The Bulletproof Glass Rating System Explained

If you’re looking to install bulletproof glass, your first question is going to be, “How do I know this will stop a bullet?”

The Role of Underwriters Laboratories (UL)

Stroll through your house and take a look at any gadget that could conceivably hurt you – the toaster, the TV, even the light sockets – and you’ll likely find a UL certification sticker. This sticker indicates that the manufacturer submitted samples to Underwriters Laboratories, the nation’s leading third-party product safety certification agency. UL tests products to confirm that they fit within established safety specifications. In the case of bullet-resistant barriers, that standard is UL 752, “The Standard of Safety for Bullet-Resisting Equipment.”

Bulletproof Glass Ratings

The eight ballistics grades are self-explanatory – provided that you know details like 7.62mm ammunition is used in an AK-47, 5.56mm ammo in an M16, and that “.30 caliber rifle lead core soft point” basically means a hunting rifle. Let’s simplify things: 

  • Level 1 barriers will stop three shots from a 9mm (arguably the world’s most common sidearm). They are used most by small businesses looking to deter crime.
  • Level 2 barriers will stop three shots from a .357 Magnum (heavier ammunition moving at higher velocity). Frequently present in businesses with more increased security threats, such as financial institutions. 
  • Level 3 barriers will stop three .44 Magnum bullets (each of which is twice as heavy as a 9mm and moves significantly faster). Police stations and government buildings with severe safety threats often choose these barriers.

Eight Levels bullet resistance

The Level 4 Challenge

In order to pass the Level 4 ballistics test, bulletproof glass must stop one shot from a .30-06 hunting rifle. This might seem easier than the Level 3 test since it’s just a single, lighter bullet. But that bullet is designed for penetration, and it travels 1200 feet per second faster than the .44 Magnum. What’s even crazier: the Level 4 test is actually harder to pass than Levels 5, 6, or 7. 

As Total Security Solutions vice president Jim Richards explains, the .30-06 bullet “is 180 grains of lead moving at 2540 feet per second. You have a tremendous amount of velocity there with a big old piece of lead. Level 5 can be difficult, but still, it’s one shot of a 7.62 [just a touch heavier than a 9mm]; so it’s moving faster, but it’s a lot lighter.”  A good Level 4 system can often pass the tests for Levels 5, 6, and 7 with little or no modification and might even pass the Level 8 test (a five-shot burst from an AK-47). “It’s not guaranteed,” Jim is quick to point out, “but it’s pretty well established that if you can stop a .30-06, you’re set.” For this reason, Level 4-8 systems are most commonly installed in buildings where there is a significant threat of assault, such as military and government institutions.

The Curiously Organized Bulletproof Ratings

Like many people in the bulletproof industry, Jim is genially perplexed by UL’s rating system.  Practically speaking, Level 1 bulletproof glass can often provide Level 6 and 7 protection. Here’s how: the Level 6 “Uzi” test is a five-shot burst of the same 9mm ammunition used in the Level 1 test. So if a system can withstand the three bullets in the Level 1 test, it’s likely it will be able to stop at least two more. 

The Level 7 “M16” test uses ammunition traveling more than twice as fast as the Level 1 and 6 tests, but those bullets are less than half the weight (M16 bullets are only slightly bigger than the .22s used in a squirrel rifle). It’s the extremely high speed of these 5.56mm bullets that causes damage on the battlefield, mainly through hydrostatic shock, an effect limited to living creatures and not found in bulletproof glass.

The underlying rationale in the seemingly disorganized UL rating system is this: It’s not ordered according to the threat to materials, but rather the threat to the humans standing behind those materials.  

In practice, M16s and Uzis – with their fast, light rounds – aren’t very dangerous to a piece of bulletproof glass. But their fully automatic firing capacity is deadly to humans. Battlefield and emergency room records confirm that their propensity is to empty the clip when people are shooting at other people. This fact implies that, despite the Level 4 deer-hunting rifle’s acrylic-shattering power, it’s an uncommon personal weapon and has a lower rating. Semi-automatic .30-.06 rifles are rare, and the long-barreled rifle is designed for accuracy over distance, making it difficult to use in the close confines of a gas station or bank. The Uzis, M16s, and AK-47s used for the Level 5 through 8 tests are notorious for their lethal full-auto fire, and therefore pose the highest potential threat to human life.

With this in mind, choosing which level of glass is necessary for your facility can seem daunting. TSS experts are here to help – get in touch today.

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