Help with an Argument on "knock down" power

My two buddies came home from Paris Island Boot Camp in 1968, advising that the reason the 5.56 was so effective was that it starting tumbling out the barrel.
Click to expand...

I got really tired of hearing that one too. You would think that an ordinarily intelligent person could look at thousands of bullet holes on paper during boot camp and other training and still believe that the bullets were flying Willy nilly, tumbling through space like every football pass I ever made.
 
Ed matunis created a scale called the martinis power level that wasn't even an attempt to be scientific, but it was logical and probably pretty accurate. His equation included

Bore diameter
Weight
Velocity
Bullet construction

You wound up with a ke (momentum) number, factors sectional density, then increased it according to bullet shape and function, and the resulting number gave an approximation of how well a round would hurt someone

In this order, he used bigger, heavier, faster, and round, that, or expanding. His numbers said that a Lrn .38 wouldn't work as well as a flat point .45 at the same velocity. I believe that he was right on that count.

His idea that bullet selection should be part of any assessments took thirty years, but right now, it is close to the single most important factor in choosing hunting or defense ammo. The fbi thinks so, as do nearly all other educated people. If you ask them to give up their hollow points, unless some unusual problem exists, they will decline.
 
Smaller 30 caliber bullets need to use the hollow point trick or soft point expansion to be more effective. 45+ big bore calibers don't need that, just a nice wide meplat to get the job done. Pretty basic but a good rule of thumb.
 
The high velocity rifle used to be available in hunting hollow points, they were exactly like a standard modern soft point, but they bab no exposed lead, a small empty space behind the gameplay, and a tightly closed tip on the jacket. These were pretty much identical to varmint hollow points, but built heavier for big game. Exposed lead contributed to quicker start to expansion and more reliable expansion, so most big game bullets, cup and core, non tipped, etc, are made with some exposed lead.

I have a specimen of a Winchester .270 with that hollow point.
 
"He says "Ahh, Newton’s third law…it doesn’t apply as you imply. If the bullet stopped at the muzzle with no means of continuing forward or projecting that force forward, the reciprocal force might cause the shooter to be knocked down. But, since the forward force is continuous and dissipated along the trajectory of flight (and the backward force is mitigated by recoil controlling design) said knocking down of the shooter only happens occasionally."

I talked to Newton (Issaic AND Fig).

They both say "YOU KNOW NOTHING OF ME OR MY WORK, SIR!"
 
"Enough with the Newton’s Law crap! When used as an argument it sounds good, and apparently is very popular, but it does NOT work as you suggest. As I said before, that is simply throwing out a fine sounding physics term, but not doing the calculation!
Click to expand...

Ah, yes, the college boys have all those fancy sounding words, but I've got my unshakable beliefs in the gnomes, pixies and fairies.
 
Tennessee Gentleman wrote:
An old Army buddy and I are arguing about the phenomenon called "knock down power" [edited to add quotes]
Click to expand...

Before we go any further, how do you and your buddy define the term "knock down power" and how do you propose to quantify and measure it? From what follows your original post in the thread, it seems as if you are equating it to momentum (mass times velocity) and that's a poor proxy as it fails to take into account the many masses that are involved, what velocities are being imparted to them, the time over which this is occurring and the higher order derivatives of velocity such as acceleration and jerk that apply.

Can a bullet knock somebody down.
-- Certainly.
----- I've seen it happen.
--------It has actually happened to me.

Can the recoil of a gun knock someone down.
-- Again, certainly.
----- I've seen it happen.

Does it always do that? Of course not. People aren't blown around the firing range like so many autumn leaves by the recoil of their guns. The discovery of the mechanisms at work to explain why some people get knocked down and others don't and how you would quantify and measure what's going on would be the start of any discussion of "knock down power".

Until you and your buddy define the term, further discussion or analysis of an undefined term using an inapplicable metric is pointless.

Within the last year on TheHighRoad.org, one of the members posted the entire publication history of the International Wound Ballistics Association's Wound Ballistics Review. It's still available and makes for fascinating reading and a thorough study of it would be particularly useful for this conversation as it would provide a practical basis for formulating the concept of "knock down power".
 
briandg wrote:
Momentum cannot ever possibly be entirely transferred from one physical thing to another, elastic or inelastic, because in EVERY collision there is energy converted from momentum into some other form suck as heat.
Click to expand...

The OP and his buddy are stuck trying to use conservation or momentum from Newtonian physics with a questionable frame of reference without identifying all the masses and velocities involved and you want to bring the 2nd Law of Thermodynamics into consideration?

That's brave.
 
It's hard for me to understand. One can only try. If a person talks about energy being transferred and converted to movement, in particular the vibration of a going hit by a bullet, with the going vibrating, the energy of the vibrations being transferred to whatever medium is available, such as air, those vibrations that shake the air are perceived as sound.

