Posts Tagged ‘soft armor’

I am pleased to announce that the highly anticipated D-Rmor Gear Extreme Duty Plate Backers (and Cummerbund Panels) are now available for purchase!

In celebration, during the entire month of July, I will be offering extras for all Plate Backer/Cummerbund orders over $100:

Your choice of one of the following:

Free Shipping
Upgrade to FR 500D Cordura Outer Shell
D-Rmor Gear PVC Touchmark Patch
D-Rmor Gear Armometer
D-Rmor Gear Armor Material Field I.D. Guide

Check out all the options available here:

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For several years it has been debated whether or not .22 LR could or could not penetrate soft armor vests.

Originally, in the 1970’s, Kevlar soft armor was developed to protect Officers against common street threats, which typically were .22 LR LRN, .32 ACP LRN, and .38 SPL LRN. Threat level I vests were certified to stop these ubiquitous, low-velocity threats. As time went on, the threats escalated, and more powerful rounds became common, necessitating thicker vests. But, with the advent of the internet, rumors persisted and spread that called into question whether or not the .22 LR could pose a valid threat to lower level soft armor (I and IIA).

Level I soft armor is seldom seen in this day and age. Typically comprising between 6 and 10 layers of woven aramid, it lacks the thickness to provide sufficient protection against backface deformation. Surprisingly, Level I armor will often stop rounds such as .45 ACP hardball @ 850 FPS, or even .40 S&W. However, these rounds leave a very large backface signature, regardless of whether they are stopped by the armor.

.22 LR has the distinction of being a very good penetrator, primarily due to basic physics- it has a very small frontal area, and can achieve relatively high velocities (1400 FPS from a 16-20″ barrel is not unheard of in certain loadings, I.E. CCI Velocitors). However, it is not a jacketed round, and therefore deforms fairly easily.

The NIJ specifications for Level I call for it to be able to stop .22LR LRN at or below 1050 FPS. Now, it is very important to note the velocity threshold- most longer barrels (above 10″ or so) push .22 LR above this velocity, and therefore can be expected to defeat level I armor. The ongoing debate on the Interwebs rages, but without paying much attention to the distinction between .22 out of a short barrel (handgun) vs. a long barrel (rifle). In order to (hopefully) put this debate to rest, I am posting a test.

This test is aimed at settling the longstanding debate on whether .22 LR is a threat to lower rated soft armor (I and IIA) Furthermore, it seeks to establish whether it is a viable threat only in longer barrels, or both long and short barrels, when faster ammo/more pointed rounds are used.

For this test, the ammo used is Remington Viper 36gr. Hypervelocity round, which features a solid copper washed truncated cone lead bullet and a stated MV of 1410 fps (out of a 20″ barrel). This round was chosen as the shape is more conducive to penetration (smaller frontal cross section). This is fired from a 16″ and a 4″ barrel, from 12 inches.

The panels (two level I and two level IIA) are identical, and will each be shot only once to allow for their full ballistic potential to be evaluated vs. each barrel length. The level I panels comprise 7 layers of Kevlar 29, while the level IIA panels comprise 12 layers of the same material. The backing material is Roma Plastalina #1 modeling clay, to allow backface deformation/penetration to be evaluated and observed.

Stay tuned for the results.

And so it was that a great need was upon the land. With projectiles achieving higher velocities, and greater penetration, Nylon just was not cutting the mustard. Even though it excelled silk for use in soft armor, it still lacked the requisite tensile strength to stop modern copper jacketed handgun rounds in anything approaching wearable ADs.

In 1965, a Dupont chemist named Stephanie Kwolek stumbled upon a new material while searching for alternatives to steel in tire reinforcements. This new material had a tensile strength 5 times that of steel on an equal weight basis. The structure resembled natural silk, but what made Kevlar outstanding was the propensity for the fibers to form cross-linked hydrogen bonds at 90 degrees to the polymer chain. This gave the new fiber exceptional tenacity, making it ideally suited for use in ballistic armor.

This, combined with excellent heat and flame resistance (Aramid fibers do not burn, they char at around 700 F), lead to a resurgence in concealable personal body armor. Richard Davies, founder of Second Chance, immediately saw the potential of this fiber, and the modern “bulletproof vest” was born.

Kevlar is the trade name for aramid fiber developed by Dupont, but there are several different brands of aramid fiber, including Teijin’s Twaron. Though originally discovered by Dupont, Teijin, a Netherlands based company, perfected and patented an aramid fiber processing method that Dupont later licensed to use themselves. Whether we are talking about Kevlar aramid or Twaron aramid, the properties are very similar.

To this day, aramid is widely used in armor applications. During the 70’s and 80’s, the only form used was woven fabric, cut and layered up to 35 plies deep. In the 90’s, new iterations of bullet resistant composites were brought to market, including laminates.

Laminates were introduced in search of the ever moving goal post of thinner and lighter armor. Of course, as has been the case throughout history, heavy and cumbersome armor is not fun to wear. To get folks to wear their armor, thin and light make sense. However, as will be seen, laminates were not necessarily better, and could even be seen as a step backwards (at least the first and second generation iterations).

Laminates such as Goldflex and Gold Shield utilize polypropylene films (chemically similar to food preservative film) to sandwich unidirectional aramid fibers in alternating 0 degree and 90 degree layers. Admittedly, this results in a very good material for stopping bullets, including hits near the edge of a panel, and at acute angles to the panel.

Unfortunately, several drawbacks rear their ugly heads with aramid laminates. First off, they have the breatheability of plastic wrap. Which is zero, since similar materials are used as vapor barriers. Secondly, the plastic film has a nasty tendency to melt when the panel is subjected to the hot muzzle blast of contact shots (an event all-to common in the course of law enforcement). In contrast, woven aramid is extremely effective at resisting contact shots. Finally, armor made with first and second generation laminates experience accelerated wear, since the adhesion of the film is degraded by repeated exposure to flexing, heat, cold and moisture.

While an armor built with woven aramid could reasonably be expected to survive (and remain fully effective!) for over 25 years (and I have personally verified that they HAVE), a laminate constructed armor is usually toast after only two years of normal wear. The edges curl, the layers peel apart, and the ballistic effectiveness drops to unsafe levels. In much the same way that a chain is only as strong as its weakest link, first and second generation laminates are hobbled by their use of, essentially, plastic wrap in their construction.

Next episode, we will look at another laminate, one that has great numbers, but hidden dangers…