Thursday, December 3, 2009

enhancing the 5.56 bullet

This is an old 2006 entry that I did for the website halfbakery. Yes, I wrote this myself so its ORIGINAL. I'll describe halfbakery in the next post.




Its an old idea about modding 5.56 bullets to make it more lethal, or rather more consistent.. How do I know this? Hey, forensics and terminal ballistics is part of the medical curriculum and I ran with it, doing my own readings on the net.
enhancing the m16/m4
[edit, delete]
deepening a cannelure to enhance the m16/m4

I. Introduction

the 5.56 bullet was derived from varmint ammunition, ammo designed for animals the size of rats and squirrels. But it was adopted for use against humans, which are much much larger animals

this is why it works against humans. all rifle bullets are long and slim with the center of gravity near the base. the spin imparted to the bullet stabilized the bullet in a point first direction. but the spin is only enough to stabilize a bullet in air. in thicker mediums like flesh the spin isnt enough and the bullet likes to yaw until the base is going first. when it is going sideways it makes a bigger hole.

All rifle bullets do this. what makes the 5.56 different is that it can fragment when it goes sideways. hold a piece of paper and stab it with someting pointed, you get a small hole. get a piece of paper and stab it while being stretched, you get a big tear. same thing with flesh. when the temporary cavity and tension of the flesh is at its biggest (when the bullet is sideways) the 5.56 fragments and the small fragments hit the tense flesh, the flesh tears, resulting in a bigger hole. The faster your bullet the more chance it can fragment, thats why the lower velocity m4 carbines do poorly at long ranges.

How come only the 5.56 fragments? because it has a cannelure. a cannelure is a notch cut in the jacket of the bullet so the lips of the cartrige case can grip it better. the notch means the jacket is thinner there and it may be weak enough to fragment.

The ak74 and the h&k mp7 and the p90 have bullets that are designed to yaw early so the biggest hole is more or less located inside your body. if it yaws too late, the bullet might have exited your body before it can yaw. but all of these dont fragment.

II. The Idea

so a problem with the m4 carbine is that the bullet is much slower than the old long barrel m16 so there is more chance that the bullet's speed will not be enough to fragment and/or the minimum range for fragmentation is much shorter. for other rifle calibers, normal FMJ ammo doesnt fragment

for the 5.56 i propose that you either deepen the cannelure or make more cuts in the jacket to weaken it. one expedient way to do it is to use a small lathe. This enhances fragementation especially for the m4. for the other calibers you can make a cannelure or else just score the bullet right above the neck of the cartrige. that way you dont have to remove the bullet from its case , just put the whole thing on a lathe and scratch a groove above the cartrige lip. I think this will increase the lethality of other rifles, especially the p90 and mp7 bullets which some critics say are underpowered.

NOTE: this might be a violation of the hague convention



Here's a link with a discussion of how rifle ammo does its stuff.

link

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