Handgun Stopping Power - Efficacy?

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So... a golf ball hit from Tiger Woods or a baseball thrown from Randy Johnson? The right caliber can make you Tiger Woods or Randy Johnson. Alright!
 
Let's look at some (not all ) of what the figures published by ammo manufacturers and shown in their catalogs can tell us and I'll use the .45 acp and the .357 Sig as examples (excuse the format here) :
.45acp
Black Hills 230 gr. JHP: 25yds. 50yds. 75yds. 100yds. 150yds
Velocity at muzzle: 900fps 879 859 841 823 790
Energy at muzzle: 412 395 377 361 346 318

.357 Sig
Black Hills 125 gr. JHP 25yds. 50yds 75yds 100yds 150yds
Velocity at muzzle:1350 1263 1188 1124 1071 991
Energy at muzzle: 506 443 392 351 319 273

Energy is a measure of the ability to do work. Bullets do work. It requires energy to overcome the resistance of the rifling, to resist air pressure, to impact and penetrate an object, to expand. Much energy is transferred in the form of heat and noise.

Note that the .45 acp round above starts at a velocity of 900fps and at 100 yds has lost 77fps. The .45 had 412 ft pds of energy at the muzzle and had lost 66 ft.pds of energy at 100 yards. Compare this to the .357 Sig which had lost 279 fps of velocity at 100 yards and 124 ft.pds. of energy at 100.

These figures tell you more than what I mention above and you can see how they will be more useful in rifle rounds that in service handgun cartridges.

tipoc
 
I'm just saying that all the efficacy numbers for handguns that I have calculated seem about right. Personally, I do factor in momentum, but as penetration, not stopping power.

Here's my penetration formula for FMJ's.
(Grains x Velocity) / (Caliber x 100)^2

I think it might be more realistic to have area instead of caliber, but whatever.
I put the two number together, like this:

.45 ACP 230gr FMJ 830 fps = 56 / 93

.357 SIG 125gr FMJ 1350 fps = 50 / 134

9mm Luger 124gr FMJ 1120 fps = 34 / 110

You keep penetration and stopping power seperate because this is not killing power, it's stopping power. Don't try this formula with Glasers, etc.
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Since most people use JHP for protection (maybe not in NJ) your equation seems rather meaningless. I'll stick with Mr Newton and his formulas.
 
I thought of the idea of "efficacy" myself after messing around with different formulas but recently I found that one L. Niel Smith had thought of the same thing. I think it is a pretty good measure of a cartridge's " stopping power", but I am unsure about rifles after I found a .50 AE rated higher than a .30-06. (314 vs 216)

Efficacy = frontal area x ft-lbs energy
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I don't mean any offense, but unless this "efficacy" formula has been statistically correlated to some meaningful quantitative data, it is pretty much worthless pseudo-science. The units of "efficacy" are in^2*ft*lbs, or length^3*force. What exactly does that mean? What physical concept does "Volume*force" correspond to in terms of cartridge effectiveness? Notwithstanding the arbitrary mixing of inches and feet in the same formula and the reductivist notion that one number can adequately capture all the variables involved in actual cartridge effectiveness, the fact that a .30-06 has 2/3 the "efficacy" of a .50 AE should raise a red flag.

The ability to multiply numbers together should not be mistaken for the ability to create a scientific model.
 
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Obviously a 70,000 grain bowling ball moving 1fps is not analogous to a typical self-defense handgun bullet, nor is a 5 or 6 grain BB moving at 15,000 fps (to equal 500S&W energy).

The problem with comparing the practical differences in performance between typical handgun self-defense calibers is that they're so similar in performance. Trying to draw conclusions from extreme examples is fruitless.

This question has been hashed & rehashed for the last century or so with no definitive answer. Just a tiny bit of thought will make it plain that the reason the debate rages on is NOT because there's a lot of difference in performance. If there were, it would be very simple to pick a winner...
Click to expand...

I don't mean any offense, but unless this "efficacy" formula has been statistically correlated to some meaningful quantitative data, it is pretty much worthless pseudo-science. The units of "efficacy" are in^2*ft*lbs, or length^3*force. What exactly does that mean? What physical concept does "Volume*force" correspond to in terms of cartridge effectiveness? Notwithstanding the arbitrary mixing of inches and feet in the same formula and the reductivist notion that one number can adequately capture all the variables involved in actual cartridge effectiveness, the fact that a .30-06 has 2/3 the "efficacy" of a .50 AE should raise a red flag.

The ability to multiply numbers together should not be mistaken for the ability to create a scientific model.
Click to expand...


Two sensible posts that pretty much sum it all up. (bolds inserted to highlight)
 
Before wading in and reading some of the thread
past the O.P.'s first post my initial impression and
experience is whatever the 2 digit number's formula
it appears linear with kinetic energy which IMO is not
indicative of Stopping power Efficacy.

What does a 147 gr. 9mm Luger +P say 1100 FPS
comes out to in the Formula?

In fact any formula that rates 186 gr. over 230 gr.
is worthless IMNSFO.


Randall
 
I thought that this issue was settled...

I've been out of "gun talk" for several years, but the last I heard that a study was done that equated Wound Channel (depth and circumferance) with stopping power.

The thought being that the greater the disruption of tissue the more Systemic Shock delivered.

Has this theory gone away???
 
What does a 147 gr. 9mm Luger +P say 1100 FPS
comes out to in the Formula?
Click to expand...

It comes out to 39, rather less than the .45ACP's 59.
.45 ACP+P 230gr 950fps comes out to 74.

