# Physics of an HP vs...



## Babbalou1956 (Sep 2, 2014)

Not sure how to title this but the question in, when a hollow point bullet mushrooms in tissue is it absorbing back some of the energy being transferred? It takes energy to fold back the petals. If they don't fold back, that energy goes to pushing the bullet through the tissue. Doesn't matter much if you're already dumping 300+ foot pounds of energy. But a 380 or 38 Special? Maybe. I've seen tests of the Underwood/LeHigh Xtreme Defense rounds & they make a decent impression for mouse gun rounds. Solid bullet with "fluid transfer" flutes. Bullet dumps all of it's energy into moving through the tissue, being a solid. Anyway, not something I lose sleep over. It's just something I'm simply curious about. How things work. I have to figure out stuff like this. Me, I won't buy the 380 Extreme Defense round because I'd prefer to shoot 50 rounds without fail before I trust it. That's about $100 worth of this ammo in 380. Nope, happy with my Gold Dots. I did get 2 boxes of LeHigh Extreme Penetrator years ago & they would not feed in my 380 Beretta Pico. Also tried Underwood standard pressure 38 Special Xtreme Defender & they were way hotter than any +P I've tried. Will save the rest for my 357 & keep using HST in the LCR.


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## AZdave (Oct 23, 2015)

In terms of energy transferred to the target it doesn’t matter. Or: the same weight (mass) hollow point transfers the identical energy as a round nose if the powder charge is the same. This assumes the bullet stays within the target.

A good test question would how much energy is transfered to target and how much energy is left in bullet after penetrating a foot thick target. This is an exercise left for the student. A better question is does energy matter if you don’t hit the target? So work ( energy times distance ) is more important.

The hollow point expands to create more damage than the round nose. So size does matter.


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## LostinTexas (Oct 1, 2018)

Energy matters because it moves things, drives things and breaks things. Energy "dump" especially from pistol rounds means little to nothing.
Expansion helps to ensure you don't hit BG A, Not BG B, and Not BG C. It also gives a little more surface area to do damage. That is about as good as a pistol caliber will get, at least for service rounds or the pocket calibers.
I'm not a 380 fan, and consider it a "Belly Gun", that is, put it in their belly and start shooting. The disproportionate stops the caliber enjoys are probably form this or at least contact distance. Yea that means you can touch the target. All pistol rounds are going to be best at these ranges, but I don't really want to have to get that close, even though I practice at these ranges, a lot.
Anyway all that for this. I researched a lot because my mother bought a 380 and got her Handgun License. THEN she asked for my help. A little cart before the horse, but OK. I did a lot of research and found the two best performing that I could for her. I found these two,
Hornady Custom, and Fiocchi Extrema
Both are about as good as 380 gets, expansion, penetration, and cutting edges. I would say to stay clear of the Boutique ammo, even from people like Underwood, but that is your choice.
You seem to be a little straying, but if you narrow down the question, better comments may follow.


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## Steve M1911A1 (Feb 6, 2008)

This note isn't about the .380, but rather about the transfer of energy:

So-called "stopping power" is the result of the "energy dump," the transfer of all of its energy, from a bullet which stops within its intended "target."
Bullets which pass on through don't leave much energy behind. And light bullets which travel slowly also don't deliver much energy, even when they stay in there.

The transfer-of-energy problem used to be solved by shooting big, heavy bullets which travelled slowly. This was especially true of the military requirement for non-expanding projectiles.
This specific part of the transfer-of-energy problem is what caused our switch from .38 Colt and .38 S&W, to .45 "Long" Colt and .45 ACP, during the Philippine insurrection.
(Remember that .45 ACP ballistics were designed to equal those of the .45 "Long" Colt.)

This changed when engineers began to design better bullets.
Now, expansion became more important than mere bullet diameter, and higher velocity became equally as important as greater mass.
(Indeed, it might be said that when much better bullets came along, higher velocity became _more_ important than bullet mass.)

This is why, nowadays, the 9mm Parabellum pistol cartridge is able to be the equal of the .45 ACP pistol cartridge, and the .357 Magnum can deliver all of its energy to its "target."
Better bullet design has elevated the .38 Special's effectiveness, and it has made the .380 into a fairly effective defense cartridge (if you place your hits carefully).


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## berettatoter (Sep 1, 2011)

Well, I don't feel under gunned with a .38 or .380 Auto. A friend of mine was killed with a .38 Special LRN, out of a snubby...at about twelve feet. One shot, right through the Sternum, went right through his heart. 

Just like Steve said, shot placement trumps caliber or bullet design. If you can achieve this with a big and heavy bullet, all the better.


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## pic (Nov 14, 2009)

In layman s terms, its engineered to expand and equalize a larger caliber bullet.


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## pic (Nov 14, 2009)

Steves right about the energy being transferred into the body

Many variables come to mind
Energy transfer made the 45 very popular, its all energy at a slower ft per sec , all hard ball. Feeding Reliability was a concern. 
To much penetration, the energy gets away from the intended target.
As a 357 would. (UP close ) 

if you're hunting scoped out at 100 feet. The penetration could use the 357 velocity


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## pic (Nov 14, 2009)

The tommy guns were all hard ball ammo


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## denner12 (Oct 14, 2017)

Babbalou1956 said:


> when a hollow point bullet mushrooms in tissue *is it absorbing back some of the energy being transferred?*


No. It's just losing energy in the target/transferee, nothing absorbs back. At least I don't think so?


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## pic (Nov 14, 2009)

denner12 said:


> No. It's just losing energy in the target/transferee, nothing absorbs back. At least I don't think so?


Absolutely I agree. Only thing you would lose in my opinion is velocity if the bullet expanded before hitting the target. Thinking ( scratching head) lol


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## LostinTexas (Oct 1, 2018)

pic said:


> The tommy guns were all hard ball ammo


45 ACP in .mil ball ammo enjoys a legendary reputation, and for much of it, an earned one.
A few things to note.
45 ACP is a large slow round that will yaw somewhat predictably and quickly(ish). This make it a very unique offering and lends to a lot of the success.
Not many round nosed rounds are desirable, but the 45 is at least adequate. 
The 45 was popular when not much else was out there. The modern, or even older style HP ammo wasn't very good, popular, or even available during the hay days. SP wasn't used in auto loaders, or for much else at the time. The service calibers, for lack of a better description, sucked. Anemic, and not too reliable. 
38SP one of the most anemic calibers out there today, was the best thing going for it's day. For some reason the 44 SP, 45 Colt, and even 357 weren't that popular, although in the mid 30's and early 40's it was still new. It became legendary, and still is.
The legendary performance and the reality of performance for the 45 has quite the gray area.


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## pic (Nov 14, 2009)

I still believe knockdown power is a legitimate term . Common sense tells me so.
45 cal is a great knockdown round, it has knockdown capabilities as other rounds also possess. 
I twisted the main conversation here a bit, sorry


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