Balistics question diameter vs speed: please have data to back up statements

[Frosty]

Let me start by apologizing for asking this question; this topic has been beaten to death I know, but I've been searching for a very long time now and I'm tired of reading peoples opinions instead of data. Again, I apologize for the redundancy of this topic, but I hope that mine is at least a more specific question than most. With that said:


I've just recently purchased an XD45 Tactical, and I've been pondering its "man stopping power" relative to my 9mm and other rounds. In my searches I found a lot of comparisons of rounds such as the .40 S&W, .45 ACP, and 10mm. What specifically caught my attention was the 10mm round, one which I have never fired. Some seemed convinced that it is superior to the .40 and .45 because, if I'm not mistaken, it has a significantly higher muzzle velocity and ?energy?. I also recently fired a .44 Magnum revolver for the first time, and the owner claimed that, aside from the added FTF security inherent in a revolver, he wouldn't trust his life to anything else.


So to the point: I found myself asking whether or not having a load with such an excessive velocity was actually better in terms of transferring energy and/or momentum (I realize this won't translate directly into stopping power). From a physics standpoint, I feel like the best way to transfer the MAXIMUM amount of energy into a target (we'll ignore minor discrepancies in diameter for now) would be to have the bullet enter the flesh and stop just before exiting, be that achieved by hollow point expansion, lower velocity or whatever. So keeping all things equal, I feel like the .44 magnum would enter and exit an aggressor so fast that it's effects would be less perceived by the injured party than say a good expanding hollow point .45 that penetrated a full 12-14 inches and stopped just shy of exiting the flesh. I realize this assumes my attacker is not significantly overweight; again, I'm just discussing an idealized situation, you know, the one that is never encountered in real life .


I guess as an example of what I mean, I would use my shotgun. When I fire my 00 magnum loads at a wooden target stand, they go straight through and barely move the board, but when I use something small like a normal 2 3/4 birdshot, the wooden target is not penetrated, and the energy transferred is strong enough to shift the metal base in which the target sits. I realize this does not directly translate to what I am asking about pistol rounds, but you get the idea: rapid full penetration = minimal energy transferred.


So what are your thoughts? Please provide something to back up what your saying; "my friend said" and "common knowledge" are not sufficient support. Thanks a bunch fellow calgunners, and stay safe!


-Frosty

[zrock]

Dont go crazy over this stuff . find a handgun or a rifle that shoots well and be happy . Most of us work for a living and dont have time for this.

[spareparts]

Do some personal research and look at gelatin tests. They'll show you how rounds behave under ideal conditions.

[J-cat]

Frosty,

You have a good understanding what is happening when a bullet impacts. Keep in mind there are a myriad of hollow point bullets on the market. Some expand more readily than others. This is due to differences in bullet construction. Some have thicker jackets, harder lead alloy cores, smaller hollow points, lack creases in the jacket- all of which hinder expansion. 9mm/40/45 are defensive rounds. Their bullets are designed to expand rapidly and limit penetration. 44 Mag and similar are hunting rounds. Their bullets are designed to penetrate deep, hence less expansion and a tougher construction, generally speaking of course.

The 10mm does not enjoy the same popularity as the 9/40/45, so factory ammo selection is small, as is the ballistic gelatin data. The 10mm is loaded with bullets designed for the 40 S&W, but at a 200-300 FPS higher velocity. Buffalo Bore ammo loads the 180gr Gold Dot to 1350 FPS. At that velocity, the GD expands to over 1", some 30% larger than when fired from a 40, but penetrates the same or deeper.

So yes, the 10mm is significantly more powerful than the other three and can dump more energy in a human target. But a 45 ACP+P 230gr JHP at 1000 FPS is no joke either. Both make similar wounds in ballistic gelatin.

[CSDGuy]

Do some personal research and look at gelatin tests. They'll show you how rounds behave under ideal conditions.

No. It'll show how bullets compare under controlled conditions. Clothing, skin, flesh, and bone in real life conditions are hardly controlled. You take real world events with real world results and attempt to correlate real world performance with the gelatin results. This will at least give you some idea about what a given bullet's terminal ballistics will be.

As to loading to achieve an "excessive velocity", you'd have to be certain you're not exceeding maximum pressure. Also, bullets are designed for a specific performance within a certain velocity range. Exceed that and the bullet could very well fragment on impact (or in flight) and you might not get the penetration necessary, if you even hit the target...

Choose a quality manufacturer in a decent SD caliber (basically anything from about .38 Spl or .380 ACP on up) and you'll find that they all pretty much perform the same in gel testing. You might find that a full-house 10mm is too much for you to shoot well. Oh, and if you're going to shoot 10mm for SD, don't use FMJ. That's better for hunting... not as good for SD. (Overpenetration concerns)

[Frosty]

Do some personal research and look at gelatin tests. They'll show you how rounds behave under ideal conditions.

Unfortunately the only places I tend to find good links to ballistics gelatin tests are threads like this one I've just started. I've seen a good number, and any references would be appreciated, but I haven't really seen anything about the 10mm.

The 10mm is loaded with bullets designed for the 40 S&W, but at a 200-300 FPS higher velocity. Buffalo Bore ammo loads the 180gr Gold Dot to 1350 FPS. At that velocity, the GD expands to over 1", some 30% larger than when fired from a 40, but penetrates the same or deeper.

So yes, the 10mm is significantly more powerful than the other three and can dump more energy in a human target. But a 45 ACP+P 230gr JHP at 1000 FPS is no joke either. Both make similar wounds in ballistic gelatin.

