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By Chris Taylor

There is a surprising amount that people don’t know about body armor. Of course, what one person doesn’t know could fill a warehouse. There’s always more to be understood, particularly when it comes to body armor. Nevertheless, many do not understand the protection available in a bullet resistant (or bullet proof, as they’re frequently known)  vest, and see it as either complete protection against any weapon or an archaic throwback that today’s modern weapons simply decimate. So which one is correct? . . .

To put it simply, both are correct. Or neither, depending on your viewpoint. Bullet proof vests are available at a variety of levels according to the protection they offer. And while most vests are incredibly strong, they will only protect you against certain kinds of ammunition. The highest levels of bullet proof vests are capable of protecting against some incredibly powerful rounds, but won’t stand up to everything. Conversely, lower levels cannot guarantee protection against the more powerful weapons, but will still provide you with a great deal of protection.

The levels available in a bullet resistant vest are governed by the US National Institute of Justice, which is widely recognized as being the world leader in ballistics testing. The testing standards outlined by the NIJ allows for these levels- NIJ Levels– to be assigned to bullet proof vests according to the size, strength, and speed of the ammunition it can protect you against. Below are some of the most common rounds, the most popular rounds, and the most famous rounds available, and what level of body armor you will need to protect against each.

9mm Parabellum

The 9×19 mm Parabellum, commonly known as simply the ‘9mm’, was developed at the beginning of the 20th century for German manufacturer DWM. The 9mm is credited as being the most widely used handgun ammunition in the world, and is commonly used by Police Officers across the globe. The 9mm is often cited as the reason semiautomatic pistols became more popular than revolvers. At higher velocities a Level II vest is needed, but at lower velocities a 9mm will be stopped by a Level IIa vest.

.45 ACP

The .45 ACP, or .45 Auto, was created for the prototype Colt semi-automatic .45 pistol developed by John Browning. It was first released in 1904, but only gained popularity in 1911 when it was adopted by the US Army for use in its M1911 pistol. Following this it became far more popular, thanks in part to its moderate recoil and high velocity. The .45 ACP also benefits from a low muzzle flash, but is heavy and costly to produce. Protecting against this round requires a vest at Level IIa.

10mm Auto

The 10mm Auto, usually shortened to simply ‘10mm’, was a joint design between the United States and Sweden and first introduced in 1983. Despite boasting superior stopping power, the 10mm never gained the popularity of its shorter counterpart (the .40 S&W). It did, however, gain popularity among certain branches of Law Enforcement, most notably the rescue and SWAT teams of the FBI. The 10mm was designed to be used in semi-automatic pistols, but suffers from high recoil. To stop the 10mm Auto you will need a Level IIa vest.

.40 S&W

The .40 S&W is named for its manufacturer, Smith & Wesson, and was originally deisgned to be used by Law Enforcement Agencies. This rimless cartridge did gain popularity among Officers after its introduction in 1990, partly due to its performance against similar rounds, offering both superior power and improved recoil. The .40 S&W was created as a shorter alternative to the 10mm Auto. Protecting against the .40 S&W will require a Level IIa bullet resistant vest.

.357 SIG

Introduced in 1994, the .357 SIG was designed by its namesake, Swiss manufacturer Sig Sauer. Apart from its reduced recoil, the .357 SIG is practically identical to the .357 Magnum in terms of performance, yet is known for being more reliable. For example, one of the benefits of the .357 SIG is its compatibility with autoloader platforms. However, the .357 SIG never gained the popularity of other similar rounds, perhaps because of its lack of adoption by Law Enforcement organisations. A Level IIa bullet resistant vest is needed against this calibre of ammunition.

.357 Magnum

The .357 Magnum, or simply .357, is credited with beginning the ‘Magnum era’ of handgun ammunition after its introduction in 1934, and has found popularity worldwide. This round was developed in the 1930s by Smith & Wesson in an effort to re-establish themselves as the leading law-enforcement armament provider. The .357 is well-known for its stopping power, and is largely fired from revolvers, although it can be fired from certain semi-automatics, notably the Desert Eagle. A vest at Level II will protect against this ammunition.

