Body armor does not qualify as "soft targets". unarmored personnel are soft targets.

Had a downchecked Kevlar Vest lying around this summer. Grabbed several guns. .22lr, .38, .357, 9x19mm, 10mm, .45ACP, 7mm mauser(High powered rifle, .27ish), 7.62x54 (high powered rifle .30cal), .223 (high powered rifle very small caliber, about the same as 5.56 Nato)

Proceeded to shoot the living crap out of the vest.

Not one round penetrated fully.

Edit: No these weren't "AP" rounds. They were a mix of soft-point, FMJ round-nose, FMJ spear-point and JHP

Back to context
a man in military grade combat armor in 2010 (much less 2072), would not be considered a "soft target" if included in a survey of battlefield wounds in Vietnam.

One thing I have often wondered about high velocity projectiles is whether or not body armour actually does more harm than good.

I remember reading a study of gun-shot wounds in Korea and Vietnam which suggested that very high energy rounds that did not pass through vital organs did relatively little damage because they did not start to tumble until after exiting the target. Slower projectiles that started to tumble immediately caused massive exit wounds and the corridor of damaged internal tissue was substantially larger.

It has made me suspect that high calibre rounds that penetrate body armour will have slowed enough to start tumbling inside the target when they otherwise would not have, thus substantially increasing the damage the target suffers rather than decreasing it.

A boxer's strongest punch transfers about 300 Joules of force.
A .50 BMG round delivers around 15,000 to 20,000 joules of force on on target.

I too remember reading a study that seemed to show that you had more severe injuries from GSW when you were wearing a flack vest (which won't stop bullets) in Vietnam than when you were not. It was based on detailed USMC records IIRC, but I've been unable to find it again.

That's why .45 ACP is the holy and sacred all-American handgun cartridge. Wide diameter + low velocity = win. Smaller diameter + higher velocity = fail.

That's why .45 ACP is the holy and sacred all-American handgun cartridge. Wide diameter + low velocity = win. Smaller diameter + higher velocity = fail.

So a tennis ball is more lethal than a 5.56mm round? I beg to differ (IMG:style_emoticons/default/biggrin.gif)

Depends, a tennis ball with 1.5kJ of velocity might sting.

How much mass does a tennis ball have?

Uhm, I assume you meant "enough velocity for 1.5kJ of kinetic energy" (IMG:style_emoticons/default/wink.gif)

A golf ball with the energy of 5.56 NATO has a velocity of 608 mph.....

Velocity is energy

A golf ball doing over 500mph is going to hurt like hell. I imagine it might even penetrate an un-armoured person.

edit

A golf ball with the energy of 5.56 NATO has a velocity of 608 mph.....

And at relativistic speeds even a cotton ball will make targets simply explode...

And at relativistic speeds even a cotton ball will make targets simply explode...

Depends on the size of your target.

A little math reveals that a 5,000,000,000,000-tonne asteroid traveling at 90% of light speed would be sufficient to destroy Earth (causing a big enough explosion that the resulting rubble never recoalesces back into a planet).

In the spirit of the OP perhaps I should insist that you fire two of those.....

Your original premise was comparing Tennis balls to bullets.

My original premise was that "wide diameter and low velocity beats smaller diameter and higher velocity at similar kinetic energies" is too simplyfied, as it becomes evident when comparing a tennis ball and a 5.56 bullet at their normal speeds.

Unless your you're military. Then we use .22s in our rifles and 9mm handguns. We're not actually trying to kill them.

Back of my hand guess is that that would make heads explode.

as to 45acp, wasnt there a study done after the philipine war that concluded a 45 caliber pistol bullet is the smallest caliber of ball ammo that will usually take down its target in one shot?