reality in a cartridge that already has lean running on it.
6. 10mm Auto
10mm Auto cannot be taken lightly and that is the same reason why this power landed in this list. The high impulse of recoil, the muzzle blast and the possibility of over penetration makes it difficult to defend the population at such places and indoors. Squeezy shots can also enhance error in shooter when subjected to stress increasing the lagging shots as well as widening the cliques.
That is, 10mm can fluidly turn the issue of terminal performance to that of human performance. A cartridge that seems more energy-wise nice may prove inferior in actual performance in the degradation of accuracy and control.
7. .38 Special out of ultra-short barrels.
The snub-nose revolvers are associated with a high cost in terms of velocity penalty and 38 Special has a rich history of defense. Such a loss of velocity is significant since most hollow point relies on velocity to enlarge, and any failure to enlarge or partial enlargement may alter not just the penetration but the wound dynamics.
With the shooters pursuing performance with +P loads in very small revolvers, they tend to experience a recoil spike without a corresponding terminal gain. The outcome may be an easy to carry, but difficult to shoot well, carry gun that is useful in quick, accurate strings.
8. .44 Magnum
44 Magnum is designed to be high energy and deep penetrating and these two features are a liability in everyday defensive scenarios. The blast and recoil decelerate accurate follow up shots and the size of the gun that is usually linked to the cartridge will decrease disguisability and ease of use.
The penetration so deeply also increases the risk of bystanders in the house. Over-penetration and unpredictable pass-through is still an actual issue in testing discourse, though with modern defensive bullets, even in testing, it is found that a few loads of a handgun are able to pass through a target analog and travel downrange (a 9mm load passed through a ballistic dummy).
The choice of caliber is never a search of the largest number; it is a search of recurrent performance in times of unseemliness in mechanics and physiology. The above cartridges are prone to failure, either too marginal, too inconsistent or too punishing all three.
For most defensive roles, the durable middle ground remains the most technically defensible: a reliable centerfire platform, a duty-proven cartridge class, and a load that balances penetration with controllability.