So that 9mm+P load is 2/3 as good a stopper as standard .45.
And 1/2 as good as .45ACP+P.

Standard 9mm gets a 34. (124gr at 1120fps)
 
Has this theory gone away???
Click to expand...
No. It's just that the actual, real world differences in the size of the wound channels between the popularly bantered calibers is not significant enough to make a huge difference in so-called "stopping power". Add into the equation any number of variables from person to person and situation to situation, and shot placement becomes way more important than the number stamped on the side of your gun.
 
It comes out to 39, rather less than the .45ACP's 59.
.45 ACP+P 230gr 950fps comes out to 74.

So that 9mm+P load is 2/3 as good a stopper as standard .45.
And 1/2 as good as .45ACP+P.

Standard 9mm gets a 34. (124gr at 1120fps)
Click to expand...

Did you not read post #31?? The poster very politely exposed the flaws in your reasoning yet you continue to represent your findings as fact.

Please stop posting this nonsense without a "junk science bs" disclaimer so no one takes it seriously by mistake!:D
 
One major problem I see with your math: 'frontal area' is not the same as caliber. And, with the exception of .40 S&W, most rounds are conical, creating further problems. Furthermore, momentum is a function of energy and is reliant upon the density of the material it is traveling through, so the actual formulas are quite a bit more complex than the postulate that you posted here.
 
No. It's just that the actual, real world differences in the size of the wound channels between the popularly bantered calibers is not significant enough to make a huge difference in so-called "stopping power". Add into the equation any number of variables from person to person and situation to situation, and shot placement becomes way more important than the number stamped on the side of your gun.
Click to expand...

while shot placement is of course more important than anything, people have posted data based upon police and fbi shootings that show that certain rounds, particularly the .45 and .357, have a marginally higher percentage of one shot stops. i believe some of the .45 and .357 loads were around 96% one shot stops, whereas 9mm was only around 83%. that's a difference, even if not huge.
 
Stopping power is only as good as your aim. Virtually any caliber will stop an attack if placed properly. And, virtually any caliber will fail to stop an attack if improperly aimed. We are not talking about grenades and mortars. In a real live gun fight, I believe that shot placement, movement and cover will dictate the outcome over caliber any day of the week.

Remember... people aren't going to just stand their like a block of ordinance gelatin and let you place rounds COM all day. Pistol combat is a dynamic and violent environment with many variables. Caliber is just one of the minor variables. Hitting your target is a much heavier weighted variable.

You can theorize all you want... it is merely academic. Unless you hit your target where it matters, you will loose the gunfight.
 
Why does this matter? It still goes back to where you manage to place the bullet. I don't care if your magic bullet has an efficacy of "56", do you expect to stop an aggressor if you only hit his big toe?

In life or death situations where you may be dealing with crazy on a week-long meth binge, scoring big in "efficacy" doesn't mean anything if the BG doesn't want to cooperate. I occasionally recount a story told to me by a local SWAT Entry Team leader about how they engaged a man up a stairwell with aimed .45ACP rounds into his COM but he kept coming, it took a 12 gauge to finally put him down. Subsequent autopsy showed that his heart was destroyed by initial bullets, but he was just too stubborn to die.

Figure that into your math.
 
All I'm saying is that this formula seems to beat the Hatcher, TKO, Energy and Momentum formulas and produce realistic values.
Nobody's arguing that shot placement is not the most important thing, but most everyone will agree a hit with a .45 beats the same hit with a 9mm.
 
Remember the guy in Quincy, Illinois?
Hit by over 30 9mm 100gr softpoints, but still up and running.
It took a pair of 12-gauge slugs to take him out.
 
the fact that a .30-06 has 2/3 the "efficacy" of a .50 AE should raise a red flag.
Click to expand...

Of course, I've never heard of anyone surviving a hit centre-mass with the .50AE.
 
This thread reminds me of an article that I read sometime ago about a big game hunter/author who had developed his own formula for determining the optimal game weight that a particular caliber, bullet weight and velocity would be optimal for. Not surprisingly, he named it the "Optimal Game Weight" equation. :) I cannot recall if it was based upon momentum or kinetic energy, but it did seem to yield some interesting, if not, reasonable numbers the result of the equation being expressed in pounds of game weight.

I've come up with a similar equation, which I refer to as "Terminal Application Value" or "TAV", that is based upon a derivative of the momentum (ρ=mv) and the cross sectional area of the bullet and yields its results in pounds of target/threat weight. The number generated is neither a "minimum" nor a "maximum", but rather a "ballpark optimal value".

While I will not provide the equation here for general consumption, the numbers that it yields in terms of TAV are interesting and give me (at least ;) ) a perspective on what my chosen calibers will do. The TAV equation assumes a COM "hit" and the employment of an adequate SD bullet design.

Here are some values from some of the more common SD service calibers generated by the equation:

9x19

115 gr. @ 1155 fps. TAV= 229.3 lbs.
124 gr. @ 1120 fps. TAV= 234.5 lbs.
147 gr. @ 990 fps. TAV= 240.0 lbs.

.40 S&W

155 gr. @ 1155 fps. TAV= 299.9 lbs.
165 gr. @ 1125 fps. TAV= 305.5 lbs.
180 gr. @ 1000 fps. TAV= 300.8 lbs.

10mm

175 gr. @ 1290 fps. TAV= 336.9 lbs.

.45 ACP

185 gr. @ 950 fps. TAV= 335.1 lbs.
230 gr. @ 825 fps. TAV= 348.2 lbs.

:)
 
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