Handgun fights are hardly square-range drills. Guns come between, thick clothes absorb the strength, and a bullet which halts short becomes a non-stop instead of a solid shot.
This is why long-established benchmark is not concerned with “stopping power” slogans. It is matter of whether the projectile can consistently hit what matters. The usually mentioned window is the 12-18 inches of calibrated ballistic gelatin that is provided to make up of bad angles, barriers and imperfect circumstances.
There are others that are interesting, historic, or mechanically entertaining. As a defense they may be a trap too.
1. .22 Short
22 Short, however, is almost as ancient as the firearm itself, and the only contemporary issue about it is this: it comes with very little energy and loses penetration quickly. Out of the barrels of handguns, velocity decreases such that findings begin to start shallow tracks and inconsistent disruption, particularly when clothing and bone are introduced. Practically, it imposes a constraining requirement: ideal location with minimal allowance against real-world angles. That is a hard-knuckle to any cartridge that is supposed to operate in a stressful situation.
2. .25 ACP
The strongest case that 25 ACP can present is ignition. Being a centerfire cartridge, it does not fall into the pit of rimfire which can be marked in that priming compound distribution may create more duds. It is terminal performance: in gel work with pocket pistols,.25 ACP loads regularly fall short of the penetration depth most testers are seeking, and the expansion can tend to aggravate the situation. Only one .25 ACP load in one commonly quoted series of pocket-caliber gel could get all five rounds out of the test gun over 11 inches, and even then it is down to the normal standard.
3. .32 S&W (original)
The early .32 S&W was designed in a time of small revolvers and other things. Its bullets are slow and lightweight and can easily be overtaken by the later rounds of the .32 family and when barriers get involved the picture changes. It is a collection cartridge with a living heritage, yet current defensive requirements increase speed, reliability, and the skill to drive as far as possible on irregular positions places in which this round lags.
4. .410 bore from a handgun
An easy solution appears to be a short-barreled.410 revolver: several projectiles, large muzzle, point-and-shoot feels. The fact is that spread does not in any case substitute penetration and that pellet performance may crater when a heavy clothing is put on. Although separate pellets may become very decent in thickness in bare gel the process depends upon a large number of small wound tracks rather than on one track that is continually sufficient. One of the lessons that testers have learned when comparing the energy of pellets is that any projectile can act like a small pistol bullet rather than a fight-stopping slug, particularly when using short handgun barrels.
5. .22 LR (from handguns)
Handgun length barrels and rimfire ignition are also leading to two headaches simultaneously: low velocity and low reliability. Rimfire cartridges burn when the firing pin squashes the rim of the case, this design is less reliable than centerfire design cartridges by nature since the distribution of the priming compound is less uniform.
Performance varies with barrel length is also indicated by gel testing of short barrel.22 LR. In a test set of pocket-caliber, a test was performed in which the same test barrel was changed to a 1.9-inch barrel, and then in the same set to a 4.4-inch barrel and the result was an increase of 126 fps but the velocity did not always give the highest penetration. It is the issue of that randomness.
6. .380 ACP
380 ACP is existing on the verge of enough and the precipice is performance consistency by clothing. Most loads either undergo due penetration with slight expansion, or they exhibit apparent expansion with short penetration. Only a small slice of.380 loads can reliably combine both characteristics in large-scale hobbyist gel programs meant to recreate the heavy-clothing segment of FBI-style testing.
That does not render the caliber useless, it simply makes it very easy to misuse particularly in micro pistols whereby most emphasise is on velocity and the design of the bullet.
7. .45 GAP
The exceptionally uncommon defensive caliber is 45 GAP, which did not pass due to physics more than the logistical factor. It was created to mimic the performance of a .45 ACP with a shorter case in smaller grip frame, and provided performance close to that, although it was never widely adopted. Defensive carry: niche chamberings result in a silent risk: a smaller selection of firearms, a smaller selection of load, and a smaller opportunity to validate performance with the broad selection of modern bullet designs. That lack of reliability is its own punishment in a field where reliability and repeatable testing is important.
These are the penetration, but that is the only condition that cannot be compromised with once the trigger is broken. The lesson of gelatin and barrier work is always the same, shallow, patchy players do not improve under any kind of pressure they grow less indulgent. To anyone who is deciding on a defensive handgun configuration, the most helpful filter is not interesting by design: proven penetration with reproducible performance, preferably confirmed in test protocols, which incorporate heavy clothing and short-barrel velocities.
