This is a diary replying to TeacherKen on the realities of modern bullets, after he posted what I consider an overly alarmist diary about bullets and wounds jumping to conclusions without I felt understanding the underlying reality. I decided my answer was getting out of hand and too technical for a comment thread, so it appears here. I'm not trying to make any statement here other than my feeling his diary was over the top, but too typical of what I see currently on DKos. I know there are Kossacks out there who understand ballistics better than I do, please feel free to comment.

Hopefully I will give you info about the why's of modern bullets. I'm trying to be as 'clinical' as possible, and I'm going to remove the emotion from the content. I hope it doesn't come off too dry.

For handguns, what was once called soft nosed bullets for most calibers are obsolete, rarely used anymore and have been replaced with hollow points. Hollow Points (HP) come in several different designs, but basically the end of the bullet has an empty cavity - an open cup that causes the bullet to deform and grow larger in diameter and shorter in length when it hits, increasing it's drag through a body and stopping the bullet inside the body. When a bullet is fired as it leaves the barrel it has all the energy it is ever going to get, and rapidly starts slowing, depending on the shape of the bullet. Hollow points are among those bullets that loose energy the fastest in flight, a point I will come back to talking about military and hunting bullets.

Full Metal Jacket bullets (FMJ), used by the military, are more like the classic lead bullet, now made with usually a copper jacket over a solid lead core. They can come in several designs from flat ended semi-wadcutters to very streamlined boattail Spitzers. All these shapes have different purposes.

Finally classic lead bullets range from a typical Lead Round Nose (LRN) to WadCutters (WC) which are just a chunk of cylindrical lead with flat ends, favored by target shooters up to about 50 yards or so.

Any of these can be deadly when used, the most important effect being not what the bullet is, but what the bullet hits. Shot placement is all important, as illustrated in a case a 20 years ago of a South Carolina State Trooper in a shootout at a traffic stop, shooting the bad guy 5 times with a .357 mag (very powerful handgun) and the bad guy lived, but the officer, wearing body armor, was shot once with a .22 caliber bullet (about as low power as it gets) which entered his body armor thorough the arm hole and he bled to death before help arrived.

Assuming all aiming to be equal, then why the different bullets? First of all, nearly every law enforcement officer uses HPs. The reason for this is two fold.

First, when a law enforcement shooting happens the officer's goal is not to kill the other person, it is to incapacitate him and make him incapable of doing further harm. A bullet leaves a gun with a certain amount of energy, all the energy it's going to get, and if a bullet enters a body, then leaves the body passing clear through it, the bullet is leaving with a lot of energy that was intended to incapacitate the target. Handguns, as firearms go, are the least powerful and that lost energy can be ill afforded when the goal is to stop someone. Most police are now taught to fire twice, then evaluate whether more bullets are needed to incapacitate before firing again. HP's usually do more damage than solid rounds, but that's physics, the energy stays in the body, and energy = damage.

The second point is what happens when a bullet doesn't stop in the body. What's behind the body? Officers are trained to look behind the body they are shooting at to try to minimize collateral damage, but realistically expecting perfect performance in a combat situation by any human being is hopeless, and bullets that have penetrated a body go flying off in unpredictable directions. However this can be helped if the bullet stays where the officer intended it. In a recent NYC shooting, five police officers fired at two suspects with FMJ bullets mandated by their department for probably the same political reasons I see you espousing, that the bullets do less damage. Well, the police fired 46 times, one of the two was killed but every bullet but one passed through him, one police bullet hitting another officer behind him and another officer getting grazed. The one bullet that killed him was the one that stayed in his body. The other suspect was shot 21 times and lived. And, three bystanders were shot also, probably from other pass through rounds.

Fiascos such as this are the reason hollow points are the logical, prudent, and although it may be a stretch to understand this, safer choice in close combat situations.

The FMJ bullet is mandated by the Geneva Convention for military use, and most amazingly that is nearly universally observed. Why would that be if the HP is such a better killer? Surely someone would cheat.

First, armies combat at ranges far in excess of police combat encounters. And they are shooting at other people hiding in or behind something, even if it's a hole in the ground. So the military round has to fly farther, penetrate barriers, and be more accurate. The HP round is poor choice on all three points.

