Why carry a .40 or.45

[MojoTexas]

If you compare energy, expansion and penetration, the 9mm is at least the equal of the .45 acp from a scientific point of view in the size weapon that most people would carry. If you really want to start an argument, the .40 S&W is actually better than either the 9mm or the .45. It has about the same penetration as the 9mm (greater than the .45 acp), the same expansion as both the 9mm and the .45 acp, but higher energy than either of those loads. So theoretically, it should have the greatest stopping power of the three.

That means the 10mm Auto has all three (9mm, .40 S&W, and .45 ACP) beat, since it's just a .40 S&W cartridge that is longer with more powder (sort of like the relationship between .38 Special and .357 Magnum). One of these days I'll buy me a Wilson Combat 1911 chambered in 10mm...

MojoTexas

[MojoTexas]

How about this would you rather get hit in the chest with an 80mps baseball or a 30mps 400lb bolder. The velocity of the smaller and lighter (less mass) baseball will not make up for the larger and heaver (more mass) 400lb bolder. Both can kill you, but one will have a better chance of stopping you then the other and is more lethal.

Not to nit-pick, because I understand what you're saying, but you'd have to balance the two equations for it to be a fair comparison.

The formula for kinetic energy is:



If you have a baseball (which averages about 145g) traveling at 80 m/s (meters-per-second), then the translational kinetic energy would be 464 joules.

If you have a 400 lb boulder (181.44 kg) travelling at 30m/s, the translational kinetic energy would be 81,646.62 joules.

A better example, using the 30m/s velocity, would be a 2.27 lb rock (1.03 kg), which would be an equivalent amount of energy given the differences between velocity and mass.

Yeah I know I'm a geek....

MojoTexas

[baldeagle]

If you compare energy, expansion and penetration, the 9mm is at least the equal of the .45 acp from a scientific point of view in the size weapon that most people would carry. If you really want to start an argument, the .40 S&W is actually better than either the 9mm or the .45. It has about the same penetration as the 9mm (greater than the .45 acp), the same expansion as both the 9mm and the .45 acp, but higher energy than either of those loads. So theoretically, it should have the greatest stopping power of the three.

That means the 10mm Auto has all three (9mm, .40 S&W, and .45 ACP) beat, since it's just a .40 S&W cartridge that is longer with more powder (sort of like the relationship between .38 Special and .357 Magnum). One of these days I'll buy me a Wilson Combat 1911 chambered in 10mm...

MojoTexas

And indeed, the 10mm muzzle energy readings are off the charts compared to all the other calibers except the .357 Magnum. So if stopping power is really your top criteria for choosing a SD weapon, then it seems the 10mm or .357 Magnum would be the best choices.

[baldeagle]

Hatcher Formula
Used to decide stopping power of a pistol in SD, the best stopping power is 50 with anything going over 55 having diminishing return and more recoil

45 = 60.7
40 = 59.4
10 = 62.1
9 = 39.9
380= 18.3

Mass x Velocity = momentum

Momentum = penetration depth.


Quick list of bullet stopping power based on the formula

http://www.abaris.net/info/ballistics/hatcher-table.htm" onclick="window.open(this.href);return false;

First of all, I don't really like formulas that include opinions unless you can see how the opinion is derived from actual evidence. Having said that, if you're going to play that game, you need to use an even playing field. That means you get your numbers for each caliber from the exact same ammo.

Using Hollow Point (expanded), which is the most likely SD round used by most people who carry, the numbers are:
45 = 91.989
40 = 68.838
10 = 77.994
9 = 43.190
380= 28.455

I'm not prepared to agree to the statement that 50 is ideal and above that is less than ideal, because I don't know where you got that from, but assuming it's correct, the caliber closest to that ideal number is the 9mm.

[USMC-COL]

For me it is the stopping power , Ive heard alot stories from alot of friends that are LEO and for them a 9mm just doesnt cut it for them. So they recommend at least a .40 if not a .45 which most LEO carry .45 these days.
But this is ONLY my opinion , no more no less

The largest police department, the NYPD, carries 9mm Glocks with GD 124-gr +p ammo. They are happy with the results. They have no plans to change.

[Bart]

A better example, using the 30m/s velocity, would be a 2.27 lb rock (1.03 kg), which would be an equivalent amount of energy given the differences between velocity and mass.

Let's stick with the 400 lb boulder from his example. I would rather bump my head on a 400 lb boulder at a little over 2 m/s (5 mph) then get smashed in the head by a baseball at 80 m/s (nearly 180 mph)

[rm9792]

For me it is the stopping power , Ive heard alot stories from alot of friends that are LEO and for them a 9mm just doesnt cut it for them. So they recommend at least a .40 if not a .45 which most LEO carry .45 these days.
But this is ONLY my opinion , no more no less

The largest police department, the NYPD, carries 9mm Glocks with GD 124-gr +p ammo. They are happy with the results. They have no plans to change.

I would be willing to bet that stopping power was not the overriding concern. I say price and service was their concern. Possibly extremely simple manual of arms as well.

