Multiple hits on a vest

[1858rem]

That sure is some crazy math. Ever hear about the law of conservation of energy in physics?

nope..... i was just takin a wild a$$ guess as far as how to explain this>>>

Assuming we are talking about Kevlar, the end results would most likely be the same. Not from the blunt force trauma but from the fact that a vest when struck by a bullet responds to the rpms by twisting and becoming smaller. By the second or third hit, it is covering an area about the size of a saucer and it looks like your shirt has been poorly stuffed with straw. Not at all like what is shown on TV or the movies. Basically, if he would have been able to return fire without the vest he would have been able to return fire with it. The rearrangement of the vest just makes it more awkward to do so.

......without really knowing much/anything about it

 

[1858rem]

That pretty well sums it up folks!!

Now excuse me while I go unwind my target backstop.

It keeps getting it's panties all twisted up in a wad by those spinning bullets!

Hahahahaha! lol very funny!

There are sure a lot of folks spouting off stuff they have no knowledge of. The 11,250 rpm statement is a classic. Some people don't know when to stay in their own lane and not embarrass themselves when they spout off such drivel.

did i even do my math right?? i always thought it was a lot higher rotational speed untill i even took a guess at how to do the math and was pretty surprised at the result so i posted the ridicules answer i came up with, lots of good humor though, thanks

 

[isp2605]

did i even do my math right?? i always thought it was a lot higher rotational speed untill i even took a guess at how to do the math and was pretty surprised at the result so i posted the ridicules answer i came up with, lots of good humor though, thanks

Your math had nothing to do with it. Your reasoning and knowledge are what's severely lacking if you think the rotation plays a role.

 

[Sport45]

The bullet rpm's are fairly high, but as others have mentioned it would have little to do with the effect on flesh or kevlar.

A 800fps pistol bullet through a 1-12 rifled barrel is spinning 48,000 rpm.

A 3000fps bullet from my 1-7 twist AR is spinning 308,000 rpm. (But is is still only making one revolution for each 7" traveled.)

Bullet rpm equals fps divided by inches per turn times 720.

 

[Double Naught Spy]

I think that it was one of the problems when they first started making vest, that it was just layers and not bonded / sewn together, also you can see movement on the vest in slowmo, but on modern vest as described above, you can be hit multiple time in the same area (not same spot) with out penetration.

You know, even the polymer vests preceding kevlar had layers sewn together, so I don't see the story holding water that vest makers just had the layers laying unattached in a carrier and hence causing the problems you describe.

The product would not function because all the layers would slump to the bottom. They have to be stitched together (or otherwise attached to one another) in order to not collapse.

And now, even loose layers of kevlar don't spin up around the spinning bullet. Yes, you can see movement of the kevlar in slow motion video. It is the pulling of the strands within the weave at the kevlar is 'catching' the incoming round.

 

[Gunfighter123]

A long ansewer short ---YES, he would have lived ---- many , many recorded cases of Police being shot multiple time in their vests and living.

 

[chuckusaret]

Is there much of an increase in the survival rate when wearing a vest against the new ammo. The vest we wore in Nam were POS and IMO was nothing more than added weight to carry when in the bush. When flying door gunner I sat on a breast plate and a flack jacket in an attempt to slow the incoming rounds down. I doubt that it would have had any stopping effect on a .51 cal. I was lucky never experienced a round thru the seat.

 

[isp2605]

There's been major advancements in vests since VN. What LEOs wear won't stop a .51 but then that's not the usual threat. What LEOs wear are usually Level IIIA which will stop up to a .44 Mag. The IIIA will stop the most commonly encountered handgun rds which are the usual threats. When getting into the vests that would stop rifle rds the vests become too heavy, too stiff which restricts movement, and cumbersome for normal duties and most likely would not be worn by the typical LEO. Level IIIA vests aren't too uncomfortable in hot weather and remain flexible so they don't restrict movement.

 

[Steve C]

Mathmatically the rpms the bullet turns is related to its velocity, disance traveled in a minute and the twist of the barrel. Regardless of rpms the bullet will rotate at the same rate as the barrel twist IE. a 1:18 twist will only turn the bullet one rotation for every 18" of travel. If the bullet pushes into the vest say 2" it will only rotate 2/18 or 1/9 of a rotation or about 6 minutes of rotation of a clock, however as the rotations is stopped by the vest you can reduce that b 1/2 so the rotation would only be 3 minutes. I don't think the deformation into the vest would be as much as 2 inches for a relatively low poered round, probably less than 1". As you can see there isn't any twisting of the vest or fibers to any extent.

The same calculations can debunk the nonsense about the buzz sawing of black talons or any other expanded bullet.

 

[iiranger]

Probably maybe...

O.K. "bullet proof" goes back to the days of armor which wasn't very and that got it unpopular much... Why spend a couple years income on tin suits for man and horse when they can be penetrated??? Brits did that nicely at Crecy and Portiers with the "cloth yard" (32 inch) arrows with steel tips that are lubricated with wax (probably bees wax)... and the long bow... and fired in flights of hundreds... 6 per minute was a leisurely pace...

Until recently the body armor was plates, mainly metal, very heavy and while "o.k." not likely to be worn except in the most obvious of situations. Knew a soldier from Korea told me about bakelite/plastic plates but they did not overlap. Bullet hit the plate, great. Went between plates... -0- help. And you were all sweaty from the canvas jacket with the plates...

In US the kevlar has been around since Viet Nam. High friction fibers.

It works like a "pitching cage." The projectile is "caught" in the super strong fibers by the friction of the fibers on themselves... #1). You get a whopping bruise under the armor. If gun is bigger than .38 Special, you spend the night in the hospital for observation against clots, etc. Bruise problems. Impact trauma. #2). If it is wet, forget it. It is about worthless. The friction is lost. Thus the plastic bag container and dislike by officers in hot climes. #3). If hit, the maker usually gives the wearer a new one cause each "hole" is good for about one hit and then, strength lost, worth about as much as a bulky sweat shirt if hit a 2nd time in the same spot. (Most crooks are not that good a shots, but bad luck is back luck.)

In the scene you present, well... if the bad guys were so stupid that they did not notice the officer being much less harmed by the shots to the body and shift aim to the head... bad guys now know to shoot for the head/neck in USA thanks to news coverage of cops "saved" by a vest... then the officer might well have gotten his gun into action and survived or taken a few with him.. MIGHT! But 3 against one is bad odds anytime. And usually, however messed up the killers are on "courage," one will be behind... I would guess his chances at 40%/60% but unless he knew the killers and was on guard... He's toast. Goes with the territory. As was, chances 20%/80% against living. Enjoy.

 

[John Parker]

Bullets don't wind Kevlar up. That's a bunch of BS.

 

[sidheshooter]

Slightly OT, but can anyone tell me if there is a standard time frame for replacement "just because", even if the vest hasn't been shot? Sort of like replacing motorcycle helmets every few years just due to useage wear...

Just curious.

 

[Double Naught Spy]

Unless dates have changed with new materials, general the time frame is 5 years.

With that said, I have tested some old officer IIIa vests (Kevlar) from the late 80s that performed to better than a Level II vest. I didn't have the right calibers to see if it was still fully Level IIIa compliant or not. These weren't closeted vests, but apparently well used and full of body salts, complete with nasty sweat stains.

 

[armoredman]

5 year warrantee - DuPont won't warranttee the fabric after that time period, but usually the material is still good. Have an old vest i have been meaning to try...