Archive for the ‘Shoot Tests’ Category

In the previous post, an oft-repeated Internet legend regarding .22LR and light body armor was examined. .22LR has a reputation as a very high penetrating round, more so than .45 ACP. In this post, the results of an objective shoot test to determine the validity of that legend are posted.

The outcome was quite informative

As mentioned earlier, four panels (two 7-layer Level I equivalent, and two 12-layer Level IIA equivalent) were constructed. A block of #1 Roma Plastalina modeling clay was used as the backing, both to provide the requisite yielding surface for proper functioning of the armor, and to act as a witness panel for purposes of backface deformation/penetration evaluation.

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Round used was the Remington Viper Hypervelocity 36gr. copper-washed truncated cone round, with a listed MV of 1410 FPS (out of a 20″ barrel).

Test platforms were a 4″ barrel and a 16″ barrel.

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First up was the 4″ barrel and level I panel. Not surprisingly, the round was stopped by the first layer of material. Backface deformation was 11.65mm (for reference, the NIJ allows soft armor up to 44mm of backface deformation and still pass). Note the unburned powder near the impact.

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Next up was the 4″ barrel and level IIA panel. Even less surprising, the round was stopped in the first layer. Backface deformation was 11.23mm. Note the crater was wider than the level I impact, showing that the force was spread over a larger area due to more fibers being involved in the arrest of the round.

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Next up was the 16″ barrel and level IIA panel. Out of a 16″ barrel, this round is really moving (at least 1300 fps). The round penetrated four layers of material, and was stopped by the fifth. Backface deformation was 12.55mm.

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Finally, the test everyone was waiting for: the level I panel and 16″ barrel. To dispense with the suspense, the round penetrated. It penetrated all 7 layers, with major fragments caught by the 7th. A surprisingly deep cavity was created (most likely due to fragments and expanding muzzle gases) 68mm deep into the clay.

So, thus ends (hopefully) internet rumors surrounding soft armor penetration by .22LR. What can be gleaned from this test: level I armor will stop what it is rated to stop, at least as far as .22LR.

Even though HV rounds were used, out of a 4″ barrel they cannot achieve a full powder burn, and so the velocity does not exceed the 1050 fps limit stipulated by level I. However, level I SHOULD NOT be relied upon to stop .22LR from a barrel longer than approximately 10″ (the point at which the velocity threshold is exceeded). As this test demonstrates, reading the specs for your armor is VERY IMPORTANT.

I do not recommend the use of level I armor, unless there are NO other alternatives. As can be seen, the extra layers of level IIA make a tremendous difference in terms of round-stopping ability. IIA should be considered the absolute MINIMUM for soft armor, and level I be retired as a ballistic rating.

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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.

In several of my posts, I mention that while UHMWPE UD armor is an excellent choice for certain applications, and has material advantages over woven or laminate Aramid ballistic fabrics (higher potential V50, positive buoyancy, UV resistant, waterproof), it suffers from several glaring weaknesses (degrades to complete ineffectiveness above 170F, no breathability, delaminates/curls, and is WEAK AGAINST CONTACT SHOTS).

It is important to reiterate that last weakness: a large number (if not the majority) of self-defense and duty scenarios take place at 0-5 feet, where contact shots are a high likelihood. Woven Kevlar soft armor has shown to provide EXTREMELY good protection against contact shots (defined as the muzzle of the weapon being in physical contact with the vest or armor panel). The point at which Kevlar chars is around 500F, and it will retain its strength below this temperature.

The failure mechanism for UHMWPE in contact shots is the high temperature propellant gases that exit the muzzle microseconds after the bullet. These gases heat the area surrounding the muzzle and bullet path, and cause the laminate to melt/denature. This allows the bullet to penetrate much further than would normally be possible. In the case of large caliber revolvers (with a large muzzle blast footprint), this can allow the round to completely defeat the vest.

Test Round

Test Round

For the sake of the test, the round chosen was the .357 Magnum, rather than a .44 Magnum, as I wanted to see if the (relatively!) more modest caliber would still defeat the level II ballistic panel. The panel consisted of 15 layers of Dyneema SB-38. Round chosen was Hornady Custom 158 gr. XTP @ 1250 fps muzzle velocity, from 6″ barrel. The level II panel is specced to stop an equivalent round.

Test Panel

Test Panel

Backing

Backing

The panel was placed against a backing material consisting of 8 layers of bubble wrap, covered in a dish towel. In retrospect, this was probably a bit too “springy,” giving the panel an advantage by permitting it to move away from the hot muzzle blast faster than if the armor was being worn.

Test Panel Ready To Shoot

Test Panel Ready To Shoot

The test panel and backing were placed upon the ground, and the muzzle pressed firmly (but not forcefully) against the surface. The round was discharged into the center of the panel.

First shot

First shot

First shot, through the backing

First shot, through the backing

First shot, rear of panel...

First shot, rear of panel…

The panel was defeated, showing that the muzzle blast had melted a moderately large area around the point of contact. The round penetrated the backing and buried itself into the dirt (as shown).

To verify, a second round was fired into the lower left area of the panel (away from the heat affected zone of the first round). The second round performed identically, burying itself into the dirt beneath the panel.

Second Contact Shot

Second Contact Shot

Second Round, showing penetration

Second Round, showing penetration

Second shot, layers peeled back

Second shot, layers peeled back

Second shot, showing exit into backing...

Second shot, showing exit into backing…

...And into the dirt

…And into the dirt

Conclusions:

The results of the test shows that UD UHMWPE laminates are at risk vs. contact shots. Heat from the muzzle gases (especially medium to large caliber revolvers) “blazes a trail” so to speak, for the round to penetrate further than it normally would.