Very good article comparing 9mm and .40SW for self defense

[TGO David]

Tungsten...I had a P2000 and even sold my P30 for the same reasons. The trigger. HK's are wonderful...but 15 rds and a consistent trigger pull in a G19 are hard to beat. Thats what I carry now.

I wish I had thought to ask you about shooting your G19 at the range last weekend. Maybe some other time. I had a G23 a few years back so I know the dimensions are similar; just wondering what the 9mm feels like in that frame.

[Guest bigbuck_tn]

I have recently had the same eureaka! moment while thinking about 9mm vs 40. My wife is going to go get her permit in a few months and it got me to thinking about us using the same caliber guns. Then that led me to think about the effectiveness difference between calibers and suddenly this light went on in my head.

0.355" vs 0.400"

0.005" Diameter difference. 0.0025" Radius difference.

Some Chrysler brake rotors have a more allowable variation in Lateral Run Out.

Then I got to thinking about KE and all that stuff. So then I thought about it. If KE is what stopped people then wearing a bullet proof vest should increase your chance for a stop. All the KE is dumped right there into your chest. Instantly practically. Granted it is hopefully on your chest and not inside but if jostling your organs with KE makes you stop they should get pretty jostled then.

That leads me to believe that accuracy is #1(to hit something vital), #2 is penetration (to get to something vital), and lastly would be frontal diameter(to give more room for error with #1).

Personally I think I would rather have 2 or 3 more chances of making #1 than to have more of #3.

Glad to see I am not the only one going over to the weenie cartridge side.

[Marswolf]

That leads me to believe that accuracy is #1(to hit something vital), #2 is penetration (to get to something vital), and lastly would be frontal diameter(to give more room for error with #1).

Personally I think I would rather have 2 or 3 more chances of making #1 than to have more of #3.

There is an obvious joke there about making #1, but of course I won't mention it.

But your reasoning is largely what lead me to go with a 9mm in the 80s rather than the "standard" 45 ACP for field use. 16 rounds of 9mm before reloading sounded a lot better than 8 rounds. I still use it in the field.

But for closer urban ranges, I decided to go with the larger 40 S&W round.

If I had to choose only one, I'd go with the 9mm.

[TGO David]

There's some good thinking going on in this thread.

For what it's worth, my daily carry has become my HK P2000 .40SW since it's the one autoloader that I have right now that (a.) isn't a 1911 and (b.) carries more than 8 rounds of ammo and (c.) that I have an IWB holster for. Twelve cartridges of .40SW isn't too shabby although three more cartridges of 9mm would be nice.

I am still very interested in picking up a Glock 19 sometime soon, but that will have to wait until I have a spare $500 to sink into another firearm.

[molonlabetn]

I have recently had the same eureaka! moment while thinking about 9mm vs 40. My wife is going to go get her permit in a few months and it got me to thinking about us using the same caliber guns. Then that led me to think about the effectiveness difference between calibers and suddenly this light went on in my head.

0.355" vs 0.400"

0.005" Diameter difference. 0.0025" Radius difference.

Some Chrysler brake rotors have a more allowable variation in Lateral Run Out.

Then I got to thinking about KE and all that stuff. So then I thought about it. If KE is what stopped people then wearing a bullet proof vest should increase your chance for a stop. All the KE is dumped right there into your chest. Instantly practically. Granted it is hopefully on your chest and not inside but if jostling your organs with KE makes you stop they should get pretty jostled then.

That leads me to believe that accuracy is #1(to hit something vital), #2 is penetration (to get to something vital), and lastly would be frontal diameter(to give more room for error with #1).

Personally I think I would rather have 2 or 3 more chances of making #1 than to have more of #3.

Glad to see I am not the only one going over to the weenie cartridge side.

.045" diameter difference, actually. And when dealing with expanding projectiles that doesn't constitute a major difference. But, don't forget that the frontal area of the projectile is a squared function... which means that even though the diameter difference is only a few percent, the nominal frontal area difference is far more significant.

