{"id":1861,"date":"2012-07-09T23:40:13","date_gmt":"2012-07-10T03:40:13","guid":{"rendered":"http:\/\/nimlas.org\/blog\/?p=1861"},"modified":"2012-07-10T00:06:55","modified_gmt":"2012-07-10T04:06:55","slug":"part-4-of-a-ballistics-guide-for-geeks-writers-and-geeky-writers-terminal-ballistics","status":"publish","type":"post","link":"https:\/\/nimlas.org\/blog\/general\/part-4-of-a-ballistics-guide-for-geeks-writers-and-geeky-writers-terminal-ballistics\/","title":{"rendered":"Part 4 of A Ballistics Guide for Geeks, Writers and Geeky Writers: Terminal Ballistics"},"content":{"rendered":"
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A Fired .38 caibre Hollow Point round, completely expanded and deformed after striking its target. From Wikipedia, by user Rickochet<\/p><\/div>\n

Welcome back! So far we’ve talked about the flight of projectiles, and how things change as our projectiles and the atmosphere around them change.\u00a0 Now lets talk about what happens to our projectiles when they actually impact with something!<\/p>\n

These projectiles that we’ve thrown have now flown from their projector to the other end of their ballistic trajectory.\u00a0 Eventually, they’ll hit something other than the medium they are flying in.\u00a0 Wether it’s the intended target, something that happens to be in the way, or one of those weird bubblegum asteroids those Sci-Fi writers keep dreaming up, something will happen.<\/p>\n

So what happens?\u00a0 Well, I guess in the simplest explanation, Physics happens.\u00a0 As I wrote that, I realized it was wrong because physics didn’t just happen.\u00a0 It’s been happening the whole time.\u00a0 There are many factors and many different types of projectile we could be discussing, and I may delve into some of those later, but for now, let’s stick to simple bullets, and what happens when they strike human (or human-like) targets.<\/p>\n

The instant the bullet leaves the barrel, it has been imparted with all of the Kinetic energy it’s going to get from the gun.\u00a0 That is of course, unless it’s a self-propelled projectile like a rocket or missile.\u00a0 That kinetic energy imparted gets slowly bled off by aerodynamic (or hydrodynamic, or bubblegum-dynamic all depending on the chosen medium of travel of course) drag until the projectile impacts its target.\u00a0 The remaining kinetic energy then gets transferred to the target.<\/p>\n

What occurs during that transfer is based on the interaction between the target and the projectile.\u00a0 If the projectile has enough density and kinetic energy, it will pass through the target.\u00a0 If the target has enough density and mass, it will stop the projectile.\u00a0 Either one could be the intended result, depending on the design of the projectile. In modern military small arms ammunition, this is generally divided into two broad categories:<\/p>\n

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Full Metal Jacket ammunition, from Wikipedia, by user Major Tom<\/p><\/div>\n

Full Metal Jacket (FMJ) ammunition has a dense lead core surrounded by a harder metal jacket, usually copper.\u00a0 This shell prevents the bullet from deforming as it transfers its kinetic energy, allowing it to retain more energy as it travels through the target, hopefully emerging on the other side.\u00a0 By the laws of armed conflict, several Geneva Conventions and other agreements this is the type of ammunition most civilized nations use in their military small arms.\u00a0 The reasoning is two-fold.\u00a0 A through and through wound is easier to patch up.\u00a0 There is less risk of fragment contamination, it makes a smaller wound tract, and the target has a higher chance of survival.\u00a0 Also, if the target is killed outright, they are taken out of the fight.\u00a0 If the target is wounded, it takes two other people to carry them out of the fight.\u00a0 One bullet just removed three people from the conflict.\u00a0 We can all see the realistic problems with this idealistic view of a battlefield, but that is a discussion for another time.<\/p>\n

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Jacketed Hollow point ammunition, from Wikipedia, by user OlegVolk<\/p><\/div>\n

Hollow point (JHP): or soft point ammunition is designed using a mix of a dense inner core, a harder outer jacket, and some sort of soft plastic (usually) tip or hollow space at the nose of the bullet.\u00a0 When this type of ammo strikes a dense enough medium, they immediately begin to deform during the transfer of kinetic energy.\u00a0 This deformation usually takes place in the form of some sort of expansion, increasing the surface area of the bullet against the target, increasing the rate of kinetic energy transfer.\u00a0 This type of bullet leaves wounds typically seen, as short, massive wound channels with the bullet still in the wound.\u00a0 This has several advantages, the first and foremost being the higher chance of a one shot incapacitation.\u00a0 Of course, if the shot is a graze, or impacts in a non life threatening area, the wounds tend to be much more severe than with a full metal jacket round.\u00a0 Police and Hunting ammunition are normally of this type.\u00a0 Police services like to use it as it helps guarantee a quicker incapacitation of a target if they have to take a shot at someone.\u00a0 Also, because of its tendency to quickly deform and transfer kinetic energy it has a lower chance of over penetration into say, someone else or into the next room through the wall.\u00a0 Hunters use deforming ammunition to help guarantee a first shot kill by creating as powerful an impact as possible in their chosen calibre.\u00a0 Hunters are also usually forced to choose this type as most jurisdictions have outlawed full metal jacket ammo to reduce the instances of wounded prey animals running through the woods with through and through gunshot wounds.<\/p>\n

And now a visual comparison of the Terminal effect of these two types of ammunition, fired at Melons.\u00a0 From Youtube user TrainASDI:<\/p>\n