.44 Magnum

The .44 Magnum is one of the most famous rounds in the world, featured most famously in the film Dirty Harry. The film is often attributed with the rise in popularity of the bullet, as it had remained relatively unknown for the 16 years previous. The .44 Magnum is famous for its stopping power, which naturally causes muzzle flash and high recoil. The .44 Magnum will need a Level IIIa bullet proof vest.

Chris Taylor is Communications Director for Safeguard Armor.

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  1. good luck getting up after being hit with a 44 mag or 45 acp. you’ll probably have some bruised, cracked, and maybe even broken ribs

    • How can you even put 45 Acp in the same sentience as 44 Mag? The 44 mag has twice the energy and is coming out around 1300 FPS. However the “basic” 44 mag is not going to have the velocity needed to get threw the vest. 45 ACP is typically subsonic at around 840 FPS

    • They not only get up they are still lethal. Getting hit, cracked ribs heck even lethal stuff doesn’t put people or animals down to stay. Don’t buy into the hype. Get out and learn by doing jobs in the business and hunting etc.

      • From my experience .45 ACP is not the gorilla it’s made out to be. Maybe it was the 3.8″ barrel, but the results were less than impressive.

        • Sammy,

          .45 ACP produces really slow moving bullets out of 5 inch barrels: muzzle velocities are around 840 fps. When you shorten the barrel to 3.8 inches, I imagine the muzzle velocity is somewhere around 800 fps. At those speeds, you are relying on the relatively large frontal surface area (.45 inches) and mass (230 grains) of the bullets to incapacitate an attacker. While those characteristics are enough to incapacitate most human attackers, they can be inadequate … and are definitely inadequate for large feral hogs, black bears, brown bears, moose, elk, horses, etc. Have people killed large animals with .45 ACP? Of course. Do they routinely achieve “one shot stops” on large animals with .45 ACP? Definitely not.

          If you want terminal ballistics that have a much higher probability of promptly stopping drug addled humans and large animals with one shot, you need to move up to .41 Magnum, .44 Magnum, .454 Casull, .460 S&W Magnum, or .500 S&W Magnum.

          Note to 10 mm fanboys:
          A 10 mm semi-auto handgun could be a viable choice for stopping large animals due to the fact that the semi-auto pistol platform allegedly enables you to put multiple rounds on target in a short period of time. (Slide-action recoil reduction and single-action triggers enable faster and/or more accurate shots than double-action revolvers.) Even then, you would need a 5+ inch barrel and cartridges loaded to SAAMI maximum pressure with 200+ grain hardcast lead bullets.

    • There is a backface deformation maximum. You shouldn’t be critically injured by a bullet the armor is rated to stop.

    • I can’t speak to bruising, but I’m not sure a 44 mag would actually knock someone down. Most people that fall after being shot do so because it scares the @%$& out of them. Stopping power is still a myth isn’t it?

      • In the movies they get blown off their feet all the time. But we know from old Issac that every force has an equal and opposite force, so how could one handle and fire a weapon with recoil equated to that kind of force?

        • With recoil reducing technology such as compensators, recoil springs and the like. Barrett claims the design of the m82 .50 bmg rifle absorbs more than half of the recoil of the round.

          Another great example is the Kriss vector smg. It redirects the recoil force downward by having the bolt swing down at an angle instead of traveling straight back and forth. They claim something along the lines of 90% reduction in muzzle rise.

          Either way, it’s unlikely that any modern weapon that can be fired from the shoulder actually delivers enough energy to physically knock a person of their feet.

          • As others have pointed out, it’s basic physics – conservation of momentum, to be exact.

            Assume the initial state of the system (target + shooter/gun + bullet) is that nothing is moving – so the total momentum of that system is zero. Conservation of momentum dictates that at any given point before, during and after firing, total momentum has to remain zero.

