The internet is no stranger to the caliber wars. 9mm was meant to wound Europeans, to kill anything you need a 45! The 5.56 poodle shooter doesn’t have the energy at the muzzle that a 7.62 battle rifle delivers at 500 yards! Bigger holes bleed more! Velocity is a diminishing investment, but mass and diameter are constants!
You want to know the truth?
Most of the people in the caliber wars have either never shot someone, or seen someone shot. I’ve never shot someone, but I have seen someone shot. With an AK. He was luckier than the other guy shot with an AK who died.
What does this tell you about the effectiveness of the AK? Absolutely nothing. Within normal use ranges, all bullets are sufficiently deadly if you are sufficiently skilled.
Now there are some cartridges at the “weaker” end of the lethality spectrum that I don’t recommend for anything other than sport shooting or plinking. The 25ACP? Perfectly suited to assassination ranges. I’ve watched a 22 Short literally bounce off standard 16 gauge sheet metal (my wife missed the target and hit the shed). But that was at 55 feet downrange, and I sure as heck don’t think my skull could stop a 22 short at close range.
At the other end of the spectrum, a 50 BMG is probably a bit on the unnecessary side, as is anything 308 Win or more on the energy spectrum.
Rule of thumb here, humans are pretty equivalent to “deer size game” when you consider small Cous Deer to big western Mule Deer. The classic deer cartridge is the “sedate” 30-30 Winchester.
There aren’t many handgun rounds out there that can perform anywhere near the level of energy and velocity as the sedate 30-30. Quite literally the difference between the 10mm and 380 ACP is larger diameter and heavier bullets for similar speeds. A shot to the head with either is going to ruin your day, and a shot to the foot with either is going to ruin your day. The larger 10mm is going to put up more impressive energy numbers, but it doesn’t do jack if you can’t put that bullet where it needs to. After all, the 30-30 isn’t going to kill with a miss.
So what does going to a more powerful round give you? The more powerful round gives you a slightly better range options, and better options for turning cover into concealment. That comes at the cost of increased recoil, muzzle flash, noise, and weight. There ain’t no such thing as a free lunch.
Lately, you know since about the Vietnam war or so, folks have been beating up on the 5.56 in various forms. The idiotic “Is Mk318 better than M855A1?” question really makes me want to ask, “are you volunteering to get shot with both to see which you’d prefer?” But the introduction of rounds like the 6.8 SPC, 6.5 Grendel, 300 Blackout, and 6×45 (actually a really old wildcat), implies that the market feels the 5.56 just isn’t up to it any more.
You know why new cartridges are invented? To sell rifles. In order to sell rifles someone has to convince you that the rifle you have now is a tad inadequate in some department. So cue the “has more energy at 500 than the 5.56 at the muzzle!” or “Beats the 308 win in ballistics out to 600 with less recoil, ALL from an AR-15 package!”
The cartridge wars are about brand loyalty and marketing, nothing more.
Now every once in a while you will find a very specific need that only a few cartridges can fulfill. Like the 357 Sig being chosen because it could launch projectiles fast enough to penetrate Chicago transportation seats to get bad guys. Makes perfect sense for that organization to choose that caliber for that reason. That’s not a consideration for the Piedmont North Dakota SWAT Team and competitive fishing league.
Currently the Army is looking for another handgun to replace the M9. There is nothing wrong with an M9. It’s an older design, not a polymer striker fired option like a Glock or M&P, but in terms of putting ventilation holes in stuff, it does fine. In fact, the medical examiner isn’t going to be able to tell what brand of pistol was used to ventilate someone. Why is the Army looking to replace the M9?
Because the Army is stupid, and because the Army is changing. With opening up all jobs to females now you’ve got all sorts of hand sizes and shapes to deal with. Rather than training people to adjust themselves to use the tool, they are searching for a tool that can be more easily modified to adjust to the user. Nothing wrong with that approach, just that it will end up spending way more taxpayer dollars than needed to get what is essentially an off the shelf solution.
Don’t waste time listening to anyone preach about the wonders of the 300 Blackout, literally he’s just trying to sell you something. The 9mm is just fine, and so is a 380 if that’s what you can handle best. Training and competency trump caliber selection dang near every time. Find what works for you, keep working to get better, and just ignore the people who say, “that’ll getcha killed on the street!”