M855 at 500 Y

[okie]

The question is will it penetrate SAPI and ESAPI.

Even an old delaminated SAPI plate is likely to take an entire magazine of M855 to get pass throughs. If I remember right, a SAPI plate can actually take an M2 AP without pass through but fails the back face deformation and therefore can't be level iv rated. Honestly, there's not much out there that's available to us civilian types that can defeat milspec armor, and for that matter I don't know if even M955 would do it or not.

The same can be said of almost any ceramic based commercial armor, as well, even the cheap brands. You can get ceramic plates for as little as a hundred dollars that will easily defeat almost any rifle round available on the commercial market. This is a growing problem because more and more criminals are turning up with body armor. It's something that hasn't historically been a problem in the past because armor used to be expensive and hard to find, and criminals were rarely confronted by armed victims. That dynamic has been flipped on its head over the last decade, though. Not only are more people armed than ever before, with better weapons than ever before, but now criminals can get extremely effective armor for next to nothing off of Wish. I expect in years to come that "armored robbers" will become the rule rather than the exception.

Now what M855 absolutely CAN defeat is polyethylene armor, which represents a massive market share of cheap commercial armor. One of the caveats to the cheap ceramic based armor is that it's extremely heavy, whereas you can get cheap, ultralight polyethylene armor for under a hundred dollars a plate. While there are a few polyethylene plates that can stop M855, they are around a thousand dollars a plate, so unlikely to be found on your run of the mill bad guy.

Unfortunately, though, almost all AR500 steel armor can easily defeat M855, so no help there. Outside of legit AP rounds, the only thing that can defeat AR500 is something going over about 3k FPS, namely a point blank hit from M193 from a 20 inch barrel. And unfortunately, the cheap, concealable nature of AR500 makes it perhaps the most common commercial armor you're likely to find out there. It's extremely heavy, but your average thug doesn't care about that. What can, however, defeat AR500 is M855A1, at least from a 16" barrel at close range. Hopefully that will become more available going forward, or something similar to it. It's not without its issues, though, besides its expense. It accelerates wear due to the high pressures, and you have to use a special magazine to get it to feed right, and those magazines are said to be garbage. The only ones available on the commercial market are from Center. Allegedly, the ones made by Okay are better, but they're unobtainium at least for right now. I have heard that the third gen pmags will feed M855A1, though, so if you managed to find some then maybe that's a viable solution.

[soulezoo]

Blackhawk Down guys should have been using 9mm so they could blow lungs out.

[rero360]

Even an old delaminated SAPI plate is likely to take an entire magazine of M855 to get pass throughs. If I remember right, a SAPI plate can actually take an M2 AP without pass through but fails the back face deformation and therefore can't be level iv rated. Honestly, there's not much out there that's available to us civilian types that can defeat milspec armor, and for that matter I don't know if even M955 would do it or not.

The same can be said of almost any ceramic based commercial armor, as well, even the cheap brands. You can get ceramic plates for as little as a hundred dollars that will easily defeat almost any rifle round available on the commercial market. This is a growing problem because more and more criminals are turning up with body armor. It's something that hasn't historically been a problem in the past because armor used to be expensive and hard to find, and criminals were rarely confronted by armed victims. That dynamic has been flipped on its head over the last decade, though. Not only are more people armed than ever before, with better weapons than ever before, but now criminals can get extremely effective armor for next to nothing off of Wish. I expect in years to come that "armored robbers" will become the rule rather than the exception.

Now what M855 absolutely CAN defeat is polyethylene armor, which represents a massive market share of cheap commercial armor. One of the caveats to the cheap ceramic based armor is that it's extremely heavy, whereas you can get cheap, ultralight polyethylene armor for under a hundred dollars a plate. While there are a few polyethylene plates that can stop M855, they are around a thousand dollars a plate, so unlikely to be found on your run of the mill bad guy.

Unfortunately, though, almost all AR500 steel armor can easily defeat M855, so no help there. Outside of legit AP rounds, the only thing that can defeat AR500 is something going over about 3k FPS, namely a point blank hit from M193 from a 20 inch barrel. And unfortunately, the cheap, concealable nature of AR500 makes it perhaps the most common commercial armor you're likely to find out there. It's extremely heavy, but your average thug doesn't care about that. What can, however, defeat AR500 is M855A1, at least from a 16" barrel at close range. Hopefully that will become more available going forward, or something similar to it. It's not without its issues, though, besides its expense. It accelerates wear due to the high pressures, and you have to use a special magazine to get it to feed right, and those magazines are said to be garbage. The only ones available on the commercial market are from Center. Allegedly, the ones made by Okay are better, but they're unobtainium at least for right now. I have heard that the third gen pmags will feed M855A1, though, so if you managed to find some then maybe that's a viable solution.

I never had any issues with M855A1 feeding from any magazines, ran it thru Gen 2 & 3 PMAGs, and issued mags with tan followers. The only issue I ever had was with either the M855A1 or MK262, shooting out of a really dirty and dry gun (was doing a torture test) popped a few primers and got a case stuck in the chamber.