            Once you have fired and the bullet has exited the barrel, total momentum is conserved, because the momentum of the bullet is cancelled out by the momentum of the shooter/gun (imparted onto them by recoil), which is equal in absolute value, but opposite in direction.

            When bullet hits the target and stops inside, transferring all the energy, the same thing has to happen to conserve total momentum – i.e. the momentum of the bullet has to be transferred entirely to the target. Ignoring losses due to air friction, the momentum of the bullet at the point is still equal (in absolute value) to recoil momentum imparted onto the shooter. Thus, the same exact recoil momentum (but, again, with opposite direction) will be imparted to the target, maintaining zero total momentum.

            Now, if both target and shooter/gun have the same mass, having the same momentum means that they will also have the same velocity. So if both have equal support (e.g. none, if both are standing), you can’t make your target fly without doing the same to yourself.

            Note, however, that this only pertains to weapons that have recoil. The physics of recoilless rifles (which can be shoulder-fired) is very different.

      • Still not true on falling down. Your hoping and wishing for it but that doesn’t make it so.
        Even if they fall it doesn’t mean anything they are still lethal. You can shoot a deer with a rifle much more powerful than a 44 and it runs 100yds before collapsing. You can make a solid hit on a hog with a 44 and watch it spin for 30 seconds before it collapses. Ask anyone who ever shot anyone and you will find that often they don’t fall they keep going even for just a bit. Look at the onionfield incident where 30 seconds changed several lives.
        Its not a zorchiton death ray its a bullet. Seriously guys get out and use them for other than steel or paper.

        • Or ask anyone who’s been shot. For me it felt like getting hit with something ball peen hammer shaped when it hit something bony and a searing 3lbs sledge hammer punch when it hit something soft. The bigger one felt like it was a bigger hammer. Not nearly the kind of pain you’d think. No sensation of the wound being as major as it was (they were still mostly flesh wounds so no surprise there). Still totally unpleasant but the recovery was vastly worse than the perforation. That’s all with low powered pistol hits. I wouldn’t want to experience anything actually powerful. It does not knock you down and I didn’t notice right away that I’d been hit after the first one hit my shin (the one in the side I noticed). I sat down after having done a lot of other things including walking home. I assure you I was fully capable of being lethal afterwards.

      • Yes you are right about the “knock down power baloney”. Even Physics 101 would tell people that is impossible. People today still believe the 1911 myth that it will knock a person down, spin him around like a top or make him disappear in a red puff of mist. There have been documented police shooting where men have taken multiple hits form .12 ga. slugs which measure roughly .70 caliber and that did not knock them down and in one case the fellow did not even know he was hit and kept on shooting back. And by the way the fellow did not die either , he survived. When people fall down suddenly its usually when the spine is shattered or the brain is hit. Other body its even like shattering the heart enables animals such as deer to often run 25 yards and even farther before they finally collapse and in the case of a man he can keep on shooting back at you before he dies.

  2. “357 sig is practically identical to 357 magnum in terms of performance” I was under the impression the magnum rounds had some more powder behind them.

  3. Velocity kills a vest. I don’t think a IIa vest stands a chance against 135 grain full power 10mm. Hell I don’t think a IIIa would stop it. And that’s what I really hate about those armor listings. The list just “caliber” not mass and velocity.

    • No they list type of bullet, mass, and velocity of the bullets that it is rated to stop.

  4. I have always been interested in the fact that you seldom, if ever, see articles about what happens behind the vest once it is struck. I know that the impact of the bullet can cause some severe physical damage even if it doesn’t penetrate the vest, but how much, and how severe? Inquiring minds want to know.

    I’m also curious as to what happens if the round does penetrate the vest. How much does the energy lost in penetration of the vest mitigate the ability of the projectile to cause debilitating injury or death?