KE is a biased measure of a bullet's destructive power which is constrained to the properties of the media which it strikes... a more suitable universal measure would be MV over frontal-area, which would truly provide a better comparison of the potential and distribution of 'work' which projectiles could perform upon a given medium. At least in terms of most handgun ballistics, anyways, since hydrostatic shock-waves are a major factor in the wounding potential of higher velocity rifle projectiles... and those are best predicted by KE.

All in all, yes, what matters most is where the bullet strikes on any given day and whether it can plow through enough flesh. But all that being equal, there certainly is a difference in the efficiency of higher 'power' rounds to incapacitate more quickly, physiologically. The biggest variable in incapacitating humans is not just physiology... but psychology as well.

[Marswolf]

One of the things I have learned over the years is that humans are not deer.

You shoot a deer, and it will fight to flee until it can no longer do so.

Humans sometimes do that, but also sometimes will collapse with minor wounds. You don't know which kind of human you will get when you shoot it, so it's a good idea to go for areas where you can do a lot of neural damage, or places that make them bleed a lot.

Knowing where those spots are and keeping a cool head will go a long way toward keeping you alive and making sure that they are not.

[Guest bigbuck_tn]

.045" diameter difference, actually. And when dealing with expanding projectiles that doesn't constitute a major difference. But, don't forget that the frontal area of the projectile is a squared function... which means that even though the diameter difference is only a few percent, the nominal frontal area difference is far more significant.

Whoops. Your right. Math is my worst subject.

The squared function of the frontal area still only constitutes a difference of 0.126" (9mm) - 0.16 (40) = 0.034"

That is still only 34 thousandths of an inch. A little over 1/32 of an inch.

Now with a 45 you are getting significant 0.0765". So 76.5 thousandths. About 5/64th of an inch.

So you are getting at best between 1/32 to 5/64ths of "guaranteed" difference for giving up between 3 and 8 more opportunities with increased recoil.

Now there is a greater difference with expanding ammunition that again increases as the diameter increases but I consider that an uncontrolled variable in the equation and drop it. You can't guarantee it will expand, if it does, good, if it doesn't you better have hit what you meant to in the first place.

[Magiccarpetrides]

.045" diameter difference, actually. And when dealing with expanding projectiles that doesn't constitute a major difference. But, don't forget that the frontal area of the projectile is a squared function... which means that even though the diameter difference is only a few percent, the nominal frontal area difference is far more significant.

KE is a biased measure of a bullet's destructive power which is constrained to the properties of the media which it strikes... a more suitable universal measure would be MV over frontal-area, which would truly provide a better comparison of the potential and distribution of 'work' which projectiles could perform upon a given medium. At least in terms of most handgun ballistics, anyways, since hydrostatic shock-waves are a major factor in the wounding potential of higher velocity rifle projectiles... and those are best predicted by KE.

All in all, yes, what matters most is where the bullet strikes on any given day and whether it can plow through enough flesh. But all that being equal, there certainly is a difference in the efficiency of higher 'power' rounds to incapacitate more quickly, physiologically. The biggest variable in incapacitating humans is not just physiology... but psychology as well.

Seems like i had heard somewhere (not wikipedia ) that due to its monstrous amount of KE if one was shot with a .50AE and wearing a bulletproof vest even if the vest stopped the bullet the energy transfer would be so immense that you would still die from massive internal bleeding. Dont know what made me think about that...maybe my senseless lust for a .50 Desert Eagle. Great articles and info btw....heres a thought. Whats better carrying an 8 rd .45 and a BUG or carrying extra mags in a SD scenario?

[strickj]

Whats better carrying an 8 rd .45 and a BUG or carrying extra mags in a SD scenario?

I would dreader have more smaller rounds then fewer bigger rounds.This sums it up well

Originally Posted by DMark

The best REAL combat handgun shooter that I ever knew was killed in the middle of a fight with his right hand still holding his slide-locked 1911 and the other with a fresh mag ready to reload. It was clear from the bodies around him that so long as his weapon was running he was winning. I have often wondered if he'd be alive today for the want of a few more bullets over bigger bullets.........