[okie]

I never had any issues with M855A1 feeding from any magazines, ran it thru Gen 2 & 3 PMAGs, and issued mags with tan followers. The only issue I ever had was with either the M855A1 or MK262, shooting out of a really dirty and dry gun (was doing a torture test) popped a few primers and got a case stuck in the chamber.

Interesting. So it didn't chew up the feed ramp from the non EPMs?

[rero360]

Interesting. So it didn't chew up the feed ramp from the non EPMs?

Not that we noticed, during that deployment I only shot maybe 30 mags worth mixed between the two ammos in question along with some regular M855 from various manufacturers, mostly radway green. Being that this was from back in 2013, I can’t go back and look at the M4s for any wear and tear to them, but I can check the mags and see if there’s any damage to them, but I think they’re fine as I still use them regularly to this day, especially the PMAGs

[1168]

I routinely shoot M855a1 with a variety of mags, including green follower, tan follower, EPM, and M3. They all seem to work, although that does not mean that the newer ones aren’t better. I haven’t attempted to reproduce the study.

I’ve tested M855A1 against AR500 steel 5/8” targets, and they did not penetrate at 50yds. Didn’t seem close to penetrating. 16” barrel. I don’t know if this means anything about AR500 body armor, which I don’t recommend.

You mentioned bullets entering the shoulder and exiting inferiorly. In cases that I am familiar with, that occurred because the shootee was prone, and body armor doesn’t usually protect that specific entry.

[ABNAK]

I routinely shoot M855a1 with a variety of mags, including green follower, tan follower, EPM, and M3. They all seem to work, although that does not mean that the newer ones aren’t better. I haven’t attempted to reproduce the study.

I’ve tested M855A1 against AR500 steel 5/8” targets, and they did not penetrate at 50yds. Didn’t seem close to penetrating. 16” barrel. I don’t know if this means anything about AR500 body armor, which I don’t recommend.

You mentioned bullets entering the shoulder and exiting inferiorly. In cases that I am familiar with, that occurred because the shootee was prone, and body armor doesn’t usually protect that specific entry.

He may have been referencing the ages-old 5.56 myth.....shoot 'em in the hip and it comes out their shoulder. IIRC it originates from the early 60's DARPA reports from Vietnam, several years before the big U.S. buildup in 1965.

[WillBrink]

He may have been referencing the ages-old 5.56 myth.....shoot 'em in the hip and it comes out their shoulder. IIRC it originates from the early 60's DARPA reports from Vietnam, several years before the big U.S. buildup in 1965.

I thought it was shoot them in the hand and it came out their a$$?

[WillBrink]

He may have been referencing the ages-old 5.56 myth.....shoot 'em in the hip and it comes out their shoulder. IIRC it originates from the early 60's DARPA reports from Vietnam, several years before the big U.S. buildup in 1965.

I thought it was shoot them in the hand and it came out their a$$?

[okie]

He may have been referencing the ages-old 5.56 myth.....shoot 'em in the hip and it comes out their shoulder. IIRC it originates from the early 60's DARPA reports from Vietnam, several years before the big U.S. buildup in 1965.

The one I always hear is about .22 and how it's so deadly because it "bounces around."

Myths aside, though, surgeons routinely find bullets and fragments a long ways from their trajectory, in seemingly inexplicable ways. It's because the human body is a really tough sack full of lots of smaller, yet tougher sacks, and they're all highly elastic and slippery. When bullets start to slow down or fragment, it's kind of like hitting a patch of ice on a curve in your car while decelerating. Sudden, wild, and unpredictable changes in trajectory are par for the course.

So let's say you hit someone just an inch shy of their A zone. If the bullet fragments or causes a large enough stretch cavity to create permanent cavitation, the expectation among the general public seems to be that you have a pretty good chance of stopping that person. That either the stretch cavity will damage organs and vessels not in the bullet's direct path, or that fragments from it would pierce them. But the challenge to that notion is that the organs and vessels are simply displaced by the stretch cavity, and bounce right back into place unharmed. And fragments are likely to be diverted around organs and major vessels, causing them to fail at their intended purpose. So they might have a giant gaping wound in their chest a mere inch from their heart, and they might have hundreds of smaller ruptured blood vessels that will prove fatal, and they might have a chest full of fragments...but their heart, major vessels, and spine may all be relatively unharmed.

That's why I and many others disfavor anything that's designed to fragment. It takes surprising inertia to negate the effect of human physiology on bullet trajectory, so you don't want to intentionally remove inertia from your bullet on the very remote chance that one of those tiny little fragments might be the showstopper.

P.S. going back to the decelerating car analogy, consider that a bullet when it strikes a person decelerates from 1-3k fps to 0 fps in a matter of about 9 inches and a tiny fraction of a second. It doesn't take much of a "shove" to send that bullet off in a completely new direction, and it's inertia alone that enables it to overcome those little "shoves" as it passes through the various layers of a person's anatomy. It's even more stunning when you stop and think that at that point it's basically in a frictionless environment.

That same thing applies to fragments to a lesser but still very large extent. They are ejected from the projectile at very high velocity and decelerate to zero within just a tiny fraction of a second.