    These questions obviously relate to pistol calibers since the average bullet resistant vest stands no chance against most rifles. I have even read somewhere that .22LR fired from a rifle is able to penetrate Level II vests due to its high velocity and minimal cross-section.

    • I’ve been struck in my hard plate from a 5.45 round. It definately gets your attention, but nothing broken and nothing horribly bruised.

      • This. There is a world of difference between soft armor and hard plates. Soft armor will stop most handguns but it’s like getting hit with a sledge hammer. A poorly trained/low fitness individual probably isn’t getting up from that for a few seconds. Hard plates are the real deal. Either the round penetrates or it doesn’t, and all but the nastiest rounds barely make a dent on the far side. If you’re serious about armor hard plates are the only way to go, unless they are simply too heavy/restrictive for you.

        • The nice thing about soft armor is that you can cover more body area with it. So, hard armor for the vitals, soft armor for everything else (just like SAPI vests do it).

      • I took two hits to my ESAPI plates while downrange; the first plate (front) was hit near the bottom edge by a 7.62×39, my second plate (rear) was tagged dead center by a 7.62x54R. Both times it was kinda like getting hit by a fastball and knocked the wind out of me. The 7.62×54 must’ve come from a long way out, if it’d been let loose much closer I would’ve definitely been hurting.

        Those Interceptor vests were uncomfortable and bulky, but they definitely did the job well…. except on the sides. In any case, if I ever get another vest, I’m definitely going for hard plates. There’s a lot of 7.62 and .30 caliber out there, and soft armor just won’t cut it.

        • You’re a damn lucky individual. Thanks for going out there and putting your life on the line.

  5. Frontal area of the round does act vest performance.

    If you had the same weight bullet in 10mm and 45, it would take more velocity to punch through with the 45 vs the 10.

    If you look at armor piercing handgun round, the are almost always “pointy”. Most military and police rifle rounds are already pointy.

    If I recall, there was a lot of hoopla about the 5.7 rounds being AP. Fast and pointy may not make big holes, but they are holes……..

    • 7.62x25mm (7.62 Tokarev) also makes nice holes through a vest. 85gr handgun round @ 1400-1900 fps will punch through most soft body armor available…

      • I’d lay odd that .22TCM could probably defeat soft body armor too, especially if you load your own with FMJ vs. the 40 grain JHP that’s the most commonly available round. That 40 grain JHP load from Armscor is rated at 2000FPS from their 5″ 1911s.

      • I’d lay odds that .22TCM could probably defeat soft body armor too, especially if you load your own with FMJ vs. the 40 grain JHP that’s the most commonly available round. That 40 grain JHP load from Armscor is rated at 2000FPS from their 5″ 1911s.

  6. 168grain steel core .308 sails through both sides. Myth busters demonstrated that on tv.

    • 55gr lead core .2235/5.56 sails straight through AR500 steel within 20 yards.


      • This has not been my experience. It certainly leaves an impression in the steel, but I have yet to have it pass through any of my steel targets.

        • You need a 20″ barrel to get enough velocity for it to work at 20 yards. And it must be 55gr or lighter, 62gr is not fast enough.

      • There are plenty of YouTube videos showing 55gr 5.56 “sailing” through level III plates; however AR500 (the brand name, not the type of steel) pretty much only sells level III+ (their marketing term) plates now, and there are youtube videos of the same 55 gr 5.56 not penetrating that (often done by the same person who did a “sails” through video); apparently not all marketing is vapor-ware.

  7. I purchased a Point Blank Alpha Elite IIA concealable vest a couple months back for my volunteer work with our local Sheriff’s Department. This was after a lot of research trying to determine what was the most reasonable compromise in terms of protection, weight, comfort, and price. I spoke to several friends who are in law enforcement. Body armor is really a complicated subject and it was difficult to find information to compare apples to apples.

    We do motorist assists along I15 which is a major drug corridor. Every time I do that, my butt clenches. I just hope that I never have to find out how well the vest works.

