If you are in the domain of guns and ammunition for a while, you must have heard about one of the most frequently asked questions, “Which one is the stronger, a bulletproof vest or a bulletproof glass?”
First of all, be clear of the fact that everything comes with its own set of advantages and disadvantages. While one suits you the best, it might be the option not even considered for others. For example, if you want to stop high speed 9 mm bullets, you will need a best military tactical vest that is around 1 cm thick and weighs 5 kilos per square meter. And if you want to stop a 7.62 NATO rifle round with a lead bullet (M-80) you need a ceramic plate that has a silicon carbide with aramid backing and is 2 cm thick and weighs 28 kilos per square meter.
Now, if you are using a bulletproof glass for the same level of protection against 9 mm, you need a glass that is 22 mm thick and weighs 45 kilos per square meter. And if you are standing against a 7.62 NATO rifle, you would be safer behind a bulletproof glass that is 43 mm thick and weighs 90 kilos per square meter.
As it is quite clear, in general, you can say that for the same thickness the vest will stop a bullet better. However, it depends on their build and quality. The glass made up of plastic polycarbonate is very tough, rigid, and optically pretty clear as compared to the other variants. A vest that is woven from fibers and is tough, flexible, that you can’t see through will be the best when you are facing the barrel.
While the durable vests can take a lot more hits before failing, on the other hand, some glasses also have return fire capability which enables you to shoot from the inside and the bullets will pass the glass. Also, ceramic plates only stop rifle bullets when the tiles are facing out. So, the placing of the glass plays a major role and if you place the ceramic plate backward the 7.62 will pierce it.
On the other hand, the best Body Armour used by operators like from the JSOC like Delta Force and DEVGRU SEALs uses Kevlar or other similar woven fibers like Dyneema and Spectra that gives a whole new level of durability added to it. These types of vests also contain both ceramic and TITANIUM plate inserts that can withstand and stop even the very powerful Dragunov sniper rifle rounds.
However, no Body Armour is available till now that will be able to stop a .50 cal (12.7 x 108mm) round unless you use a glass. If you want to stop a .50 cal round you would need to have a glass plate that is at least 4 inches and is a Bullet Resistant glass. These types of glasses are made up of a composition of glass sheets and plastic films that are bound together in an autoclave and gives it the strength it requires. Also, keep in mind that flexibility is one of the major reasons it can slow down a bullet and is also one of the things to consider.
At last, there is no clear winner of the comparison as each of them has its pros and cons. You need to choose the best which suits you the most depending on the protection you require. In general, if you are not short of cash, try to go for both a vest and a glass if you need security against bullets because you never know what ammo is launched towards you.