There is now the question of

"Since you can't hear anything in outer space, where does that energy go?" If someone hits a gong and they are wearing really good ear muffs, did it really make a sound?

I'm going on 30 hours without sleep and this is making my brain hurt.
 
hdwhit said:
Before we go any further, how do you and your buddy define the term "knock down power" and how do you propose to quantify and measure it?
Click to expand...

Here is my definition I proposed to him earlier. An average sized male standing upright, sober and conscious, is knocked off his feet to the ground purely by the force of the handgun bullet strike. This is not to be confused with "falling down" due to psychological or physiological means.

The FBI says such force would also knock down the shooter due to Newton's third law. The FBI further says that "stopping power" is a myth and the effectiveness of a round should be measured by wounding or medical reasons.
 
You are right, t.v., I also agree with your definition. Knock down means, literally, knocked down like a bowling pin. fall down is completely different. Man stopped is ridiculous, nothing short of electrocution will ensure that he is 'stopped'. The fbi and other sources refer to an 'ouch' factor. How seriously the round will injure a man at several levels of impact. Will the guy swear loudly and keep on fighting, or will he look down, see his liver laying on the ground and faint? I'd like to have ammunition that will probably shred a lot of the things that keep him alive. I'd like to have it for fifty cents a round, and able to fit into a pocket pistol.

A lot of people believe that such around exists, but the government has banned it.
 
The idea of the shooter being knocked down is made even more ridiculous by the fact that just the mass of the gun is enough to minimise the recoil f lots of rounds.
 
If it isn't the bullet, then, what is it??

Seriously, if it isn't the size, weight, speed, momentum, or any other factor of the bullet (no matter which formulae are used), then what is it that "knocks" them down??

Perhaps the myth is the idea that it is the bullet that knocks down a live target.
 
Perhaps the myth is the idea that it is the bullet that knocks down a live target.
Click to expand...

Well, yeah, that's been said. No bullet "knocks down" any living target.

Causing that target to fall isn't the same thing, right?
 
Wikipedia entry on tko

The TKOF has no physical meaning or scientific basis and is strictly used as a figure of merit for comparing cartridges. Its main advantage is the ability to attempt to represent complex terminal ballistics as a number. This can be utilized to assign different wounding capabilities to projectiles in video games.
Click to expand...

Each figure of merit weighs the cartridge characteristics differently. Some methods are based on fundamental physics (e.g. kinetic energy), while other methods are based on heuristic methods. Some of the more common figures of merit are:kinetic energy: favors high velocity, lower mass bullets (no diameter dependence)
momentum: favors moderate velocity, moderate mass bullets (no diameter dependence)
TKOF: favors large diameter, moderate velocity, heavy bullets
Thorniley Stopping Power: favors moderate diameter, moderate velocity, moderate mass bullets
Click to expand...

None of these methods truly consider bullet construction, with the exception of TKO, which dealt mainly with solid bullets. An expanding bullet, for example, may have better "stopping" power over another design, due to its increased wound channel as the jacket opens, even though it may be traveling at a lower velocity. Just as a large diameter solid, at low velocity may have better "stopping" power, due to its deep penetration, than a small diameter hollowpoint at max velocity.
Click to expand...

John taylor was an african big game hunter who probably never did any actual research into or put a lot of thought into the more common shooting events that involve human beings.
 
David R said:
My father told me if I got hit in the hand with a 45, with my arm extended, it would spin me around.

I am now 57 and do not believe that.
[emoji56]
David
Click to expand...
I will offer your dad some fine Pheonix waterfront property. Now, he is right about one concept he is trying to convey, a .45 does "work very well for it's intended purpose. My raggedy old a-- is here today because it works as intended. It just does!

I arrive at that opinion based on armchair research and scaredy as check experience. I guess everything I learned in research I proved in the "field.
 
hickok45 on knockdown power.............
Click to expand...

Ahhhh ok...? Kinda cool if youve never seen that kinda thing before.

He freely admits that shooting steel plates has no relevance to SD shooting. I think that (shooting plates and pins and the like) is where the “knockdown power” stuff got its foothold.

Back in the day pin shooters used calibers that where more likly to move the bowling pin off the table. Big heavy bullets moved the pins better, so thats what we shot. It was a natural conclusion that those same calibers were best for anti-people use as well.

Same with plate racks (to an extent). A hit wasnt good enough... you had to knock the plate over. A low hit with a light bullet might not do it. So heavy bullets ruled.

Poeple arent plates or pins and the bullet does not behave the same on impact. Hard vs. Soft media. Watch some gel tests (lots on utube) in most tests the block just wiggles
 
You must log in or register to reply here.
Back
Top