Knockdown Power

[gsparesa]

So, I should be using a bat on the perp instead of my 629?

[Distro]

If catching an 80mph "fastball" feels like the recoil of a handgun then that truly is limp wristing.

[hundreddollarman]

Next time someone talks about "this caliber is better than that one blah blah blah," maybe they should get shot in the knees and tell us which one hurts more. Just my thinking.

[Sheepdog1968]

People have died from 22's. People have lived from shotgun slugs. All bets are off. The most important thing is to be able to hit your target under stressfull conditions all the time. That takes lots of practice. Find a caliber you like (ideally somewhere along the 38, 357, 9 mm, 10 mm, 40, 45 caliber lines) and practice a lot. Other than that, I tend not to worry about all the formulas to calculate what is best as you will never arrive at a single answer or enlightenment.

[Cato]

There's no such thing as "knock down" power from guns. Bullets are TINY. When they hit it's similar to getting stabbed with an icepick. Your goal should be to "stab" a vital organ, not "run" someone over with a Mack truck.

[JMP]

This topic comes around now and then and I've read several threads, but I just thought of a new way to think about it that makes sense.

I've read enough threads and done some calculations, to say that a 45 acp has knockdown power similar to an 80 mph fastball... which isn't that much "knockdown power". Knockdown power is generally a myth.

The new way to think about it though is "for every action, there is an equal and opposite reaction". If you fire a weapon that knocks you back on your butt, then yes, that probably has some real "knockdown power". But that's going to be something like an elephant gun, that is hard to manhandle the kickback.

Just thought I'd share. Knockdown power makes more sense to me thinking about it that way. Cheers!

dafuq--can you show us your calculations? How did you arrive at this conclusion. The 80 mph's angular momentum and rotational inertia may vary significantly if the pitcher's has a cross-seam or with-seam grip.

[AeroEngi]

Actually, if you're looking at it from a momentum standpoint (recoil = momentum = knockdown power), a 230gr projectile with velocity of 850 ft/s is more like a baseball with a velocity of 61 mph.

The average baseball weighs around 142 grams which converts to about 2,187 grains. 61 mph converts to 89.47 ft/s. Multiply them together and you get 195,643 grains*ft/s.

For the bullet, a 230 gr projectile at 850 ft/s gives you a momentum of 195,500 grains*ft/s.

[AeroEngi]

Don't know why it double posted.

[vliberatore]

Hmm..and I've caught 80mph with my bare hands...

Who wants to come over so we can try .45 ACP?

[mjmagee67]

Shot placement, shot placement, shot placement!

[SJgunguy24]

Bullets kill one of 3 ways, shock, trauma, and blood loss. They all do the same thing. People get hit with handguns and run or keep fighting. Unless you hit the pump center, nerve center, or shatter a weight bearing bone, your still in a fight.
The biggest difference with rifles is the amount of damage done do to velocity and bullet design. There is no knock down power with handguns.
Google Jennifer Fulford-Salvano, she took 10 handgun rounds, 3 were stopped by her body armor. That's 7 hits and she kept fighting and killed 2 men.

[Marthor]

Actually, if you're looking at it from a momentum standpoint (recoil = momentum = knockdown power), a 230gr projectile with velocity of 850 ft/s is more like a baseball with a velocity of 61 mph.

The average baseball weighs around 142 grams which converts to about 2,187 grains. 61 mph converts to 89.47 ft/s. Multiply them together and you get 195,643 grains*ft/s.

For the bullet, a 230 gr projectile at 850 ft/s gives you a momentum of 195,500 grains*ft/s.

When I did the calculation over a year ago, I was probably calculating that at most it's like an 80mph fastball.

Using upper end 230 45acp +P can go 1134 fps at close range.

Do a replace ratio on your calculation...

61 mph X (1134/850 fps) = 81 mph

You can find 45 ACP in a wide range of velocities.
850 fps is on the lower end on cheap target ammo.

[AeroEngi]

When I did the calculation over a year ago, I was probably calculating that at most it's like an 80mph fastball.

Using upper end 230 45acp +P can go 1134 fps at close range.

Do a replace ratio on your calculation...

61 mph X (1134/850 fps) = 81 mph

You can find 45 ACP in a wide range of velocities.
850 fps is on the lower end on cheap target ammo.

Oh nice! I didn't even think about that. I was just using numbers for standard 230 gr .45 acp. Either way, knockdown power is pretty insignificant.

Sent from my DROID RAZR using Tapatalk 2

[AeroEngi]

Don't waste your time trying explain to people on here basic known scientific facts like Newton's laws. They have it firmly set in their minds from watching Hollywood TV shows & movies, that .40 and up pistol rounds posses tremendous knock down power. Powerful enough to lift you off your feet & throw you backwards. Enough power to toss around a 250lb person, yet can somehow be easily fired with one hand. They also wrongly believe that hollow point rounds enhance knock down power.

In the real world you can watch Richard Davis get shot with pistols, shotguns & rifles multiple time while wearing his 2nd chance vests, even while standing on one foot & not get thrown to the ground. The movie to watch with those scenes is called: Deadly Weapons: Firearms & Firepower from 1985.

Actually, hollow points could enhance knockdown power. A hollow point will transfer most if not all of it's momentum into it's target. A standard round nose projectile will likely exit it's target out the back and not transfer all it's momentum into the target.

[Marthor]

http://www.youtube.com/watch?v=ged4lz_Fw2Y&feature=youtube_gdata_player

Check out the video. You have to go up to a huge caliber rifle (elephant gun) before you get some good "knockdown power".