So you're saying that a faster round, such as the 180gr Gold Dot in 10mm vs .40S&W, will not necessarily penetrate significantly deeper as much as it will expand more and more rapidly, allowing the bullets energy to be completely transferred just as it would at a lower speed? Of course this hinges on the fact that you've got a good expanding hollow point capable of doing so, but I'll give the benefit of the doubt to Gold Dot. I find your point interesting, and I appreciate your taking the time to run through this with me. I guess I was "idealizing" the concepts in my head a little too much and thinking that a bullet behaved more like a ball than a hollow point, which is clearly not the case for the majority of our choices for defensive rounds. Even so, I'm curious how the energies transferred compare between the higher velocity and greater mushrooming 10mm in the event of an in-and-out penetration and the slower and smaller expanding .40 that stops just shy of exiting the attacker.


From what I'm told, bullets that go in and out can be more lethal simply because they are damaging more tissue and giving you that many more opportunities to bleed out, which is usually the cause of death from handguns if I'm not mistaken. However, I've also been told that they are less likely to stop an attacker for the aforementioned reasons, hence my questioning the "energy transfer", which I am loosely associating with "stopping" or "knockdown power" (the latter I do not like).


Shoot if I had the time and money I might just get a high speed camera and some gelatin and figure this out myself.


Of course I'd never downplay the beloved .45 ACP. I do not regret my decision in calibers by any means, price being a big factor as far as frequent and effective practice is concerned; I hear 10mm can be quite pricey, even with .45 in such short supply. I really find 9mm more comfortable for myself personally in terms of control, double tap, and rapid fire (muzzle flip and rapid target reacquisition), but then again, I've only owned a 9mm (CZ 75B, that I LOVE), so with practice I hope to be as comfortable or more so with my new Springfield Armory XD45 Tactical. Not sure how I feel about placing my life in the hands of a gun that is single action only (vs my single double CZ), but that's a whole other topic.

[J-cat]

So you're saying that a faster round, such as the 180gr Gold Dot in 10mm vs .40S&W, will not necessarily penetrate significantly deeper as much as it will expand more and more rapidly, allowing the bullets energy to be completely transferred just as it would at a lower speed?

Yes. Whatever extra momentum the 10mm has is dissipated in additional expansion which reduces the bullet's sectional density and in turn limits the penetration. If you designed a 10mm Gold Dot and limited the expansion to say .650" just like a .40 S&W Gold Dot, the additional 300 FPS would cause additional penetration. That could be done by hardening the lead core, altering the jacket, etc.

A conventional JHP designed for the .40 S&W will prolly fragment at 10mm velocities and penetration will be drastically reduced.

In my opinion, an ideal bullet would shoot through and through and then drop harmlessly to the ground just inches past the target. That way you would get near 100% energy dump and two holes to blead out of. But there is no way this can be accomplished.

[J-cat]

Here is an interesting thread on another forum that you may appreciate:

http://www.thehighroad.org/showthread.php?t=269234

[Frosty]

In my opinion, an ideal bullet would shoot through and through and then drop harmlessly to the ground just inches past the target. That way you would get near 100% energy dump and two holes to blead out of. But there is no way this can be accomplished.

Time will tell; I could see an advent of "smart" bullets containing electronics in my lifetime . Hell, they've got a 12 gauge taser round (of course for LE only).

In the time since my last post I've been reading up a lot on effectiveness of depth of penetration vs (relative) diameter of expansion, as they are clearly going to be inversely proportional to some degree. It would seem that most believe that an effective 12"-15" penetration is significantly more important than good rapid expansion, which I feel would bode well for the 10mm in both regards. Not sure exactly how this bears on my topic, but probably worth mentioning.

[nn3453]

Good points, but when it comes down to it, evidence collected from people who have been in actual gunfights seem to indicate that what matters most if how well can you do under stress. Data is great, but that assumes that your experiment involves a perfect shooter (in most cases, a carefully aimed shot or a shot from rest into gelatin). In real life, that variable (the shooter) is the most important one.

All this stuff is great on paper, but can you execute a Bill Drill or any other practical drill under stress with the weapon and caliber of your choice? I'd take a 9mm over a 10mm any day because given my competence (or incompetence), I'd be more comfortable with fast aimed hits with a 9mm than 10mm misses. But then again, I keep a 45 and a shotgun loaded as my HD guns because I am fairly comfortable with both.

Let the discussion about data continue

[Frosty]

Good points, but when it comes down to it, evidence collected from people who have been in actual gunfights seem to indicate that what matters most if how well can you do under stress. Data is great, but that assumes that your experiment involves a perfect shooter (in most cases, a carefully aimed shot or a shot from rest into gelatin). In real life, that variable (the shooter) is the most important one.

All this stuff is great on paper, but can you execute a Bill Drill or any other practical drill under stress with the weapon and caliber of your choice? I'd take a 9mm over a 10mm any day because given my competence (or incompetence), I'd be more comfortable with fast aimed hits with a 9mm than 10mm misses. But then again, I keep a 45 and a shotgun loaded as my HD guns because I am fairly comfortable with both.

Let the discussion about data continue

Your point is, and will always be, one of the most valid in the discussion of home defense. I tried to be as thorough as possible in noting my assumptions and the idealized nature of my arguments, but yes, the data is really what I'm after. I too have a shotgun for home defense that I would certainly choose over either of my pistols: my Mossberg 500 18.5" with a Knoxx SpecOps Folder stock, loaded up with five 00 magnum shells (which in light of my recent research, I am reconsidering). Unfortunately I do have a fairly small residence and the likelihood of close quarters combat is high; having a longer weapon could be a liability, so given enough time I may attempt to acquire a handgun as a backup if my shotgun is compromised in a scuffle.

Thanks for keeping it concise, you probably just saved me from hearing the same from some more wordy members