  8. Kevlar has the nice benefit of being heat resistant, although the operator may suffer heat stroke.

    • Gardez, 7 degrees. Six day patrol. So so so in love with the R value of hard plates.
      Shajoy, July, 120 degrees, not so much.

  9. These vests are essentially useless to the common people, unless they happen to be a cop, a security guard, or someone with a hit out on them. I doubt that I know anyone who owns one.

    • Well I guess I’m the weird one. Hard plates in an H harness in the truck. Hard plates in an IOTV at home.

      • Seconded. 2 sets of 3+ plates sitting in my closet with carriers. Not a daily thing, more like a Katrina/Ferguson thing.

        • Soon to be thirded!

          I saw the Star Wars armor that AR 500 helped make for SHOT show and went to their site to look for more info on it. Didn’t find much on the Star Wars stuff, but I was absolutely shocked that I could get a set of their Level III plates and a carrier for $200.

          Haven’t bought it yet. Just finished upgrading my Scorpion and my XD .45. Now that both of those are out of the way though, a set of armor is my next purchase. I mean, why not? It’s only a couple hundred bucks!

        • Clint, careful with AR500 plates. They either need to have a thick coating or you need a good anti-spall carrier. The bullet fragments off of some of those plates will absolutely shred your arms, and chin, and depending on your angle, your throat as well.

    • A gun is useless (self defense wise) to most of us 99.9+% of the time too. Soft armor conceals pretty easily in cool-cold weather. I wear it often when I deliver narcotics and don’t think anyone has ever noticed. In the summer, outside, it is tortuous though.

    • I guess no on has ever been shot during a home break in either. That would just be stupid to be prepared for that.

  10. Aside: “Decimate” means reduce in size or quantity by ten percent. No round does this to a ballistic vest.

  11. Originally posted on a separate comments thread a few months back, but relevant here:

    Bear in mind that the “valid until” date on body armour is there for a reason.
    About two weeks ago we tested this exact point to demonstrate to a client in Afghanistan why they should be buying new PPE when their old stuff “was in great condition”…
    All equipment tested was end of service life, plus one year, but otherwise had not been abused. All equipment was fired upon from a range of 30ft.
    NIJ L-3A PASGT helmet9x19mm ball – clean penetration through one side
12ga. slug – clean penetration through both sides
5.56x45mm – clean penetration through both sides
7.62x39mm – clean penetration through both sides
    NIJ L-4 ceramic chest plate / L-3A soft armour9x19mm ball – no penetration
12ga. slug – partial penetration, plate delaminated, slug stopped in soft armour behind the plate
5.56x45mm – partial penetration, round fragmented but several sections penetrated soft armour behind the plate
7.62x39mm – partial penetration, round fragmented but several sections penetrated soft armour behind the plate
7.62x39mm AP – full clean penetration through hard and soft armour
    The issue is that the common manufacturing process for a lot of ballistic armour is basically a layering one. And over time the bonds between layers break down due to environmental factors (heat, humidity, general movement, etc.), even if there’s no visible damage, which severely degrades the armour’s effectiveness against ballistic impact.
    Clearly YMMV, but we tested a whole lot of armour and found that more or less anything over 3yrs old failed to meet its standard. This across a whole bunch of manufacturers, including reputable US, British and South African brands.

    The real surprise for me was the 12ga. on the NIJ Level 4 plate. I expected it to dump a whole heap of energy and make a real mess of the plate face, but to see it consistently penetrating or partial penetrating was remarkable. Most times the wadding would be caught up in the middle of the plate, but the actual slug would have penetrated right through and stopped in the soft L-3A armour behind, or hung up just as it exited the rear of the plate.
    In any case, it makes the point that plate-carrier PPE absolutely cannot be relied upon for anything higher rated than pistol calibres unless you know it’s new and has been kept in good environmental conditions – and that’s still a lot of trust to place in your kit.