Accuracy and power is a subject I'd like to touch on for a second. HP bullets are not designed to be accurate, and they suffer a little bit in this area. This doesn't mean the bullet goes flying off in some unknown direction when the shot, but it does mean at 100 yards distance the spread for a HP round is many times the size of a FMJ round designed for distance and accuracy. As the typical self defense and police combat distance is 7 yards, this inaccuracy is a moot point in that application. Military applications are about 300 yards.

Also, the HP round looses energy very quickly, making it undesirable beyond a few hundred yards even if the accuracy thing could be overcome. This long distance shooting is the same problem hunters face. Taking long shots they need accurate bullets more than the ability to put energy in the target,and remember bullet placement is king, so accurate for a hunter trumps all, he shoots for the heart/lungs for a clean kill, and they aren't just 'anywhere on the animal' but small targets within the body. He will use a bullet like a Boattail Spitzer, pointed at one end and tapered at the other, loosing energy very slowly in flight, and very accurate. Military snipers use similar bullets. Finally the HP is designed to crush on impact and this works against it's penetrating abilities against a barrier.

The military, asking a bullet to penetrate barriers, shoot accurately over long distances, has one other point in mind; modern military rounds are not designed to kill. They are designed to wound, which is why the military uses a round that hunters would refer to as 'varmint' caliber - suitable for something like coyotes but not for hunting say a deer. Wounding the other side encumbers them more than making dead they can easily abandon. FMJ ammo in a small caliber (5.56 Nato, which is a .22 bullet pushed to very high energies) if passing through the body and exiting, is a plus in a military situation because you may wound the guy behind him. The other reason for the military's choice of rounds is it's a far lighter round, and soldiers can carry far more ammo. In modern military actions, the side that shoots more, keeps the other guy's head down while maneuvering, wins the fight.

The last point about current military ammo, and really all 'assault weapon' ammo is that it is less powerful, sometimes by as much as half, as the rifle ammo used in WWI and WWII, and most deer hunters. That very powerful ammo was too powerful for full automatic fire weapons, and depowering the ammunition was necessary to make controllable full automatic weapons.

That said for more understanding please know any long gun shot, even with the same ammunition, usually is 60-300% more powerful than the identical round fired out of a handgun, because the bullet gathers velocity as it goes down the barrel, the more barrel the more velocity. It's just physics, energy delivered to the target is Mass X Velocity^2 and that squaring of velocity means speed of the bullet more than weight dictates how much energy is delivered to the target. Weight dictates how fast energy it shed once the bullet contacts the target which is penetration. For law enforcement, the FBI and the Border Patrol have done most of the research and determined what the ideal penetration is for a handgun round incapacitating a target. The most difficult task is designing a round that will defeat something like a car door, yet not overpenetrate a human body and exit off to who knows where. however after much testing a set of parameters were determined, and those parameters are used in designing HP bullets and selecting the calibers police officers use. The current consensus is 9mm, .40 S&W and .357 Sig weapons for most all departments, a few holding out for the old Army standard .45acp, a more slow moving but effective round with a lot of penetration, but the bullets are large and the guns have fewer of them. But in almost all cases, the bullet is a HP.

Civilians like me who carry handguns, generally carry the same calibers as the police. I am a bit of an exception, being older and remembering that the .38 special revolvers back in the day rarely had a pass through shot using LRN ammo, although most police departments now consider them woefully underpowered - the newer calibers have 50-100% more energy. I carry a 7 shot .38 spl filled with hollow points, and I'm perfectly confident it's sufficient self protection - self protection being in the 100's of encounters both police and civilian I've read about rarely goes more than 4 shots. I don't plan on initiating fire unless forced. For a civilian, if forced to fire in self defense this usually means two shots and retreat while calling 911, that's my plan anyway. This isn't the same as police encounter with intent to arrest and initiate fire if needed - I'd carry a 31 round magazine if I could if someone asked me to do that. And if I could keep from peeing my pants.

Ken, a wound is a wound, and frequently military wounds are less messy, smaller caliber and passing through in the present context. Building up drama about what and the way things are treated is pretty much artificial - worthy of the Glen Beck crowd and I think counterproductive to having a real dialog about these subjects.