Found this neat video:
Interesting the .45ACP result or lack of it. The .357 would have been the worst hit so speed does more in some situations than big and heavy.
Yea that was interesting! Sledge Hammer! :o
Would've been cool to try that with some hard cast in the 357 or a 10mm. We found a vest like that about 10 years ago, and didn't find anything that would penetrate, but weren't shooting hard cast at the time.
Last year a friend brought a 3/8" sheet of carbon fiber to the gravel pit to shoot. 9mm, 40, and 45 FMJ all stopped in the carbon fiber (kind of weird, it would split into layers and trap the mushroomed bullet). The 10mm 6" barrel blew through it with JHP's and cast. The 45 ACP cast bullets also blew right through.
When looking at ballistic vest hits, it's 100% kinetic energy and area of dispersion. All the bullet energy is dumped on the vest, so penetration and momentum isn't the factor. That doesn't mean they can't hurt you. All bets are off, with a penetrating round. Larger bullets are easier to "capture", all else being equal, meaning the force is concentrated on an area relative to the bullet cross-section. I'd much rather be hit (wearing a vest) with a 230 gr. .45 at ~800 FPS, than any bullet weight (full power) .357, 9mm, .40, or 10mm. More energy, more concentrated. All of the force will impact the body, and a larger area (especially with less energy) is always much more desirable (or is that less undesirable....).
As DM1906 says, sectional density comes into play when considering penetrating barriers. The 357 mag has really good sectional density, and the case capacity to push small bullets fast.
A solid gold or uranium bullet in 10mm would probably blow right through that vest. Both are nearly twice as dense and lead, and would provide nearly twice the sectional density but have the same bearing surface. Not sure what the load data would look like though. :P
Quote from: DM1906 on August 12 2012 11:26:45 PM MDT
When looking at ballistic vest hits, it's 100% kinetic energy and area of dispersion. All the bullet energy is dumped on the vest, so penetration and momentum isn't the factor. That doesn't mean they can't hurt you. All bets are off, with a penetrating round. Larger bullets are easier to "capture", all else being equal,
Well, sort of... You're leaving out the part about what the bullet does when it impacts the armor. If it's a jacketed bullet, and mushrooms at all, it's acting like a larger caliber, and is easier stopped. Hardness of the projectile matters; that's why penetrator bullets are steel, tungsten, etc.
One thing to remember is the vest, as is worn on the body, acts to absorb and spread out energy from the impact. He tried to simulate this by using water bottles, but that is not the same. The fibers in the kelvar stretch pull and wad up, as it absorbs the energy decelerating the projectiles. Vest with "Hard plates" tend to deform/decrease eneryg/slow down/increase projectile diameter before it is captured by the kelvar weaves.
None the less the results were good at showing that the vest does a good job even if it is older/out dated... :o
Quote from: Yondering on August 13 2012 10:55:21 AM MDT
Quote from: DM1906 on August 12 2012 11:26:45 PM MDT
When looking at ballistic vest hits, it's 100% kinetic energy and area of dispersion. All the bullet energy is dumped on the vest, so penetration and momentum isn't the factor. That doesn't mean they can't hurt you. All bets are off, with a penetrating round. Larger bullets are easier to "capture", all else being equal,
Well, sort of... You're leaving out the part about what the bullet does when it impacts the armor. If it's a jacketed bullet, and mushrooms at all, it's acting like a larger caliber, and is easier stopped. Hardness of the projectile matters; that's why penetrator bullets are steel, tungsten, etc.
Well, sort of... I didn't leave anything out. That's how it works. The bullet "mushrooming" is a function of the ballistic material, and bullet design, and rarely do they ever expand much, if any, beyond their bore diameter, due to the ballistic material. Maybe on CSI. The bullet deceleration is what causes the mushroom, the base decelerating at a slower rate than the point, which is how the ballistic material works - rapid deceleration, and dispersion of energy. Otherwise, they vests wouldn't work. Hard cast bullets don't mushroom. FMJ bullets don't mushroom. Once removed from the material you could, theoretically, reload and shoot them again. Also take into consideration the material the bullet contacts before it meets the ballistic material. Low energy penetrators are designed to shear the ballistic material fabric, preventing the dispersion, and resulting deceleration. Rifles have more kinetic energy that can be absorbed by soft body armor, unless that armor is designed to do so. An LEO's soft body armor is very different than that of a combat soldier's. It isn't designed to prevent penetration of high energy projectiles. Steel/tungsten penetrator bullets are designed to penetrate trauma plates and heavier armor (such as other metals), which is why they are made of hard metal. The trauma plates in a vest, if used (they're usually removable), are designed to deform the projectile, aiding with the area of dispersion, while providing an initial deceleration. The most effective soft body armor bullets are actually tipped with a polymer-type compound. The original "cop killers" were a heavy gilding metal jacket, lead core, with a plastic-like point. Point being, a penetrating round of lesser energy must defeat the design, rather than merely muscle through it.
