I had an epiphany awhile back that the idea of knockdown power for defensive handguns might be a holdover from hunting, where it’s important to bring “enough gun” to humanely drop an elk or some other big critter in one shot. For long guns, “Knockdown power” is a very real thing, given the amount of force that a centerfire rifle drops onto its target. Considering, however, that there isn’t NEAR as much variance in body mass between two humans as there is between, say, a coyote and a bear, and that any centerfire rifle is going to thump much more than any centerfire pistol, I think the “knockdown” effect of 9mm vs. .40 and .45 is pretty moot.
Wanting some more input from someone in the industry who’s not just a schmuck with a website like myself, I reached out to Matt DeVito of DownRange Firearms Training for his thoughts on the matter.
Hey, Matt, quick question,
I know Rob (Pincus) prefers 9mm over .40 now: What say you, and what is your feeling about “knockdown power” versus follow-up shots?
9mm is preferred over .40 and .45 for a few reasons. First reason being magazine capacity. Look at 3 guns, Glock 17 (17+1), Glock 22 (15+1), Glock 21 (13+1). In a world where people think that “knockdown power” is a real and viable term, 9 out of 10 people would choose a .45. However, knockdown power, aside from being internet lore, is complete bullsh*t. No pistol round in history was ever designed to take a man off his feet. Bullets are used to “stop” a threat by 2 methods, physical, and psychological. A physical stop essentially is that you’ve shot the attacker, usually multiple times, and they have ceased the attack. A psychological stop is when you draw the gun, shoot attacker, attacker says “Oh %@#, I’ve been shot,” runs away and the cops find him behind a dumpster 5 miles away after he’s bled out.
All that aside, handgun bullets do maximum damage by “cutting” through soft tissue, tendons, ligaments, and destroying bone and muscle. There’s two types of wound tracts, temporary and permanent. You are looking to maximize permanent wound cavity. Permanent, (if you look at a block of ballistics gel, it is essentially the pieces that are irreparable), temporary is the damage done by the “shockwave” as the round passes through something, but again like in a ballistics gel test, will bounce back into place.
Also it’d be good to note that most “bare gel tests” are just that; bare gel and not representative of flesh as theres no bone/muscle involved. We just did a ballistics text on a pig recently; all the rounds performed the same minus the .40 which was actually the worst performer.
And no matter the caliber, its been proven that modern bonded hollow point is the round you want and is the most consistent performer even through intermediate barriers
As far as “defensive” handgun rounds go we group then into 3 categories
VIABLE: .380, .38, 9mm, .357mag, .40, .45, 10mm.
RECOMMENDED: 9mm, .40, .45,
Which kinda falls in-line with my feelings as well. Sure, that “Don’t bring a gun to a gunfight unless it has a caliber that starts with ‘4’.” talk sounds all macho and stuff, but I’d prefer to be alive with my nine than dead with a .45 in my hand…