Thursday, December 20, 2007

Gun Myths: Part 1

If you read gun boards, you inevitably run across the same garbage over an over again. Here are two I saw today:

Myth 1: The amount of energy a bullet has is the most important thing in it's terminal ballistics.

Truth be told, bullets don't have that much energy. If you took all the kinetic energy from a bullet fired from my AR-15 and used it to heat a standard 8oz cup of coffee, you'd raise the coffee's temperature by a couple of degrees Fahrenheit. That's it, just a couple of degrees. And handgun bullets are much less powerful than rifle rounds.

This is important because humans are a lot like a cup of coffee. We're mostly water with some extra organic compounds. Bullets really don't have that much energy compared to what our body can absorb. So it isn't the amount of energy that matters, it is how that energy gets used. You want a bullet that is good at breaking stuff and the right stuff. You want a bullet that will penetrate deeply to the very important parts of the human body like the heart, lungs, and central nervous system. The parts that are buried deeply because it makes them difficult to injure. Then you want it to damage those critical parts when it gets there.

Now more energy is good because tends to help you put the hurt on. But "tends" is a key word because it doesn't have to do that. You really need to look at expected penetration and expansion rather than some energy number. Why? Because manufacturers like to sell ammo by putting up big energy numbers. They do this by using very light bullets that won't penetrate as well as a slower, less energetic round will. The light bullet just doesn't have the mass to provide adequate penetration.

Myth 2: Caseless firearms don't need extraction systems.

Caseless ammunition is ammunition that does not have a traditional brass cartridge. It uses a different technology so that, if everything goes well, the case is either consumed in firing or sent out the barrel with the bullet. The closest caseless ammunition has been to fielding is the G11 rifle the Germans were working on when the Cold War ended. Caseless has its problems, like ammo durability and heat transfer issues. One of it's reported strengths is that it simplified gun design because you not longer need to extract the case. This is largely BS. Why? Because there are lots of reasons people want to get a bullet out the chamber of a rifle.
  • If the gun fails to fire, the standard clearance drill is the Tap, Rack, Bang drill. You tap the magazine to make sure it is seated properly, rack the bolt to get a new round in the chamber from that magazine, and fire the gun. If you don't have a manual extraction system on the gun, you can't do the rack step so it won't clear several kind of problems. This is something that needs to be done easily in combat.
  • Standard procedures for making firearms safe and storing them generally require an empty chamber on the gun. How do you do that without an extractor of some sort? This is something that is performed routinely and ought to be accomplished easily.
So you need at least a manual extraction system even for caseless guns. Once you have a streamlined manual system, making it automatic isn't hard. You just make sure recoil or gas pressure exerts similar forces in similar places that the rifleman's hand does.

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