Someone to do the math

[lefty o]

not scientific, but ive seen 22lr bullets completely penetrate 1/2" plywood at over 500yds. now my guess is at that distance projectile velocity is getting pretty slow. now to my point, if it will penetrate 1/2" plywood, it would more than likely be able to pierce a skull thereby being able to cause deadly injuries. like i said, not scientific by any means, but i believe the reasoning is fairly sound.

[rfc357]

I don't have my ballistics software available right now, but calculations I did yesterday showed the .22 is still moving at 600 fps at 1000 yards. Penetrate plywood at 500 yards? Sure. And if it can penetrate plywood, I don't want it hitting me!

[BPierce]

I found this on another forum. The author is a respected member of the forum but I don't know if anyone has checked his math
From: "Popgunner" thefirearmsforum.com
A .22 cal 50 grain bullet fired straight up from a .222 will stop at 9,000 feet elevation & accelerate downward at 32 fps from the first second, 32 fps faster during each of the second & third seconds. Then air resistance starts building & the fourth second it accelerates only 26 fps. It attains "terminal velocity" a few seconds later at 290 fps & 9 ft lbs of energy. This is assuming it's dropping point first. A .30 cal 30/06 bullet would fall at 300 fps terminal vel & have 30 ft lbs of energy.
Military standards for producing a lethal wound are 58 ft lbs of energy, but I wouldn't want to be hit in the head with a 150 grainer at 300 fps.
More likely, the bullets would fall base down & still be spinning.
I've been "peppered" by shotgun pellets a few times & it's never even stung that I can remember.
Also; he is talking about a .222 bullet not a .22 LR/RF. The RF bullet is closer to a sphere in shape and might not oscillate as much as the .222. Mithbusters did a segment in which they calculated the speed of a 30 cal. bullet falling to earth (this speed was highly dependent on the bullet falling base first and oscillating, although they always did.) They fired a bullet at a pig head at that speed and it bounced off. They also did actual tests with the bullets falling in sand and this supported the lab results.

[BattleRifleG3]

That's some great info. Here's an engineering take on it:

Military standard for lethal wound is 58 ft-lb of KE. That's from the perspective of someone trying to kill, not someone trying to keep people safe. So take that far down when considering safety. A 22LR has roughly 1/6th that energy. While that looks small, it's not as though it's different on an order of magnitude. And if you're thinking about non-22s, having more than half of a military's minimum killing power is pretty significant.

Next, KE is one element to measure ballistically. It's not the only one. It's equal to the mass x velocity^2 / 2. So KE favors velocity over mass. KE is best related to penetration of hard targets that undergo plastic deformation. Biological matter absorbs energy into fluid displacement, elastic deformation, and britile fracture, but not much plastic deformation. In the case of bullets not being lethal I'm not sure how this would apply. Usually heavier bullets at more modest speeds are more destructive on tougher game.

Here's probably the only way to make sense of that data. Picture a 22 LR bullet in your hand. Imagine throwing it as fast as you could. Now imagine the fastest pitcher in the world throwing it. Would you want to be in its way? No, though you may not fear for your life either. But picture 290 feet. Now imagine a bullet flying so fast it covered that distance in one second. Do you think you could stand in front of it without risking possibly fatal injury?

[GoodAim]

I would like to add one important piece of info for this topic. You can do serious damage with only 9 ft-lbs of force at 290 fps. I has alot to do with the actual size of the round. It's easier to push a pin through something than say a eraser end of a pencil. So It takes less applied force to make a .22 penetrate than say a .40 cal. You have to keep that in mind.