But, we weren't talking about high energy or penetrator rounds.
Quote from: DM1906 on August 13 2012 09:08:51 PM MDT
FMJ bullets don't mushroom. Once removed from the material you could, theoretically, reload and shoot them again.
That hasn't been my experience. Have you ever shot a ballistic vest with FMJ? I have. They mushroomed. Not like hitting a hard surface, but the frontal area did increase. The vest wasn't backed with any hard material either.
Quote from: Yondering on August 13 2012 10:59:23 PM MDT
Quote from: DM1906 on August 13 2012 09:08:51 PM MDT
FMJ bullets don't mushroom. Once removed from the material you could, theoretically, reload and shoot them again.
That hasn't been my experience. Have you ever shot a ballistic vest with FMJ? I have. They mushroomed. Not like hitting a hard surface, but the frontal area did increase. The vest wasn't backed with any hard material either.
I have (fired hundreds, if not thousands of FMJ and other bullet designs into ballistic vests/material, starting more than 20 years ago). I have only one original issue vest left, so I'm reluctant to blast it up for the sake of blasting it up. It's an antique, square panels (front/back, no side protection), elastic webbing (no Velcro). I have a couple later vests, but they are of modern design (Safariland, I think, pre Spectra), and I'll not likely sacrifice them. None of the FMJ's expanded beyond their bore diameter. None. "Mushroom" is a different story, and FMJ's don't mushroom. "Flattening" against a hard surface (such as a trauma plate), well that's different, and even so, nothing resembling a "mushroom". Every traditional bullet will deform against a harder surface. The "mushroom" you see in the movies and TV is NOTHING like reality (unless you mean reality TV). You don't just pick them out with a pocket knife.... They either fall out before you get there (from the other side, in very few cases), or you have to cut the material from around them. A FMJ bullet, of any handgun caliber/power, fired into ballistic soft body armor material, with a soft (human-like) support, will not "mushroom". TMJ's don't count, as they are not FMJ projectiles. TMJ's will typically deform, similar to soft lead, depending on the primary material, trauma plate, etc. If you've fired FMJ's into ballistic material, and they "mushroomed", you aren't hitting only ballistic material, or typical primary material. Did you measure the bullets, or only look at them?
Don't forget there are Expanding Full Metal Jacket bullets designed to expand twice plus their original diameters.
http://le.atk.com/pdf/EFMJBrochure.pdf (http://le.atk.com/pdf/EFMJBrochure.pdf)
http://greent.com/40Page/general/EFMJ.htm (http://greent.com/40Page/general/EFMJ.htm)
http://www.thegunzone.com/efmj.html (http://www.thegunzone.com/efmj.html)
Interesting video.
I read somewhere (I wish I could remember where) that one of the transit police agencies opted for the .357 Sig round due to the round's ability to penetrate through the train seat backs. The .45 had the least ability to penetrate, and the .40 came in somewhere in the middle just like in the video.
The .308 passed through so fast it wasn't able to dump any energy into the vest.
Quote from: DM1906 on August 14 2012 12:20:39 AM MDT
"Mushroom" is a different story, and FMJ's don't mushroom. "Flattening" against a hard surface (such as a trauma plate), well that's different, and even so, nothing resembling a "mushroom".
purely semantics, expanding/flattening/mushroom whatever.
Quote from: The_Shadow on August 14 2012 09:20:31 AM MDT
Don't forget there are Expanding Full Metal Jacket bullets designed to expand twice plus their original diameters.
http://le.atk.com/pdf/EFMJBrochure.pdf (http://le.atk.com/pdf/EFMJBrochure.pdf)
http://greent.com/40Page/general/EFMJ.htm (http://greent.com/40Page/general/EFMJ.htm)
http://www.thegunzone.com/efmj.html (http://www.thegunzone.com/efmj.html)
I've used some of those Federal EFMJ's in .40, they are pretty cool! The are the only round I've used that make a significantly larger-than-caliber hole in a thin piece of sheet metal; those EFMJ's seem to expand immediately on impact, and left huge holes.