Some friends have been debating an article about the differences between .45 ACP and 9mm for military secondary (pistol). The effectiveness in the real world has caused issues and a lot of expensive debate. The 9x19mm Luger is the NATO standard pistol and SMG round. It will not penetrate body armor, and is mostly annoying rather than deadly to armored soldiers. It does work out to about 70 yards. The .45 ACP dates back to 1911, and was designed to essentially duplicate the .45 Peacemaker with the latest powder and velocity at the time. The trouble is, the case is over 100 years old, and is only able to hold lower pressures, around 15,000 PSI. Compare that to 50,000 PSI for a basic rifle round. The .45 is usually 770 feet per second (FPS), just below the speed of sound. The 9mm is around 1150 feet per second, on average. This difference in velocity also affects the effective range of the rounds. A .45 requires special sights to hit things beyond 25 yards. While most crime-based gunfights occur at 7 yards or less, and is over in 4 rounds.
The 9mm effectively duplicates the power of the .357 Magnum and .38 Special, though the magnum can deliver a heavier bullet at higher velocity, though this can lead to the bullet blowing through an unarmored target, hitting things or people beyond. This has been a problem, called "blow through" for police for some time. The police, deputies in particular, prefer the .357 to any other round because it will kill at 100 yards, and tear through armor, some of the time, and hit hard enough to break ribs or stop a heart from the kinetic energy transferred through the impact. Armor stops it going through you, but the energy still pokes very hard.
And while I'm sure you're aware, the .44 Magnum is really powerful. About twice the energy of a .45 ACP. And that provides really painful recoil, requiring someone big with solid shooting technique and a lot of practice. The big round launches from a full sized revolver around 1800 fps with a 7 inch barrel, which is bare minimum for the round to make any sense. They do make carbine rifles, the old Western lever action Winchester (18)94 will fire it. Few people like it for that rifle, however, and as bad ass as that sounds, at 100 yards, the much softer shooting .30-30 hits harder. Why? Because bullets lose velocity very quickly. They have DRAG, so the muzzle velocity bleeds off faster the bigger the round is in diameter. Rifle bullets are much longer, less wide, which is why the 45-70 has only a couple hundred yards of range and drops to the ground fast. Same with the AK-47. Its a short bullet, sent fast but slows down fast and is pretty worthless beyond 200 yards. The .223/5.56 NATO is a longer bullet, sent faster, and produces considerably less recoil than the .44 Magnum, and again, hits harder at 100 yards. This requires a longer barrel than the .44 revolver, or it doesn't work.
Attempts have been made to shorten the M16 for use in urban environments. They also started using longer 80 grain bullets able to punch through body armor more reliably than the original 55 grain from Vietnam, and the later improved 62 grain we used in Desert Storm. The trouble with the 80 grain is in a shorter barrel, there's less distance to accelerate so the muzzle velocity is much lower. And since the .223 only works right FASTER than 2000 FPS, and the shorter M4 muzzle velocity with the 80 grain bullet is only 2100 fps, and the bullet loses energy the instant it leaves the muzzle, its actual EFFECTIVE range is 8 yards. Do you see how pointless that is?
The discovery that the 80 grain bullets were worthless in the rifles soldiers carry in Iraq and Afghanistan caused a lot of grief, and preventable deaths, in the military. The 6x45mm (a .223 necked up to 6 mm) holds more energy downrange and accelerates faster due to the larger diameter barrel. The 6x45 is a dandy round for poaching small game in Africa, which is what its really used for. A bush meat rifle. We don't use them here, but we should. They do two different bullet loads. The 85 grain supersonic for flat reach. And 100 grain subsonic for closer range hunting. At the low velocity the bullet doesn't break up so you can eat more of the meat. Considering the size of the deer here that would work just fine. The big advantage of the 6x45 is it fits the eponymous STANAG NATO magazine and the existing receiver and bolt carrier of the AR-15. You have to change the barrel, obviously but its a pretty simple conversion otherwise. Of course, NATO won't do that since they have so many trillion rounds of .223 in storage. And if you have to change to a more effective rifle round, why insist that your magazines define your choices?
