Ideal Caliber and Ammunition for Optimal Wound Cavity, Energy Transfer, and Internal


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MashieNiblick
July 21, 2011, 10:59 PM
Take a look at the video at the bottom of the page of the following link:
- http://www.hornady.com/store/380-Auto-90-gr-Critical-Defense/

The video is of a 90gr 9mm diameter hollow tip penetrating through a layer of FBI down.

Hornady states 1000 ft/s for this round out of a 4" barrel.

In the video, the bullet exhibited a 6" major wound cavity with total penetration = 10".

It further stated that typical HP rounds would plug, act as an FMJ, penetrate entirely through target with minimal expansion, and thus, only a small percentage of the bullet's potential energy would be transferred to the target.


Another point: i believe, correct me if i am wrong, that a bullet's expansion is to a large extent proportional to the bullet's deceleration when within target.


Which gets me to thinkin' (again, correct me if i am wrong). . .:
- A full house .357 magnum round, 125gr, at 1450 ft/s, through an identical length 4" barrel, would:
-- Overpenetrate the target
-- Have minimal expansion due to the conservation of its momentum as a product of its increased mass,
therefore
-- the energy transferred to the human target by the full house .357 magnum would be less than that of the .380, the wound cavity would be less ideal, and the internal tissue damage would be less severe


Good thing Hornady modifies its bullets' designs with relation to optimal expansion to accomodate the different bullet weights and calibers- .380, .38 special, .38 special + P, and 9mm.


I'll still fire my full house rounds at the local range for effect, and carry them within my revolvers just in case i need to penetrate something in front of the cowardly perps we have here locally.



Cheers!
- MN
:D

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357 Terms
July 22, 2011, 04:58 AM
At 1450fps...it will expand, and tranfer all the energy. Is 380 all that you can carry?

jad0110
July 22, 2011, 07:34 AM
Actually, if anything the stronger 125 grain and lighter .357 Magnums traveling at least 1400 fps tend to under penetrate; the higher velocity tends to open up the HP rather quickly, limiting penetration more than heavier, slower (158 grn for instance) .357 loads.

Energy transfer does not matter, not until you get into say the 60 mm mortar range. The ratio of bullet mass/velocity to the mass of a human being is rather tiny and insignificant (especially with handguns). Temporary cavity at nearly all handgun velocities doesn't exist. The only thing than can be relied on is the permanent cavity/crushing effect of the bullet itself. And we are of course ignoring psychological effects of a firefight on both the BG and the defender, probably the most important consideration of all.

So in the end its all about picking a platform that you'll actually bring with you where ever you can take it legally, then pick the optimal caliber (if there is a choice) for your priorities (consider ammo cost, recoil, noise, capacity tradeoffs when applicable, ammo selection and availability, etc). If you can, choose a caliber and projectile combo with adequate penetration (you determine the threshold, most go with the 12" FBI minimum) with the possibility of expansion as a bonus.

GRIZ22
July 22, 2011, 11:23 AM
if anything the stronger 125 grain and lighter .357 Magnums traveling at least 1400 fps tend to under penetrate; the higher velocity tends to open up the HP rather quickly,

Something I read is the best example I know of supporting this statement. A large police dept switched from using 125 gr 357s from a certain manufacturer to the same manufacturer's 38 special load. Both used the same bullet. Using the 357 they never had a bullet exit a body and the 38 always exited the body.

32 Magnum
July 22, 2011, 11:47 AM
Individual bullets intended for "self defense" (i.e. shooting humans) are engineered to expand to meet the FBI standards. The designers spend a lot of time developing jacket strengths, skiving, core material alloys, depth and diameter of cavity, etc. to ensure that their design works within the set parameters. If you were to take samples of all the major manufacturers' SD bullets and examine their construction and composition, you would find that there are similarities but also differences in how they accomplish their goals.

MashieNiblick
July 22, 2011, 12:17 PM
So a 1450 ft/s 125gr .357 mag round will expand much more than a-

1000 ft/s 90gr .380 round

even though they are of an identical diameter?

That's why the .380 will penetrate 10" ballistic gel,

as will the .357 mag? ? ?


Thank you in advance,
- MN

gamestalker
July 22, 2011, 04:47 PM
I'm a reloader and thus experiement often with various loads and bullets. I fill a box that is 18" from side to side and line it with a plastic trach bag and then fill it with water and tightly rolled up denim. I tested the .357, 9mm, and .40 in this manner and was really surprised. The .357 with 125 gr. XTP and Gold Dots pushing 1400 fps 125 grs. went through and through but made a really big wound cavity. The bullets which I recovered in a soft back stop were completely expanded and really consistently.
The 9mm did well also with a 115 gr. @ almost 1400 fps but didn't display a wound cavity that suggested it expanded fully until nearly all the way through. But it did at least fully expand at some point.
The .40 was simular to the 9mm except it had a very limited degree of expansion using a 155 gr. XTP. But it was only pushing just over 1200 fps which was probably what limited the expansion to that extent.

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