[masraum]

Originally Posted by beatnavy

High velocity / lower mass rounds tend to expend their energy inside the target instead of just going in one side and out the other. It's a lot harder to survive something that tumbles around inside the body rather than simply blowing through. A regular ol' .22 that's not high velocity doesn't apply here.

Someone correct me here on the physics, but I believe momentum = mass x velocity. Momentum is what keeps something going in the same direction, as in straight through the target.

Kinetic energy = mass x velocity (squared). So higher velocity has a lot more energy, and the lower mass means it won't necessary keep going in the same direction. It expends its energy inside the target rather than going through and out the other side.

It's the same reasoning told in the old story (true or not) about why the US military switched over to the 5.56mm round of the M16 right after convincing NATO to go with the 7.62mm back in the 60's.

At least I believe that is the theory / story.

I wasn't able to find the clip, but the mythbusters once did a test where they fired guns down into a swimming pool. I think they started with something like a 38spl or 9mm, and worked their way up to a 50cal out of a rifle.

I wasn't able to find the entire clip, because I'm pretty sure that they tested multiple types and calibers of guns, but I think the determination was that you were pretty safe as long as you were a few/several feet underwater.