A contemporary carry pistol seldom “goes off” or “just quits” in the first place. Majority of failures are revealed earlier- in configuration selections, ammunition compatibility and those trivialities of handling, which are simply innocuous until they are not.

Covering the concealed-carry culture is the quest of a handgun “best”, whereas the question to pose more importantly is the engineering question: what makes a small handgun act like a full-size gun when it counts: a consistent grip, a consistent trigger press, a consistent recoil, a system that remains in place on the body. The handgun is not the only element in that system and the trigger finger of the shooter is a very small part but has the greatest leverage so many times.
This is kept down to earth by safety training. The regulation remains minimal, but a single sentence has an out-of-proportion weight: lack of trigger-finger discipline is the key factor in a negligent discharge. The physical fact itself is uncomplicated: that a modern gun generally requires mechanical operation to be discharged, and a mechanical breakdown leading to an accidental firing is very rare. That reinforces the issue of holster selection, drawstroke training and “finger high, frame indexed” habits as more than etiquette, and they are engineering controls, to counter predictable human error.
Meanwhile, reliability is where market has had a silent over performance. Micro-compacts and compact 9mms are now operating with a degree of durability which would have been an implication of duty-grade not so long ago. A popular stress run test passed a Hellcat-pattern pistol through extremely high rounds and it had not become a diva, and another compatibility test was able to have 2,500 rounds of 21 loads across 21 cases running on two Hellcat Pros without failure. What is more significant is not the brand name, but the principle, which is that small guns may be mechanically reliable, by which they require the user to verify that the exact ammunition that he or she intends to carry actually works in their own pistol.
It is a lot of ammo that most of the “best-gun” arguments rest on. Recoil effect and point-of-impact movement vary with bullet weight and velocity, and both effects occur more quickly in short-barreled pistols. Other trainers suggest training with a load weight similar to that of carry recoil; an example of a heavier, more stable simulated range would be Federal American Eagle 147-grain FMJ. The thing is consistency: the shooter that practices with one feel with another shooter is creating a hidden mismatch into his/her draw-to-first-shot firing schedule.
Another dimension of reality checking is through ballistic testing- particularly with tight barrels where performance is ammunition-dependent. On a controlled gel test with an M 2.0 Metal Compact and Federal Punch 124-grain 9mm, penetration was found to be 17-18 inches, remaining within the window commonly cited by FBI and exhibiting regular expansion. Such data will not substitute the purpose testing of the actual carry gun, but it does demonstrate what designed to work will look like in conditions where the variables are controlled.
The last item that makes a good pistol a good system is carry method. Appendixing inside-the-waistband has become popular due to its staying fast when on foot, or sitting down, and to the ease with which the weapon can be used in tight spaces. It also exaggerates laxness: muzzle positioning on holstering, holster mouth stability and rigidity of belt/clips. Formal options of hardwares like metal clips, claws/wings, wedges are not fashion accessories; these are leverage and geometry devices that hold the grip in place, the holster in place, and the draw repeatable.
Ultimately, the question of the best concealed carry gun reduces to what is less exciting and more practical, namely, what pistol fit the hand, operates on the selected carry load, and can be carried on a daily basis in such a configuration that the trigger remains covered and the presentation remains acceptable. It is not just a model, but rather the degree to which the entire system can be brought to act in a manner that is engineering wizardry.

