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Hi everyone, first post here :)

 

I stumbled across this video

 

 

 

It’s super dense polyethylene with a neutral buoyancy core for impact resistance. It weights only 4 pounds, so for weight effiency it’s around 3 times better than ar550 and 4 times better than other ceramics ballistic plates, AND that’s while including the water, which I doubt add any bulletproof capabilities. 

 

Is it just me or does it sound a bit fishy?

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Well  it's UHMWPE so I don't think it's subject to plugging the way a steel plate would be.  It's also a lead core rather than something harder which I think affects penetration..   Also there's ballistic limit - stopping a single round of a single type/weight at a given velocity is great, but how repeatable is that fact?  Can it stop such a round 50% of the time  (v50) or almost every time (V0)?    There's also the backface deformation (hard to judge but at least 25-30mm?).  And a 4lb plate hit by a 750 grain round moving at 2400 fps is going to impart considerable energy and momentum to the body which isn't likely to be any kinder (ESPECIALLY with the aforementioned backface deformation.) 

 

Reminds me of some of the claims you used to hear about Dragon Skin.  There was a similar 'test' done for something called Kryon Terminator some years back which also claimed to stop .50 cal (though it was unclear whether that had any relevance to body armor.)  It's entirely possible, but with body armor there's always more to it than 'can it stop X round' (again Dragon Skin.)

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The water might do something.  In tanks there are armor arrays that double as fuel tanks (or are they fuel tanks that double as armor arrays?) where the diesel fuel is arranged in a container such that it will create pressure waves that are disruptive to threats that penetrate the fuel tank.

It is my understanding that this trick has to be tuned to a specific threat, with array performance falling off the less similar the threat is to what it's designed for.

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DT9NsRz.jpg

O4qq2p6.jpg

^10 meters

 

there was a tests with  polyethylene, for buletproof vests, it was able to stop AKM 7,62x39 point blank(10 meters), but when bullet velocity drops to distance of 300 meters , bullet went through 

d3bqkFM.jpg

 

300 meters^

don't know if it was problem with certain polyethylene or it correct for any sort of polyethylene

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Doesn't work for me either.

 

I'd like to see how the energy is dissipated. The bulge on the reverse side suggests that it's still pretty concentrated, which would be pretty bad news for one's internal organs anyway...

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18 hours ago, Wiedzmin said:

updated 

Thanks.

 

Having seen the images now, all I can say is that that's a very thick sheet of UHMPWE - in the order of 25-30mm which gives it an areal density of 23.6-28.3kg/m^2.  It's still a huge saving over an equivalently-protective steel plate (47.1kg/m^2 for a 6mm plate) though.

 

I suspect that this sort of thing works best as a backing for a hardened strike face, as it seems to need a certain level of bullet deformation to work properly. Which probably argues for something more along the lines of a 1.5mm hardened steel/4mm ceramic plate up front, backed with a 15-20mm sheet of UHMPWE, as your optimum. 

 

Edit: after thinking for a bit, I remembered that you'd probably want to put any ceramic elements about 1/5 to 1/3 of the way in to maximise their efficiency.

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On ‎7‎/‎25‎/‎2018 at 12:36 AM, SirFlamenco said:

Hi everyone, first post here :)

 

I stumbled across this video

 

 

 

It’s super dense polyethylene with a neutral buoyancy core for impact resistance. It weights only 4 pounds, so for weight effiency it’s around 3 times better than ar550 and 4 times better than other ceramics ballistic plates, AND that’s while including the water, which I doubt add any bulletproof capabilities. 

 

Is it just me or does it sound a bit fishy?

 

Having watched the video, I will note that the guy doing the shooting is using a Hornandy A-Max bullet. This means that the tip is plastic and the round is designed to expand when it hits something. Which, from the other tests, seems to be the perfect thing to shoot at this particular configuration of armour. I'd expect ball and AP cartridges to pass right through.

 

I'm also not sure why you mention water, as the armour has none. Rather, UHMWPE is a little bit less dense than water, so this thing would float.

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14 hours ago, Toxn said:

 

Having watched the video, I will note that the guy doing the shooting is using a Hornandy A-Max bullet. This means that the tip is plastic and the round is designed to expand when it hits something. Which, from the other tests, seems to be the perfect thing to shoot at this particular configuration of armour. I'd expect ball and AP cartridges to pass right through.

 

I'm also not sure why you mention water, as the armour has none. Rather, UHMWPE is a little bit less dense than water, so this thing would float.

 Fitty cal AMAXes have aluminum tips.

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1 hour ago, Ramlaen said:

that's a big nope

 

hPMil9o.jpg

Better than the alternative, I guess.

 

I agree that I'd want something more rigid though. Having your liver explode could seriously ruin your day.

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      Because the slide is stamped, and stampings (especially of that thickness) are somewhat limited in how many fine details and contours they can have, the interaction between the slide and the frame works differently in the GSh-18.
       
      Like other short-recoil automatic pistols, the barrel and slide of the GSh-18 are locked together at the moment of firing.  Recoil flings the barrel and slide rearward, which causes the lug on the bottom of the barrel to ride over a helical cam cut into a machined piece of steel located in the frame (this piece also acts as a locator for the return spring, and a mount for a spring-loaded claw whose purpose will be discussed shortly):
       

       
      The barrel then stops against this piece while the slide continues recoiling.  This causes the slide to extract the spent case and eject it.  The slide runs out of velocity as it compresses the recoil spring.  Once it has completely compressed the spring, the slide begins moving forward, which causes it to pick up a new round from the magazine.  Up to this point, the operation of the GSh-18 is like any other recoil-operated pistol.
       
      The difference is with the feeding of the new round into the firing chamber of the barrel.  In most other designs there is some interference geometry between the slide and barrel that prevents the barrel from creeping forward from the force of the round being fed into it.  If the barrel were allowed to creep forward, it would slide back over the helical cam cut and move into the locked position.  This would cause the locking ring splines to bounce off of the locking lugs when the slide came forward, and the gun would not go into battery.  But the GSh-18 cannot be made with this sort of detailed interference geometry because the slide is stamped, and making this approach impractical.
       
      Instead, there is a large, claw-like lever on the right side of the frame.  When the barrel and slide initially retreat during recoil, this claw snaps over a rim on the right side of the barrel.  This claw forcibly holds the barrel to the rear until the slide levers it open at the right moment for locking to begin.
       
      This locking claw allows the use of a simple stamped slide, but it has some advantages beside that.  In a normal pistol, the interference geometry between the slide and barrel causes some amount of friction.  This means that the area where the slide rubs against the barrel is a critical lubrication point:
       

      Lubrication points for a Glock pistol, from the USA Carry lubrication gude
       
      So the GSh-18's slide loses a little less energy from this rubbing, and is also made a little less sensitive to the condition of the lubrication around the barrel.
       
      This is probably as good a place as any to mention that certain features of the GSh-18 bear more than a passing resemblance to the ill-starred Colt All-American 2000:
       

       
      The multiple, radially symmetrical locking lugs of the barrel (relocated on the GSh-18 to the front, of course), the two-piece construction of the slide and broad similarities make me wonder if the All-American 2000 was a starting point for the design of the GSh-18.  If so, it would make the GSh-18 the second time that this design family with visionary qualities was let down by sub-standard manufacturing.
       
      Perhaps the third time is a charm.
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