Bullets into pancakes: Has expansion gone too far?

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Wapato

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When considering different types of ammunition I'd look at those charts showing penetration and expansion, like I suspect many people do, with more expansion being better all other factors being equal.

However I was reading on article on the 357 SIG that had the attached picture of a Cor-Bon round, and it struck me just how much of a pancake that thing had turned into. When I'd thought about expansion, I imagined a wider bullet front, with jagged spinning petal blades pulverizing a jagged hole through a target.

However with such a pancaked bullet I could easily imagine it turning sideways. If it oreignted to present the least forward surface area, what would that be? For that example I'd guess less than the area of the unexpanded bullet.

So is that happening? That made me think of the other attached pic, which I believe I actually got from this forum. The thing to note is that you're looking in from the side, but you can count the petals on a number of those rounds. They have indeed turned sideways.

So are these modern expanding rounds dumping all their energy at shallow depths, and then getting their penetration numbers by going on a low speed sideways glide out past the desired twelve inch mark? What affect would that have? Are companies designing less effective rounds so they can look more impresive when reviewers fire a few rounds into gelatin and post the results?
 

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What difference would it make. As long as you are getting the penetration and making a hole at least 1/2" in diameter the bullet is working just fine.
 
However with such a pancaked bullet I could easily imagine it turning sideways.
Click to expand...

Here are some YouTube videos by a guy named BrassFetcher.

They are ultra slow motion video of various handgun bullets shot into translucent ballistics gel. I've chosen these clips from his many, many videos to show that yes the bullets in these selected videos turned, but they turned after they penetrated to their maximum depth, and the gel sucks them back again.

I wouldn't worry too much about those images in your post with the bullets turned sideways.

http://www.youtube.com/watch?v=MEQOiEPMJ9U

http://www.youtube.com/watch?v=y0fr2By2qus
 
I think they keep enough momentum to stay forward facing.

But it's why I like heavier for caliber bullets, allows a lot of expansion without negatively affecting penetration as much.
 
hAkron said:
That picture is quite a sales pitch for the 230gr .45 ACP
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Watching the videos on Brass Fetcher, the higher-velocity 200-grain Speer Gold Dot dramatically outperformed the 230-grain version of the same bullet. The difference in the shockwave was very impressive.

230-grain: http://www.youtube.com/watch?v=d2taJFU1vG8

200-grain: http://www.youtube.com/watch?v=A8XqAMn4Wqo

I'd definitely choose the 200-grain bullet here. No question. I've done some video comparison. The 9mm Speer Gold Dot outperforms the 230-grain .45 ACP in terms of hydrostatic shock, but the 200-grain .45 ACP Gold Dot blows it away. One thing I've noticed is that velocity is king when it comes to hydrostatic shock. Reducing bullet weight for increased velocity is almost always worth it. You get similar penetration and much more destruction.
 
Wapato said:
However with such a pancaked bullet I could easily imagine it turning sideways. If it oreignted to present the least forward surface area, what would that be? For that example I'd guess less than the area of the unexpanded bullet.
Click to expand...

In fluids of high density and viscosity (much greater than air), oblate (flattened, not pointy) objects tend to find their greatest stabilty in flight- think of the shape of a submarine, blunt at the front, tapering to a point at the rear of the vessel.

Wapato said:
So is that happening? That made me think of the other attached pic, which I believe I actually got from this forum. The thing to note is that you're looking in from the side, but you can count the petals on a number of those rounds. They have indeed turned sideways.
Click to expand...

As such objects slow down in high density, high viscosity (as opposed to air) fluids, they can become destabilized more easily- sometimes expanded JHPs do so (reorient) near the end of their track.
 
Judging bullet performance by firing into gelatin is a little like determining how a car will perform on the street by its fastest lap time at Talledega. A bullet that expands perfectly in gelatin may not do the same thing in a human body. Properly calibrated ballistic gelatin approximates human muscle tissue. If we were made up entirely of muscle, it might mean something...but we're not.

Gelatin, like any other test medium, is useful mainly in comparing different bullets and calibers.
 
I feel like calling Shennanigans on the .45acp track. It looks like it was manipulated after the fact. Does anyone else see it? :confused:
 
I was hoping to see some pancake shooting in this thread!

That .45 pic above does look very strange.
 
1911Tuner said:
Judging bullet performance by firing into gelatin is a little like determining how a car will perform on the street by its fastest lap time at Talledega. A bullet that expands perfectly in gelatin may not do the same thing in a human body. Properly calibrated ballistic gelatin approximates human muscle tissue. If we were made up entirely of muscle, it might mean something...but we're not.

Gelatin, like any other test medium, is useful mainly in comparing different bullets and calibers.
Click to expand...
I'd say it's more like a crash safety test than a lap on the track. You simulate the conditions of an accident, but you are using dummies and taking measurements to assess injuries, rather than using live humans. There's nothing wrong with such tests, but take them for what they're worth.

What bothers me more about images like the one posted above is that each caliber's performance is represented with a sample size of 1. What would be more meaningful is how, on average, 1000 or 10,000 JHP 9mm bullets performed in ballistics gelatin, 10,000 45acp bullets performed in ballistics gelatin, etc. From that sort of data, you could actually start to ascertain a meaningful measure of average penetration, expansion, etc. Testing a single bullet tells you something, but it doesn't tell you the whole story.
 
