Help a noobie understand critical hits

[Farmer]

Originally Posted by Colonel__Klink

Because physics lol. A 55 grain projectile 1/5th of an inch in diameter (that's what .223 refers to. "caliber" is a measurement of how wide the bore is in inches.) is not the same as a 4 lb, 4 inch wide cutting edge smashing into the rib cage. Some projectiles like the 5.56 have great kenetic energy but low momentum energy when compared (that's sort of the crushing blunt trauma effect you get from things like slings throwing heavy projectiles stopped by soft armor. )

Energy of a 5.56mm / .223 round at muzzle is about 1,650nm with a front area of about 25mm^2.

An axe (a decent sized hand axe) is about 110nm and an equivalent frontal area of an axe is harder to define, but clearly the surface area increase rapidly as it penetrates. So it has less energy and a great area, meaning the pressure is less. This changes depending on the striking strength of the wielder, of course. That's why axe rarely leave exit wounds.

Both can create lethal wounds, and if a bullet exits then not all of its energy is transferred into the target. But to say that a bullet has low momentum energy (which is a tautology) is not correct.

I think you need to reconsider your understanding of energy and how it is measured. Look at momentum and pressure in particular, but then also consider how that translates into damage of a body.