OK, my question is simple, but my reasoning is rather long, so please bear with me. Here is my question...
Is the .380 an adequate self-defense round, or am I kidding myself?
Let me see if I've got this right...
It seems to me most people feel ammo from 10 or more years ago was not yet developed to the point of offering reliable expansion, particularly through barriers. One needed mass to gain adequate penetration (whatever that is), and one needed speed to help ensure expansion. To gain speed, one needed to either lighten the load (resulting in less penetration) or go to more/different powder to gain more velocity. Too little mass and the round expanded but failed to penetrate. To much velocity and the round fragmented, each piece now having insufficient mass for penetration. This was perhaps the main reason many preferred the .45acp over the 9mm...a heavier round for penetration and it was already big, allowing for less need for expansion. Those who preferred the 9mm usually preferred more rounds delivered faster.
Enter the .40s&w. More mass (155 to 180 grains) compared to the 9mm yet moving at 9mm velocities. One had mass and speed, plus as an added benefit, the round was designed from the outset to be a modern hollow point, offering good expansion.
OK. Jump forward to today. Ammo manufacturers have refined bullet design and construction to allow for reliable expansion through barriers even at lower velocities (don't need +p anymore). If the data supplied from the manufacturers is accurate (and no, I don't believe most of what I read) modern ammo from 9mm and up offers reliable expansion at moderate velocities, and all achieve about the same level of penetration.
My college physics tells me that when a round expands more, the increase in frontal surface area will act as a "break", bleeding off velocity in much the same way as an opened parachute will slow a skydiver faster than an unopened parachute. So, while expansion allows for the bullet to hit more "stuff" as it passes through the target, it still requires the inertia given it by mass to keep moving and penetrate. A heavy bullet will have a given amount of inertia, and to slow this bullet to a stop takes energy from somewhere. This somewhere is the target. A lighter bullet has less inertia, and therefore it takes less energy from the target to slow it to a stop, causing it to penetrate less.
Bullets used to need velocity to expand, now they can trade high velocity for better design, but they still need mass to penetrate.
When I rely on a .380, I have been using the Corbon DPX. The velocity is really no better than any other .380 (out of my Keltec P3AT), yet it seems to expand well even through heavy barriers. That is good, and I will credit it to new design technology. My question... how does it achieve adequate penetration? It still weighs in on the light side of things (80gr), and an 80gr bullet has never been considered adequate for penetration. How is it that now it is enough? Mass doesn't get more efficient because it is new. Mass is what it is.
Am I kidding myself that my .380 is sufficient for self-defense just because it is a new design and has good gelatin numbers, or is my concern over the .380 unjustified, based on old ideas and old technology ammo?
I am a 9mm fan and I rely upon a 9mm when I can. I know there are 9mm's that are small (PM9/MK9), but there is nothing as small as my P3AT, and yes, size does matter. So, back to my question...Is a .380 an adequate self-defense round, or am I kidding myself?
moonshot
Is the .380 an adequate self-defense round, or am I kidding myself?
Let me see if I've got this right...
It seems to me most people feel ammo from 10 or more years ago was not yet developed to the point of offering reliable expansion, particularly through barriers. One needed mass to gain adequate penetration (whatever that is), and one needed speed to help ensure expansion. To gain speed, one needed to either lighten the load (resulting in less penetration) or go to more/different powder to gain more velocity. Too little mass and the round expanded but failed to penetrate. To much velocity and the round fragmented, each piece now having insufficient mass for penetration. This was perhaps the main reason many preferred the .45acp over the 9mm...a heavier round for penetration and it was already big, allowing for less need for expansion. Those who preferred the 9mm usually preferred more rounds delivered faster.
Enter the .40s&w. More mass (155 to 180 grains) compared to the 9mm yet moving at 9mm velocities. One had mass and speed, plus as an added benefit, the round was designed from the outset to be a modern hollow point, offering good expansion.
OK. Jump forward to today. Ammo manufacturers have refined bullet design and construction to allow for reliable expansion through barriers even at lower velocities (don't need +p anymore). If the data supplied from the manufacturers is accurate (and no, I don't believe most of what I read) modern ammo from 9mm and up offers reliable expansion at moderate velocities, and all achieve about the same level of penetration.
My college physics tells me that when a round expands more, the increase in frontal surface area will act as a "break", bleeding off velocity in much the same way as an opened parachute will slow a skydiver faster than an unopened parachute. So, while expansion allows for the bullet to hit more "stuff" as it passes through the target, it still requires the inertia given it by mass to keep moving and penetrate. A heavy bullet will have a given amount of inertia, and to slow this bullet to a stop takes energy from somewhere. This somewhere is the target. A lighter bullet has less inertia, and therefore it takes less energy from the target to slow it to a stop, causing it to penetrate less.
Bullets used to need velocity to expand, now they can trade high velocity for better design, but they still need mass to penetrate.
When I rely on a .380, I have been using the Corbon DPX. The velocity is really no better than any other .380 (out of my Keltec P3AT), yet it seems to expand well even through heavy barriers. That is good, and I will credit it to new design technology. My question... how does it achieve adequate penetration? It still weighs in on the light side of things (80gr), and an 80gr bullet has never been considered adequate for penetration. How is it that now it is enough? Mass doesn't get more efficient because it is new. Mass is what it is.
Am I kidding myself that my .380 is sufficient for self-defense just because it is a new design and has good gelatin numbers, or is my concern over the .380 unjustified, based on old ideas and old technology ammo?
I am a 9mm fan and I rely upon a 9mm when I can. I know there are 9mm's that are small (PM9/MK9), but there is nothing as small as my P3AT, and yes, size does matter. So, back to my question...Is a .380 an adequate self-defense round, or am I kidding myself?
moonshot