armor vs ammo - known facts

[Marine Cpl]

You don't sound chilled. You sound vexxed. Come to PA. We will shoot naughty stuff. Or maybr we shoukd go to @Bullet Guy's and shoot really naughty stuff!

Perhaps words on a screen are translated or come off differently. I'm good, relaxed, and chilled. I'm watching TV with the Yorkie sleeping on my lap.

 

[meketrefe]

I created this thread to talk about real life applicable results.
I think between Hollywood and you-tube there is a lot of confusion already.
We know speed matters but we should also look at the reasons why
rounds are evolving and they are not 55gr fmjs anymore.
To that end there is a lot of scientific studies done.
We are not inventing anything here just talking.
Also if one wants to buy a type III AR500 body armor find out what brand
that guy was using and avoid it because no round should go through
regardless of angle, vibration or any other random factor.

 

[Podmonkey]

Perhaps words on a screen are translated or come off differently. I'm good, relaxed, and chilled. I'm watching TV with the Yorkie sleeping on my lap.

Thats true. In the real world I'm screaming at dispatch to find me a profitable run so I can make some goddamn money! I got guns n' ammo to buy damnit! And that spiffy rifle bag I bought wiped out my discretionary income, need moar!!

 

[Marine Cpl]

Will,
It is not about liking or not liking the results but about following some
method or something, it doesn't have to be too scientific but something that makes sense.
What is the point of a 55gr lake city shot from a 22 bolt action at 7 yards and
punching through some questionable type III body armor? It proves that speeds matters
like we already know but with the typical firearm and typical range it doesn't make a darn
difference.
The M193 nor the M855 where designed with that scenario in mind.
Let me give you an example on how ammo brand and batch make a big difference:
A 55gr FMJ from PMC is advertised at 3100fps from a 16" AR yet it comes out at 2800fps
measured with two of my cronos.
Same things happen with countless other ammo with the Lake City plant 55gr being the fastest
shooter from 20" AR and up. It also runs hotter than the average round.
So not all "green tips" brands have the same speed nor they should be tested for that purpose
as there are other rounds better suited for that purpose.
When you get to 16" AR the modern M885A1 closes the gap faster since it was optimized
for shorter barrels.
That is why I suggest to take a 55gr FMJ and comparing with a 62gr FMJ loaded at the
same pressure (oranges to oranges). The speeds are very similar and at only 75 yards
the 62gr comes on top in any test including armor or any other barrier. This w/o getting
into more sophisticated or complex tests.
Shooting M193 with a long bolt action at 7 yards is simply useless info.

What does that have to do with anything? Increase the thickness on the plate, shorten the barrel, get one 55 gr loaded with type X powder and a 62 gr loaded with the same type X powder and the faster 55 gr will make it through.

Now if you underload the 55 gr, the 62 gr will have more velocity but not enough to penetrate the same plate.

What the issue here. The only thing I'm saying that has been backed up by countless tests is that a lower, faster grain penetrates steel better.

 

[Podmonkey]

 

[Marine Cpl]

I created this thread to talk about real life applicable results.
I think between Hollywood and you-tube there is a lot of confusion already.
We know speed matters but we should also look at the reasons why
rounds are evolving and they are not 55gr fmjs anymore.
To that end there is a lot of scientific studies done.
We are not inventing anything here just talking.
Also if one wants to buy a type III AR500 body armor find out what brand
that guy was using and avoid it because no round should go through
regardless of angle, vibration or any other random factor.

They aren't 55 gr anymore because the 62 gr or the 70 grainers beat it for soft and medium barriers. I've said that already. There are more of those softer barriers than steel ones at 10 yards where a lower and faster grain will work better. It's a compromise. So that's why rounds of higher grains are being created.

It isn't evolving. That's like saying the 147 gr was an evolving to the 124. It isn't. The 147 gr will do better for soft tissue but not a harder barrier that needs speed.

 

[carpediem]

The thing I look at is not some numbers on a chart or theoretical events, but thins that are true and indisputable. Physics holds true regardless of caliber or target. In the second world war, the German Pzkpfw IV started out with a short barreled 75 mm gun. That worked fine until people began to up armor their vehicles. There arose a problem. The 75 no longer penetrated. Instead of altering the round, the first thing they did was to lengthen the barrel and give the round more velocity. It worked, and work was begun on improving the shells to deal with the ever increasing armor. The moral of this story is, velocity is king, until you can no longer extract any more velocity without destroying the projectile. If a 55 grain round penetrates xyz plate, and the heavier penetrator doesn't at x range, then to me, the penetrator is a no go. I wasn't looking to pierce plates at 500 yards. I was wondering about less than 100 yards. Against your standard AR500 plate as sold by Spartan or AR500. Not something as thick as the side of an M1a1. I was thinking of something a .308 could be necked down to to reliably penetrate given the cost to velocity by being gas actuated (AR). Even the early tank gewher rifles were huge cartridges driving small projectiles at high speed. They weren't super high tech projetiles in 1914.