[Excaliber]

For me it is the stopping power , Ive heard alot stories from alot of friends that are LEO and for them a 9mm just doesnt cut it for them. So they recommend at least a .40 if not a .45 which most LEO carry .45 these days.
But this is ONLY my opinion , no more no less

The largest police department, the NYPD, carries 9mm Glocks with GD 124-gr +p ammo. They are happy with the results. They have no plans to change.

Then again, they carried 158 grain solid point semiwadcutter ammo for many years after everyone else had gone to hollowpoints.

They also refused to consider hollowpoints when they issued the original Glock pistols a number of years ago. The brass was happy with the politically more acceptable FMJ ammo and changed only after taking heavy flak because it regularly overpenetrated bad guy targets that weren't terribly impressed by the rounds' passage and kept taking out civilians and cops on the other side.

The current rabidly anti 2A mayor would never allow NYPD to use any ammo whose caliber started with a 4. That agency's choices have been historically and currently constrained by factors other than optimum performance. This makes the fact that they use the 9mm not necessarily good evidence of superiority over larger rounds. That being said, 9mm Gold Dot is a very fine round, and is probably one of the top 3 or 4 service loadings in that caliber. If you're going to carry a 9mm, it's one of the best choices out there. However, NYPD took a long and circuitous route to arrive at this selection.

[MojoTexas]

A better example, using the 30m/s velocity, would be a 2.27 lb rock (1.03 kg), which would be an equivalent amount of energy given the differences between velocity and mass.

Let's stick with the 400 lb boulder from his example. I would rather bump my head on a 400 lb boulder at a little over 2 m/s (5 mph) then get smashed in the head by a baseball at 80 m/s (nearly 180 mph)

I think you're imagining your head striking the boulder, not the other way around. Your head traveling at 5 mph does not have the same force as 400 lbs traveling at 5 mph. Imagine if you will if you were buried to your neck in a frictionless vacuum, and had a 400 lb boulder rolling at 5 mph at your head. If it struck your head at the same speed as a human's slow jog, I think it would do more than give you a little lump.

Here's another example with the same force: how about a 10 lb sledgehammer striking your head at 14.3 m/s (32 mph)? The 10 lb sledgehammer would have a mass of roughly 4.54 kg, and traveling at a velocity of 14.3 m/s would yield the same force in joules as the baseball at 180 mph. Both would probably be lethal.

I guess what I'm saying is that from a physics perspective, the faster you can push a round the better, since as the velocity increases the energy increases exponentially. There are other factors involved in "stopping power" however, such as bullet expansion, hydrostatic shock, etc.

MojoTexas

[Bart]

If someone is buried in the ground and then shot, that makes sense. However, most criminals and victims who are shot are not buried or held immobile at the time. But in those special cases..........

[MojoTexas]

If someone is buried in the ground and then shot, that makes sense. However, most criminals and victims who are shot are not buried or held immobile at the time. But in those special cases..........

My point is that if you're going to compare two different projectiles moving at different velocities, they will be roughly equal if the force is equal. The example of the baseball and the 400-lb boulder was not equal mathematically.

[Bart]

My point is that if you're going to compare two different projectiles moving at different velocities, they will be roughly equal if the force is equal. The example of the baseball and the 400-lb boulder was not equal mathematically.

I agree completely. I was just having some fun.

I think shot placement is more important than any other factor. Carry a gun you can shoot well. Many people can shoot a .45ACP 1911 well with some training. If you're in a place that prohibits open carry or prohibits all carry, concealment becomes a factor. Some people can conceal a 1911 well and others can't. I think concealing a 1911 well is harder than shooting a 1911 well for most people.

[danpaw]

If you ever have to shoot someone you better hope it is an algebra teacher, otherwise he may not appreciate the awesome power of the 9mm. I'll just keep packing the .45 and leave the 9mms in the safe, but thanks for the input.

[baldeagle]

There were some links posted somewhere on this site here is one.
http://www.firearmstactical.com/pdf/fbi-hwfe.pdf" onclick="window.open(this.href);return false;

There was another with drawings of wound cavity that was good also. Just can't find it.

Thanks for the link. I'm still reading, but this one statement really struck me. "The impact of the bullet on the body is no more than the recoil of the weapon." If you think about it, that makes sense. Newton's law says that for every action there is an equal and opposite reaction. The recoil you feel will be the same as the impact of the bullet felt by your adversary. If you think about the recoil you feel when you're shooting, that isn't enough to knock you over or even cause you to lose your balance, unless it's a very large caliber weapon and you are unprepared for the recoil.

[baldeagle]

If you ever have to shoot someone you better hope it is an algebra teacher, otherwise he may not appreciate the awesome power of the 9mm. I'll just keep packing the .45 and leave the 9mms in the safe, but thanks for the input.

The danger of this kind of thinking is that you will be unprepared for an adversary who is hit by your caliber of choice and keeps fighting. If you are truly expecting a "one shot stop", what will you do when that does not occur? Will you hesitate? That hesitation could get you killed.