bullet weight vs. velocity regarding ME

The high velocity crack also makes fast moving rounds like .357 Mag extremely unpleasant and damaging to shoot without hearing protection. In a pinch, you can easily shoot 9mm or .45 ACP without becoming disoriented, but .357 Mag is sheer brutality, as shown by the dramatic difference in measured decibels.

I haven't seen a listing for 5.7 x 28 decibel levels, but I assume they would be higher than typical .45 at a minimum due to high velocity, as 9mm is.
 
You think that dividing by the 30822 constant used in the metric system to easily calculate energy in joules given weight (grains) and velocity (meters/sec) is somehow easier or superior to dividing by the 450436 constant used in the English system to easily calculate energy in ft-lb given weight (grains) and velocity (ft/sec)?
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I correct myself, using metrics for ALL parts of the equation, not just the outcome. The number you'd have to memorize then is neither 30622 nor 450436 but simply "2", given you can do with joules instead of ft-lb :D :D :D

All considered, I'd strongly propose a world where the Europeans do the numbers and the Americans make the gun laws :p
 
simonrichter said:
I correct myself, using metrics for ALL parts of the equation, not just the outcome. The number you'd have to memorize then is neither 30622 nor 450436 but simply "2", given you can do with joules instead of ft-lb
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Joule = 1/2 x kg x m^2/sec^2

Only way to get Joules by dividing by 2 would be to use kilograms for bullet mass.

Is it common to use kilograms for bullet mass in Europe? I've never seen a box of 9mm ammo described as containing "0.00745187 kg" bullets (115 grain).

simonrichter said:
All considered, I'd strongly propose a world where the Europeans do the numbers and the Americans make the gun laws
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Might be a good idea to leave the numbers AND the gun laws to the Americans ... ;)
 
The proper formula for calulating the Muzzle Energy of a projectile is:

Velocity * Velocity*Projectile weight (in grains)/450240 = Energy (in foot pounds).

This should clarify matters.
 
Ballistic tables are indices for the naive. Go with momentum. Momentum will provide the more accurate indication of penetration.

A general rule of thumb is bigger and heavier is better.

I'd carry a 1911A1 with 230 grain ball ammo without slightest hesitation or concern. But 8 230 grain rounds in a 1911A1 is heavy.

The 1911A1 earned its stellar reputation with 230 grain ball ammo at about 850 FPS.
 
The gun gets the momentum of the bullet + powder/gasses.
Or did you mean, when all the dust settles, there is no momentum.
 
Wow.... Let the terminological inexactitude and acrimony begin, I guess...

Kinetic Energy = (mass x velocity x velocity)/2.

Momentum = mass x velocity.

To determine the K.E. (in foot pounds) of a projectile of a particular weight (in grains), launched at a particular velocity (in foot/seconds), multiply bullet weight x velocity x velocity, and divide the product by 450240. I'll leave it to the math enthusiasts to break down the dimensional analysis.
Those same math enthusiasts will also tell us that momentum is the 1st derivative of Kinetic energy with respect to velocity. The two schools of thought concerning which of these measurements are the more valid indicator of a round's ability to incapacitate a determined attacker with a well-placed shot delivered to the torso (qualifications mine) break down roughly into the kinetic energy enthusiasts vs. the momentum enthusiasts. NEITHER of them seem to be very fond of considering bore area of the projectile in question when trying to predict terminal effect, but the kineticists seem to ignore it more aggressively than the momentum fans.

Let's assume we have a 160 grain projectile launched at 1000 f/s. Its K.E. will be about 355 foot pounds, and its momentum will be about 23 pound-feet/second. Now, let's pretend that, if we decrease the projectile mass by 10%, we can (safely) increase muzzle velocity by exactly 10%. The resulting load's momentum remains unchanged, but its kinetic energy increases by roughly 10%. The kineticists will claim that the round's ability to stop a determined attacker has increased because its kinetic energy is increased (some particularly deluded kineticists will argue that its capacity to do so has increased by roughly 10%, with the K.E.), while the momentum fans will argue that its fight-stopping capacity had actually DEcreased, or not changed, depending on whether they count the faster round as less able or equally able to penetrate its target. Neither has a monopoly on being right.