 

[meketrefe]

Negative. The Vietnam era 55gr started as a perfect balance between grain and speed but specially because of the original
purpose to tumble upon impact. As the rate of twist got faster and rifles got shorter then the 55gr offers no advantage as
with heavier bullets also ballistics get better so they quickly catch up in speed.
As far as I know only one FMJ continues to tumble consistenly as designed that is the norinco 55gr but that is not as fast as lake city
and also surplus is very hard to find these days.
A 77gr is desired not for the extra energy withing 100 yards but because of the ballistics and extra energy at
long ranges.
Also there is no foreseeable practical scenario where the typical barrier at the typical range other popular ammo
could not be used with the additional benefits of better ballistics and extra grain.
I also have 62gr FMJ ammo that will do everything the 55gr does and a bit more.
Why buy 62gr FMJ vs 55gr FMJ? ..well, the 55gr is popular and well priced but when you find good 62gr fmj
the bullets provide almost the same speeds and more momentum therefore better performance in
any scenario.
for the advanced tactical folks they are going to look into specialty ammunition for the task at hand or like
the military use M855A1 that is our current service round. Or others are going to pack a 6.8spc that spits
85gr solid bullets at 3000+ fps from a short carbine.

 

[meketrefe]

The thing I look at is not some numbers on a chart or theoretical events, but thins that are true and indisputable. Physics holds true regardless of caliber or target. In the second world war, the German Pzkpfw IV started out with a short barreled 75 mm gun. That worked fine until people began to up armor their vehicles. There arose a problem. The 75 no longer penetrated. Instead of altering the round, the first thing they did was to lengthen the barrel and give the round more velocity. It worked, and work was begun on improving the shells to deal with the ever increasing armor. The moral of this story is, velocity is king, until you can no longer extract any more velocity without destroying the projectile. If a 55 grain round penetrates xyz plate, and the heavier penetrator doesn't at x range, then to me, the penetrator is a no go. I wasn't looking to pierce plates at 500 yards. I was wondering about less than 100 yards. Against your standard AR500 plate as sold by Spartan or AR500. Not something as thick as the side of an M1a1. I was thinking of something a .308 could be necked down to to reliably penetrate given the cost to velocity by being gas actuated (AR). Even the early tank gewher rifles were huge cartridges driving small projectiles at high speed. They weren't super high tech projetiles in 1914.

No 223 round penetrates a good quality type III AR500 body armor at any range from any rifle.
The 55gr at 7ft on from a bolt action and that plate (whatever that might be) means little regarding the practical effectiveness of the 55gr.
For every video of a 55gr making it through a "specific type of plate" at close range you will have 100 youtuber videos showing how it fails in quality plates and other hard targets.
The M855, Russian bi-metal and others are not "AP" rounds nor they were designed for that objective at any distance.
In 5.56 the best round will be a M855A1 or something similar aftermarket and even with all that will not defeat the quality armor.
You need 308 or 30-06 true AP rounds to drill through with authority at various ranges and as I originally stated.
We can discuss this all day and it will not change a thing.

 

[Marine Cpl]

Meke. Either you aren't understanding, or you do and are being a pain in the butt.

 

[meketrefe]

BTW since you mentioned the AR500 plate this is is a good quality setup.
They sell one they call it type III+ that will stop anything other than the true AP rounds.
Some hyper velocity rounds in stout enough bullets might go through too.
..or LM fmjs, BMG and such obviously.

 

[meketrefe]

Meke. Either you aren't understanding, or you do and are being a pain in the butt.

What if it is you who doesn't understand? Or that is never possible?

 

[Marine Cpl]

What if it is you who doesn't understand? Is that possible?

I understand. You are failing to. Google AR500 55 grain and see what you come up with. There are numerous instances where the 55 gr penetrate it. Why is that?

 

[Marine Cpl]

@meketrefe , watch this one. Even a 50 gr TSX made it through after the 62 gr failed to. Moral of the story, increase the speed to penetrate armor.

 

[spat]

I guess you don't like the results so now you come up with excuses. I thought you were above that unlike others on this forum.

One, He used the same barrel for both. So that was equal.

Two, It's obvious that the 55 gr was faster then the 62 gr. It doesn't matter if the 62 gr was a penetrator or not. It didn't make it due to being slower. Both were Xm Lake City rejects that you can buy.

Three. The range he shot it at for safety's sake makes no difference. That's the range that will be used when your door is kicked in. At 100 or 200, neither would have penetrated due to both rounds slowing down.

The point is that we don't know anything from that test except that *that* 55gr round beat *that* 62 gr round in *that* circumstance.

I could certainly load a 55 gr that is *slower* than a 62 gr if I wanted. A 115gr from a 9mm +p+ would certainly out penetrate a 90gr .380 in any test for instance. Even if you put those same components in a 9mm case and fired it from a 9mm pistol.....