Yep. That's a pretty well-worn humorous image. I believe it may be based on this, which may or may not be accurate:

Handgun_gel_comparison.jpg
 
The reality is that people and animals are made of bone and tissues of differing densities.
Rounds also deal with clothing and other materials that reduce perfect transfer of hydrodynamic forces that push the petal outward and are used for expansion.

The round that hit a bone not long after impact and has some petals bent and deformed is not going to actually expand in the designed way with the petals uniformly peeling away. Instead expansion of some petals is going to be hampered, and others may still peel back somewhat. Since most shots are going to contact bone fairly soon, most results will be different than in ballistic gelatin.


Gelatin and similarly shots into water jugs and other entirely uniform fluid mediums give a visual result that is well beyond reality.
If targets really were uniform mediums that would uniformly apply hydrodynamic pressure to the frontal surface of the bullet then designing the perfect bullet would be a lot easier.

In fact it is possible to make a bullet that would sacrifice some effectiveness in real tissue to give even more impressive visual results in gelatin. You can make a more fragile bullet that depends more on the shape of each petal to maximize expansion or create a cool wicked looking shape. While in real shootings the increased reliance on a more delicate petal shape to that achieves that perfect visual result will often be bent prior to expansion when impacting bone in real targets and that will reduce its overall performance.
While another round designed to better resist such impact and still give decent expansion won't have the perfect shape to give the most impressive gelatin demonstration in a uniform medium, even if it performs better in real life.



Bullets will generally expand much better in the uniform mediums like gelatin than they would in real life against something that deforms the bullet somewhat with bone impacts and less uniform tissue distance travelled.
This means you can see what it does in gelatin, and expect it to not quite do that much in real tissue.
It is a comparison more than what should be expected in actual performance.
The bullet that turns itself almost inside out in gelatin may be only expanded half that much in an actual target. With the petals not pointing outwards so nicely after they were deformed by bone early on, and some failing to open much at all. That deformation and change in shape is going to result in a very different wound tract than in gelatin.
 
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I imagined a wider bullet front, with jagged spinning petal blades pulverizing a jagged hole through a target.
Click to expand...

Handgun twist rates are not that high.

Keep in mind it is turns per inch.

A one turn in 7 inch barrel is going to make one turn through 7 inches of tissue also.
 
First of all solid replies in this thread. Thanks for the "origional" of that one picture I got from here.

Though I'd be careful to avoid a calibre discussion.

F-111 John said:
Here are some YouTube videos by a guy named BrassFetcher.

They are ultra slow motion video of various handgun bullets shot into translucent ballistics gel. I've chosen these clips from his many, many videos to show that yes the bullets in these selected videos turned, but they turned after they penetrated to their maximum depth, and the gel sucks them back again.
Click to expand...

Thanks for that. Although as examples go those are relatively slow rounds and they don't really pancake. They take a more mushroom shape with an expanded head but retain a significant "stem".

But when I get some time I'll poke around there and see if the guy has some rounds that really pancake. I could see them managing to keep their orientation.

GLOOB said:
If it turned sideways... so?

http://www.american-indian-art.com/Beaded-16b.JPG
Click to expand...

The reason for expanding bullets in the first place is increased cross section to produce a bigger hole and/or transfer more energy to the target. If you're dumping all your energy at the surface and once you get into vital regions you actually have a lower surface area and a transfering less energy than you might do better with a much cheaper non expanding bullet.
 
As long as it provides adequate penetration (enough to reach vital organs and vessels), without over-penetrating the target, expansion is just icing on the cake.
 
If you haven't picked up a bullet that has hit a steel plate -- round nose or HP makes no difference, All the bullet's energy was expended instantaneously. Imagine a penny run over by a locomotive wheel.

The gel is used as a gage for bullets, to see how bullets expend their energy in a standardized consistent medium. If they expand and stay together while expending their energy, they cause more medium damage.

Changing the medium changes the results.
 
First, hydrostatic shock is a phenomena that requires, according to Fackler, a minimum of 2000fps.

Then, there is the fact that Hydrostatic Shock has as many definitions as anything else. See:

http://guns.wikia.com/wiki/Hydrostatic_shock

Another small item is that most handguns have quite slow rifling. Even the .45 ACP uses a 1:16 ratio. 1:7 is actually quite fast.

Gelatin can be rigged to show pressure waves caused by bullet impact to it. Are they considered hydrostatic shock? maybe, but that depends on how you define it. The exact same pressure wave could be measured by hitting it with a baseball bat. Hardly what one considers hydrostatic shock.

Expansion in gelatin, as has been repeatedly mentioned, is NOT expansion in human bodies. The best possible correlation is the minimum depth and maximum expansion INDICATE what they MIGHT do when used in dynamic situations and hits are made upon humans. Rarely, does the bullet penetrate, or expand, as well in a human as in the gelatin.

So, the short answer would be that the more expansion, and penetration to a desired depth, that you have in gelatin, the better chance you have for satisfactory bullet performance against human targets. While that may sound harsh, we need to face the facts that JHP bullets are designed for use against humans, FIRST and FOREMOST. :rolleyes:
 
These.images.show one round and you guys are arguing over the results. In a real world situation I am firing more than once with each round inflicting more damage. If I keep a tight group it will multiply the hydrostatic damage by hits in an already damaged area. This is one of those subjects that really have no major significannce in a dark alley with a bad guy.
 
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