The 160 grain projectile at 1000 f/s reflects what may be obtained from a true .38 Special +P load, fired from a barrel usually longer than 6", and has a reputation for being an adequate but not necessarily outstanding fight stopper. That round's muzzle energy is almost identical to that generated by a 230 grain bullet with a muzzle velocity of 830 f/s, which are specs obtainable by the .45 ACP from a 5" or shorter barrel. The muzzle energies are the same, but the heavier slug at the lower velocity has 20% more momentum, and 60% greater bore area.

Which one do most people believe enjoys a better reputation as an efficacious fight-stopper? I don't really have to spell it out, do I?

The hottest 9mm handload that I can find enjoys 14 or 15 % greater muzzle energy than the .45 ACP or .38 Special +P+(?). Its momentum is roughly 10% less than the hot .38's and 30% less than the .45 ACP ball round. Its relative fight-stopping efficacy is well-correlated with those deficits, also.

NOW, let the fur fly.
 
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Yes, the penetration of a solid bullet in flesh (or ballistic gel), it correlates more closely to momentum then to kinetic energy. Thing is, though, heavy and slow handgun bullets, even those which are pretty anemic (by modern standards) loads, will penetrate more then enough very easily. Increasing it doesn't have purpose.

Something like, by now, 100 year old 45 ACP or .45 Colt with ball ammo, will easily penetrate well over 20" of gel, firing 200-230 gr bullets at some leisurely 800-850 FPS. Now, sending a 0.45 caliber slug with more then enough penetration is going to still work, just like it has worked for a bit over a century before the advent of modern ammo and works to this day for those who mustn't use modern ammo (eg. every army out there).

In fact, if you don't want to or can't (military, civilians in some EU countries, etc) use expanding ammo, you might as well stop here, ignore various +P rounds, pick a SWC (revolver) or ball (semi-auto) in large caliber with a heavy and slow round, and if it comes to that, be pretty confident with what you have.

However, expanding ammo isn't just some passing fad, and it requires velocity to happen (the bullet will consume a significant part of it's own kinetic energy to deform), and here the light and fast shines, as long as sufficient penetration is there. This is why you see so many +P rounds nowadays; they actually do need the extra energy to expand and still penetrate sufficiently.


Is it common to use kilograms for bullet mass in Europe? I've never seen a box of 9mm ammo described as containing "0.00745187 kg" bullets (115 grain).
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It is common to express it in grams, so we would say that this 9mm fires 7.5 gram bullets. You can just plug in the number in the equation and then divide the result by 1000 to get Joules. Isn't the metric system grand? ;)
 
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Branko, I think we're in agreement, we each just said the same thing in ways that appear different, but are not. I'M a big believer in momentum as a better predictor of fight-stopping efficiency than kinetic energy. But I also believe that the projectile's diameter (and bore area) cannot be ignored, because it helps determine the exsanguination rate from the wound inflicted.

The .45 ACP and the .38 Special can both launch a 200 grain projectile at about 800 f/s. Each will have the same kinetic energy and momenta. But I suspect that the .45 caliber projectile will be superior in terminal performance, because the hole it creates as it penetrates will be 60% greater in area (assuming similar depths of penetration).
 
simonrichter said:
I correct myself, using metrics for ALL parts of the equation, not just the outcome. The number you'd have to memorize then is neither 30622 nor 450436 but simply "2", given you can do with joules instead of ft-lb
Click to expand...

branko said:
It is common to express it in grams, so we would say that this 9mm fires 7.5 gram bullets. You can just plug in the number in the equation and then divide the result by 1000 to get Joules. Isn't the metric system grand?
Click to expand...

Seems that some people think that you have to divide by 2 in the metric system, some think you have to divide by 1000. Some seem to think that projectile mass is commonly expressed in kilograms (I believe that simonrichter is European), some think that it is commonly expressed in grams (not sure if branko is European or not). Isn't keeping your units straight grand? :cool:

On the other hand, some seem to think that kinetic energy (E = (MV^2)/2) is the same thing as nuclear energy (E = MC^2). I suppose it takes all types to make the world go round! :)
 
Years back, there were two separate means of measuring energy. Kinetic energy and momentum. Kinetic energy, by reason of squaring velocity in the equation, led the high velocity rounds to higher energy figures, and momentum led higher mass projectiles to higher ratings.

