Unseen World!

There are a lot of myths and misconceptions surrounding the current M16A1, M16A2, M4, M16A4NATO 5.56 round and its effectiveness on the battlefield. Now before you make a judgment as a soldier or as a firearm enthusiast (a more euphemistic way of saying “gun nut”), consider your sources. Who is it that is telling you the 5.56mm, or .223 if you prefer, is an ineffective round? Is this source an armchair general who has watched Blackhawk Down one too many times; or a Navy Corpsman who has been attached to a MEF fighting in Fallujah and has seen, treated and inflicted these wounds with his own M-4? People look at the .30-06 round from their grandfather’s M1 Garand and the 7.62×51mm round from their dad’s M-14 and compare it to the M-16/M-4’s 5.56 and think; “Wow, this is considerably smaller. Therefore, it must be less effective.”

M16A1, M16A2, M4, M16A4

Now Joe Nichols had it right when he said, “Size Matters.” However, when you are talking about combat cartridges this is not always the case, and I say that hesitantly. When the 5.56 was derived from Remington’s .223 in the late 1950’s, it was meant as a “force multiplier” if you will. By that I mean a soldier could literally carry twice as much ammunition as one who has the older 7.62 for the same weight. They wanted a soldier who could stay longer in the field without re-supply and could literally out-last and out-shoot the enemy in many aspects. The 5.56 is an incredibly fast and flat shooting round compared to the 7.62, but is under half the bullet weight.

So one might ask; ‘How in the world can a smaller bullet be more lethal than a bigger one?” One word: cavitation. Cavitation is the rapid formation and collapse of a substance or material after an object enters it at a relatively high velocity. I guarantee you have seen cavitation before. Next time you are in the pool or on the boat, look at your hand as it passes through the water or the propeller spinning. In both cases you will notice bubbles on the trailing edge of each. You see this because the liquid water falls below its vapor pressure. Without getting into physics and the hydrodynamics behind it, I’ll just leave it at that. When a human body is hit with a 5.56mm 62-grain bullet traveling at 3,100 feet per second; essentially the same thing happens but much, much more violently. For a split second, the cavity created inside the human body by the round from an M-16/M-4 is about the size of a basketball (if hit dead center of mass). The 5.56 creates this massive cavitation by tumbling through the body initiated by inherently unstable flight.

5.56 ballistic test

(continue reading…)