To be a valid comparison of anything other than those 2 exact loads he needs to control all those variables.

 

[Marine Cpl]

The point is that we don't know anything from that test except that *that* 55gr round beat *that* 62 gr round in *that* circumstance.

I could certainly load a 55 gr that is *slower* than a 62 gr if I wanted. A 115gr from a 9mm +p+ would certainly out penetrate a 90gr .380 in any test for instance. Even if you put those same components in a 9mm case and fired it from a 9mm pistol.....

To be a valid comparison of anything other than those 2 exact loads he needs to control all those variables.

Watch the next video.

 

[spat]

I understand. You are failing to. Google AR500 55 grain and see what you come up with. There are numerous instances where the 55 gr penetrate it. Why is that?

I can get .22lr standard velocity to penetrate ar500 if it's thin enough.

All these videos are only valid for those specific conditions.

If I load 55gr and 62gr to the same velocity, the 62 will win every time.

If I load similar construction 55 and 62 grn to the same pressure, you will find a narrow window where the 55 outperforms. What % of need will be in that narrow window ?

If I load a 55gr fmj with a thin jacket vs a 62gr with a thick one to the same pressure it may not have any window where it is best.

 

[Cippee]

I'm gonna break this down by metal type first it 1.5" cold rold steel. This is stronger than hot rolled. Only shot it with black tip out of 300 mag. You can see how much it went through with the screwdriver.

 

[Marine Cpl]

If you watch the whole video, my argument about bullet construction, speed, and weight applies. That 50 gr TSX didn't do shit until he added 6 more inches of barrel to bring up the velocity and then it went through.

The 62 gr still couldn't make it through even with the 26 inch barrel because the velocity wasn't high enough.

 

[Cippee]

7075 alumium very strong aluminum. Stronger than most steels. It's basically what's used on Bradley's. The black tip went trough on one shot and the other was stopped because it hit at an angle. The plate was 1.25" the one that was stopped went through 1.5" before stopping. That's why they mount armor on tanks at an angle. The little chip (second pic) on the plate are 55 grain out a 16" ar-15.

 

[Cippee]

The 1/2" ar500 plate just exploded the steel core of the black tip and silver tip. The 55 grain did absolutely nothing to the plate. I think it would take a 50 bmg to get through 1/2". Look at how wide the divots are. You can see the core just shatters when it hits the plate.

 

[Cippee]

When I looked at the plate again it went through 1.75" of the 7075 aluminum so the plate is just a little weaker than the cold rold steel. Aluminium can get very strong in the right alloys.

 

[meketrefe]

I understand. You are failing to. Google AR500 55 grain and see what you come up with. There are numerous instances where the 55 gr penetrate it. Why is that?

Shitty plates maybe?

There are many makers from cheaper to more expensive plates.
like this one...

AR500 starts as hot rolled steel before treatment to acquire the desired brinell of 500.
When dealing with the cheapest AR500 there might be a break speed + bullet type but
nothing significant nor practical considering average rifles and ranges.

 

[Cippee]

Shitty plates maybe?

There are many makers from cheaper to more expensive plates.
like this one...

AR500 starts as hot rolled steel before treatment to acquire the desired brinell of 500.
When dealing with the cheapest AR500 there might be a break speed + bullet type but
nothing significant nor practical considering average rifles and ranges.

I agree the ar500 I have was incredible. It stopped the 155 and 162 grain ap rounds with no problem. Like I said they were out a win mag at 3400 fps. The 55 grain out the ar-15 didn't even chip the plate I'll post a up close pic of the impact.

 

[Cippee]

I'm pointing to the impact with the screwdriver. 55 or 62 grain is not going to even make ar500 break a sweat. There is no way it's going through.

 

[Marine Cpl]

Shitty plates maybe?

There are many makers from cheaper to more expensive plates.
like this one...

AR500 starts as hot rolled steel before treatment to acquire the desired brinell of 500.
When dealing with the cheapest AR500 there might be a break speed + bullet type but
nothing significant nor practical considering average rifles and ranges.

Stop focusing on the plate whether it's legit 500 or not. That isn't the point. The point is that if the 62gr cannot penetrate it (whatever plate that is) if it requires X amount of FPS, then if the 55 gr exceeds that velocity, I'll go through.

 

[Cippee]

As a welder ar500 does not start as hot rold steel. It's has other metals mixed it so it will respond to heat treating. Hot rold steel does not respond to heat treating. Ar500 has chromium mixed it as well as higher carbon.

 

[carpediem]

 

[Cippee]

That plate is only .25" thick.

 

[carpediem]

That plate is only .25" thick.

And that is the crux of my question. Standard body armor. Not two inches of cold rolled steel at 500 yards. Standard level III or III+ plates. A 22-250 at 4000 + fps and a 40 something grain hunting round defeated the plate. So body armor against a person armed with a 22-250 looks like a bad idea. If the guy is wearing a .5 thick plate, his odds improve, but a .5 plat is unlikely.