Both types of cartridges perform differently. At one point, the223 was banned in my state for larger game, yet the .357 was approved. Since that time, we've standardized energy stats at KE and left it at that.
 
There is no Holy Grail of handgun bullets. We can spend considerable time developing theories, constructing hypotheses, and testing them. However, myriad variables will render such tests less than panacea. In fact, there is no such handgun bullet panacea. It just doesn't exist.

We can think this through until our national debt is paid off, and we'll still have resolved very little.

My primary rule of gunfighting is don't get in one. That's the only way of assuring survival. My second rule of gunfighting is to not get shot. A fiberglass examination table with a wooden block under my lifeless head ain't appealing to me. In a gunfight, a bad guy or bad guys will be putting rounds on you. Avoid that at all cost. The best way to avoid bad guys putting rounds on you is to not get in a gunfight.

Go with O'Reilly's law which states that Murphy was an optimist. Expect more than one bad guy. Expect that they will have trained and know what the heck they're doing. Expect that they have planned their crimes. They will have probably murdered before your encounter with them. So their killing you will mean nothing to them. Remember that if you're in a gunfight, it's because a bad guy or bad guys want to kill you. If bad guys are under the influence of illegal drugs, expect them to take an awful lot of damage and keep fighting.

Bullet design is on a lower rung. I'd never expect a bullet to perform like those pretty photos that ammo companies love to publish. With a .45 ACP, I'd be happy with 230 grain ball. After all, I'm looking for penetration. A .40 S&W is a good choice provided one has a standard capacity magazine. There is a valuable tactical advantage to not having to reload. For me, I'd rather have 9 .45 ACP rounds than 11 .40 S&W, 9MM, or 10MM rounds. But that's just my take on it.

I don't want to digress to a caliber debate. You guys have already made up your minds about what will work for you. For me, bigger and heavier is better. Others will see it differently. I'm good with that. I will not try to convince anyone that I'm right.

There is no such thing as a handgun man stopper. That one exists is gun magazine fantasy. In fact, I consider the .357 Mag as mediocre as a self-defense weapon. But I also know that others will see it differently. I'm good with that. BTW, when I have carried a .357 Mag for self-defense, it was always loaded with .38 Special 158 grain LSWC or LSWCHP +P.

An autopsy is not a pretty procedure to watch. Do not allow yourselves to prematurely become the subjects of them.
 
You have to also take into account that each encounter has a history. It isn't just looking out the window and finding a gun at your head. Let's all get rid of hindsight as an excuse, or blame it on being unprepared.

Carry your gun and have it accessible. Keep the eyes up and open, not on the keyboard. Profile everyone. Pay attention to small details of other people and what they do. If you are forewarned of a possible encounter, it will be a very different outcome than if you had been taken completely by surprise.
 
Momentum: "ability to brute force punch a path through objects"
Energy: "ability to destroy everything surrounding that path as you punch through"

Simple. ;)
 
45 auto, at what point did I say that they were the same? I DIDN'T!
Is kinetic energy the same as momentum? IT ISN'T!
What is the difference? Momentum is measured by mass times velocity, and kinetic energy is the number found when mass times velocity is squared, ad then divided by two.

THEY ARE NOT THE SAME, AND YOU CAN FIND THIS HIGH SCHOOL PHYSICS ONLINE!
In the past, people DID argue the point of whether KE or simple MxV best represented energy placed on target. It is also a fact that some people even used bars of soap to measure bullet efficiency. Before jello, and the standard of KE being accepted and momentum being dumped as an alternate standard, educated men argued whether the momentum of a 235 grain .45 was more effective than a.222, for example.

Mehavey is absolutely correct. High momentum is measured by the energy being transferred to the target with little destructive force. High kinetic energy is demonstrated by destruction of the target. Where a steady stream of.44 magnum will eventually bow a plate inward, a few rounds of .22-250 would punch holes through steel that isn't meant to absorb this kind of round.

There is a reason that armor piercing rounds are generally high velocity and light weight. This combination destroys armor.
 
By the way, using a high school manual to show that your own erroneous interpretation of my own clearly stated information is a classic example of tossing out an argument that doesn't even remotely fit the previous assertion.
 
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