Several years I had the opportunity to shoot at bullet proof glass. We had two types of glass. One had 3 layers and was a out 3/4" thick. The other piece had 5 layers and was about 1.25" thick. The thicker glass was higher quality and for use in banks and so on. Both pieces were about 4 foot by 3 foot in size.
The loads I had were a 223 with 55 grain soft point, 308 with Australian FMJ military and 144 grains and 375 loaded with 300 grain Sierra and some older Remington 300 grain steel jacketed FMJs
The 3/4" glass stopped the 223 but I would not like to have been standing behind it, you would have need glasses. The 308 went through and embedded in an 8" tree we had the glass leaning against.
The 5 layer stopped the 223 completely. You have put your face and inch from the glass and without waeing glasses. The 308 militaty 144 grain FMJ was stopped and if you were wearing glasses you would have been OK standing behind it. In fact the 308 on the 5 layer high quality glass was similar to the 223 on the 3 layer lower quality glass.
The 5 layer glass stopped the 300 grain Sierra from the 375 but you would be in trouble if you face was behind the glass and even if you has been wearing glasses. The 300 grain steel jacketed FMJ went through the 5 layer glass and also the 8" tree behind the glass.
