Recoil and muzzle blast: The 10mm is a handful, while the 9mm is a pussycat
Recoil can be a significant factor when you’re selecting a handgun, particularly for defense. The 9mm has much less recoil than the 10mm, typically one-half to one-third the amount (common 9mm loads produce between 4 and 8 ft/lbs of recoil energy, while common 10mm loads produce between 10-12 ft/lbs, and sometimes significantly more, depending on the load). More recoil translates to more time between effective follow-up shots, even with experienced shooters, as well as an increased potential for the shooter to develop a “flinch” that can hinder accuracy. The FBI found that the 10mm Auto was too much for about 90% of its agents, who were unable to effectively handle the larger, heavier pistols and the stout recoil produced by the full-power 10mm cartridge. The organization downloaded the 10mm to try to solve the problem, which is the primary reason for the birth of the .40 S&W (often jokingly called the “forty short and weak”) that the FBI adopted and used for the next couple of decades, before eventually switching back to 9mm as better bullets became available.
Muzzle blast of the higher-pressure 10mm loads can also be punishing, which is a factor in defensive situations where you may be inside your home and will almost certainly not be wearing ear protection.
Self-defense: Terminal ballistics are nearly identical; 9mm guns are smaller and lighter
“Any serious self-defense cartridge must start with a 4,” according to some memes and long-held beliefs. This stems from the poor performance of .38 caliber bullets against determined adversaries in the early 20th century, as well as the mythical inability of military 9mm FMJ loads to adequately stop opponents. If you’re comparing .45 ACP ball against a 9mm ball, there may be some evidence to suggest that the larger bullet might perform a little better (though the evidence is generally spotty and, truthfully, all handgun FMJ/ball ammunition performs relatively poorly as a “manstopper”). However, since the 1990s, there have been many improvements in projectiles and bullet performance in defensive calibers, and in objective comparisons of “stopping power” in real shootings with center thoracic hits, all of the popular defensive and police calibers (9mm, .357, .40, 10mm, and .45) using modern bullets have performed almost identically.
If we accept this evidence, then 9mm starts to show distinct advantages when compared to 10mm for defensive use against human threats. There has been a large number of truly small, packable 9mm CCW pistols hitting the market over the past few years, which helps the argument further. After all, if 9mm and 10mm perform basically the same against human attackers, why put up with the greatly increased cost, blast, recoil, weight, and size of a 10mm?
So, which is better, 9mm or 10mm? For plinking, target shooting, competition, and self defense, the 9mm is the winner. For bear/dangerous animal defense, hunting, or “go-big-or-go-home” blasting for fun, the big ten is the obvious choice. What would we recommend? Well, when it comes to firearms, our usual advice is, “Why not get both?”