    • Good information! I am hoping my concealable vest makes the full five years since I only patrol once or twice a week for four hour shifts and the bulk of the time I am in an air conditioned vehicle. Since I am a volunteer, our department will not pay for body armor.

    • I think he meant what he typed, Level II. I suspect you would need to step up to Level IIIa with .44 Magnum simply because of the mass involved.

      For example, hot .357 Magnum cartridges launch a 125 grain bullet at 1600 fps versus hot .44 Magnum cartridges that launch a 180 grain bullet at 1600 fps. Granted, the .44 Magnum has more frontal area than .357 Magnum. It just plain has more mass that is harder to stop.

      Now, if you want to get into really scary territory, a .44 Magnum cartridge loaded with a light bullet (something like 135 grain if anybody even makes something like that) would probably have a muzzle velocity north of 1800 fps. That would definitely punch through Level II vests … and would give Level IIIa vests a run for their money at point-blank range.

        • Energy doesn’t matter as much as velocity.

          Consequently, .357 out of a carbine is a very different proposition.

  12. I was rather surprised to find out that human sweat will deteriorate any bullet proof vest and that is sad because they are not cheap either.

    It is interesting to note that in 1945 the U.S. Military tested the 1911 .45 ACP against a Canadian 9mm High Power and they were shocked when they found out the .45 acp with fmj bullets (military loadings) bounced off a WWII helmet at a scant 35 yards while the 9mm penetrated the same helmet at an astonishing 125 yards and might have done so even further but no one that day could hit the helmet beyond 125 yards. I wonder what would have happened if they had tried a bit longer and succeeded in hitting the helmet at a further distance. So much for the myth that the .45acp is such a superior round. Reality proved gun writers once again did not know then and do not now know much about handgun lethality. I think too the 1980’s tests on pigs in Mexico by Pistolero Magazine proved much the same thing and that was the .45 acp lethality was and is a myth as their own testing showed that on pigs it killed no better than the 9 mm or .38 special. The “Moro Myth” about dope crazed Zombie warriors impervious to pain was also another dreamed up Gun Writer Myth designed to sell pistols for Colt both to the Military and to Civilians both of which never bothered to shoot animals with the caliber to find out the real truth.

    • Penetrating a helmet (or any type of armor) at a greater distance indicates only that the round has a higher velocity; it says nothing about its effect on the flesh. M855 also penetrates helmets better than M193 – it was one of the criteria that led to its adoption – but its terminal ballistics in the human body make it a worse round.

  13. I have a one by my bedside for things that go bump in the night….old habits for hard. …May rethink that now I am out of California. ..

  14. Author please check this data in para 2. Levels reversed?

    “At higher velocities a Level II vest is needed, but at lower velocities a 9mm will be stopped by a Level IIa vest.”

    • No, it’s accurate. In order of increasing resistance, the levels go: IIa, II, IIIa, III.

  15. I quit reading when 9mm required a II, but .357 Sig could be stopped by Level IIa.

    One of those is incorrect.

    • If I remember correctly, “high-velocity 9mm” means +P fired out of a submachine gun with at least 10″ of barrel.

  16. The answer for most people like me who want something functional and long lasting in case of shtf is steel plates in a fitted carrier. I am not going on 72-hour combat deployments. I am not going to be wearing armor around the muggles. I would only be wearing it in a really screwed up situation in defense of my residence. Steel plates have longer operational lifetimes than laminate plates and vests. So for someone like me a decent set of plates and a carrier is a cheaper more effective solution.

  17. Ok, I really wish I’d gotten in on this earlier but here goes…

    What about the dreaded .9mm?

  18. This is a great article. I never figured out why people are so gun-ho about carrying a firearm and being prepared for a gunfight…but then they ignore body armor. Why? Especially since the bad guy usually has the first strike advantage. And then there’s the preppers. And then there’s the people who desire protection, but don’t like guns… So something like this should be a total sell out to almost everyone.

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