Quote:
Originally Posted by cbtengr
Thanks for all the feedback, I got a box of WIN JHP's and did a little backyard shooting the other day. The rounds all cycled perfectly which did not surprise me as they are very much round nosed like the FMJ rounds. From 20' both FMJ and JHP's penetrated a pine 2X4 but not a 2- 2X4's. Not being any sort of authority on ammunition I am surmising that the JHP's create more damage to human flesh than to a 2X4. Its strictly for self defense in the home.
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Terminal ballistics discussion follows. Remember that there are exceptions to every rule, and that an elephant has been killed with a .22 Short, so anything can happen.
Normally, given the same velocities and bullet weights, expansion of a bullet is a direct opposite of penetration. Increased expansion reduces penetration.
Most people assume that pushing an expanding bullet faster (more velocity) means more penetration and slowing it down means less. That is incorrect. Maximum penetration is normally from a FMJ or an unexpanded bullet.
Expanding bullets (jacketed hollow points, jacketed soft points, etc.) are designed and constructed to function within a specific velocity range of a few hundred fps and at relatively short ranges. For most pistol bullets, that is going to be between 700 and 1400 fps, with the largest portion (minus 9mm and magnums) being subsonic. Most handgun bullets are not fast enough to create much temporary cavitation.
If you push an expanding bullet faster than it is designed to function, you get less penetration and more expansion or fragmentation. If it is slower than designed for (for example, a shorter barrel or longer range to the target), the bullet may penetrate deeper and not expand as much, if at all.
A bullet needs to penetrate deeply enough to reach vital organs and damage them. Expansion, as with a hollow point or soft point, creates a larger permanent wound channel as the bullet gets physically larger and crushes more tissue. Most organs are only a couple of inches from the surface, if you are shooting the side closest to the surface. Unfortunately, live targets move and do not always present themselves optimally for your shooting. You may have an angled shot or a shot through an extremity that requires 12" - 14" to reach vital organs like the heart, lungs, large vascular structures, etc. Excessive penetration is not normally a good thing, in that you do not want your bullet to penetrate a target and continue winging its way downrange looking for additional targets of opportunity like family, friends, innocent bystanders, etc. For those reasons, reliability is primary, penetration is secondary (up to the 14" mark or so), and expansion is tertiary.
Bullets that come apart too soon are creating shallow surface wounds that may not be incapacitating or even fatal. Bullets (especially small ones) that penetrate too deeply without expanding or fragmenting may require several good hits to cause enough damage to incapacitate the target. Everything is a tradeoff.
Wounds that cause an armed assailant to expire after the fight is over may represent a Pyrrhic victory, but will be scant consolation if the target is not incapacitated before inflicting serious injury to yourself or those you are trying to protect.
The requirement to simultaneously penetrate and produce controlled expansion has led to bonded bullets, which allow for the jacket to remain attached to the core of the bullet after expansion and continue to penetrate together. The longer the expanding bullet retains its jacket, the further it will penetrate due to the jacket being harder and less subject to deformation than its lead core. Shooting through cars, glass, light construction, heavy clothing, etc. drove this development. The technology is not fully mature, and some bonded bullets may be less likely to expand than non-bonded bullets, but they shoudl penetrate better.
If the handgun rounds feed and function 100% of the time in your weapon, and penetrate adequately, the one that expands to the maximum diameter and destroys the most tissue is the better one.
Wood is a poor substitute for tissue in ballistic testing, thought it has been used in the past for penetration testing. The easiest way to test penetration and expansion at home is to either get some meat, like a large roast, or shoot into water, like gallon jugs or zip-locs if you want to see expansion in a perfect world (no bones, tendons, etc.) Drape it with clothing if you want to simulate the real world performance somewhat better. I would expect a .380 ACP JHP to stop in a few gallons of water, but I would set up five or six just to be safe, and have a good backstop to be sure. You can measure the penetration and the expansion, and weigh it to determine the retained weight when expended.
A .380 ACP is a compromise and has difficulty making the penetration requirement even in FMJ form. Robbing energy to create expansion with a JHP cuts that even further. The .380 is not necessarily a bad choice, on occasion, I carry a .380. You just have to understand that it is a compromise fight stopper and it is up to you to put the bullets where they count, and possibly more of them to achieve rapid incapacitation.
Not preaching here, just trying to explain how bullets work. There are better and longer explanations elsewhere, if you would like to know more.
TR