Well, a special forces project actually DID that. They took the updated .30 Winchester, the high pressure version of the .30-30, rimless and able to take 55,000 PSI pressures in the case. That's typical modern rifle. They experimented with .223, 6mm, 25 caliber, 270, 7mm, and 308. The best choice compromise was the 270 with a light 117 grain bullet. They found this will kill at 600 yards, fits the STANAG magazine with an easy modification to two parts, and holds 26 rounds in the standard 30-round .223 magazine. This is an improvement over the .223 and is an easier fix for the M4 than trying to upgrade the entire armory to .308 caliber rifles, then training men used to spray and pray to pick their shots because you just can't hit if you spray a 20 round magazine of .308. Too much recoil. They call this compromise 6.8 SPC. Its not perfect. Its a compromise. Its only useful in hunting at pretty close range, against light game. It won't take elk, for example. The round is too light to penetrate very far. Good for feral pigs though. And deer at closer range.
I'm kinda surprised they didn't do any work on the 270 ARM. That is a 308 necked down to fit a .270 bullet. With modern loads, this gets you a 270 Winchester's range and power and bullet weights but fits into an AR-10 or other .308 caliber rifle rebarreled to sit the .277 bullet. Unlike the 6.8 SPC which can only work with the 117 grain bullet, the .270 ARM will shoot standard 120, 130 and 140 grain bullets. Including hunting bullets, and has the reach to take game out to 400 yards. And military targets to around 800 yards. It also fits into a .308 rifle's magazine and mechanism.
The other advantage of the .270 is there are a couple different magnum rounds which in a bolt action precision (sniper) rifle gets you 1000 yards of potentially accurate fire. This becomes a survival round, a hunting round, and precision round. The 270 WSM and Weatherby Magnum are well known and even available commercially. A reasonably well trained rifle marksman wouldn't be disappointed with the long range reach of a .270 Magnum. Or go to higher calibers, like the .300 Winchester Magnum, and the .338 Lapua Magnum, favored by serious snipers making up to 2 mile shots.
Still, this is beyond the scope of a pistol for the army to carry. The SOCOM guys like the .45 ACP because it drops targets close enough to be hit by them. So why isn't there a faster version in a stronger cartridge case? Yes, you can overpressure a 45 ACP in the +P+ version, and if you use strong enough springs and reinforced parts to prevent the thing blowing itself apart. This is NOT a joke and that's a relevant set of concerns. There's also .45 Super, but its a same size as the ACP and is similar to a +P+ in power. This isn't quite good enough if you want a flatter shooting round able to reach like a 9mm.
Compromises to fit into a 1911 frame include the 10mm and the 9x23. The 10mm was designed by Jeff Cooper to duplicate the power of a .44 Magnum in an automatic, which can be fed by magazine. It is for serious urban combat. This round has been chambered, briefly, in the H&K MP5. You can also get it in a M4, though the magazines are finicky. The big problem with the 10mm is its a special case, and the ammo is expensive. The short version of 10mm is 40 S&W. That one is getting pretty common since it fits into a 9mm sized frame, but it loses a lot of the advantages of the 10 mm. It does have the range of the 9mm, and more energy due to its mass being higher. And it puts a hole that's a whole millimeter bigger. But in a personal defense pistol and in use with carbines? You really should have the 10 mm for combat. And for police. And for self defense in Black Bear Country.
In case you wondered, the Grendel P90 shoots a proprietary .221 Fireball, which is really a slower .223 with a much lighter bullet, able to fire with a blowback action which is really cheap to make compared to the locking AR-15. The gun it is cheap, the effectiveness is limited, and the ammunition costs whatever FN decides to charge for it. Its a huge markup, in case you wondered. The Grendel is meant to be a counter-terrorism armor piercing urban attack gun. The rounds are light, bleeding off energy very fast and stop punching through walls not too far away. The M4 would work, as it is, if you lowered the projectile weight back to 55 grains. Nobody wants to do that.
So yeah, the 9mm isn't quite big enough to affect armored targets. The .40 S&W isn't much better. The .45 ACP doesn't have the range. The 10mm has the range and the hitting power. A faster 45 would too. I think they should focus on that.
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