At the bank, I see that their bullet-proof glass looks like a really thick layer of plexiglass. I can buy plexiglass at Home Depot or Lowes. How thick of plexiglass is equivalent to what kind of protection?

Thank you for your help.

bullet resistant glass is made of a laminate of hardened glass and polycarbonate. The kind of protection depends on the rating of the bullet resistant glass. Some will only stop small pistol calibers, some are ment to stop larger rifle rounds.

Plexiglass is a totally diffrent material, but if you use enough of it, it will propably stop a bullet. Although i'm not sure that would be practical...

I'm doubtfull that those things at the bank are plexiglass, probably something a lot tougher. But then they may not really be bulletproof, just something to prevent a bg from entering. I haven't asked at a bank, and doubt that they would tell me if I did.

Plexiglass from a home store, in my guesstimation, would not be all that bullet proof. It can get stress cracks pretty easily. Stuff scratches badly too, and will become cloudy unless you clean it with the proper stuff...

The banks are usuallu using a 3 layer system - not 100% sure what the OUTER layers are (which are fairly thin) - they are mostly an "anti scratch" layer - the middle is polycarbonate - aka Lexan. Totally different stuff than plexiglass

http://en.wikipedia.org/wiki/Lexan

http://en.wikipedia.org/wiki/Plexiglas

I worked in a city hospital that installed 2 inch thick bulletproof glass in the window at triage, the first place folks come to on their way to the ER. First issue was that they installed the bulletproof door and window in walls that were otherwise made out of metal studs and sheet rock, neither noted for their missile-proof qualities. There was also a 6 inch hole in the middle of the window, designed to permit conversation between nurse and patient.The hole was protected by a metal grill-which grill pretty well precluded the passage of intelligible speech. So they removed the grill, leaving a hand and handgun sized hole in the middle of bulletproof glass, surrounded by non-bullet-proof wall. Beware the false security conferred by half-measures-

The bank where I work has a "glass" system. It is layered glass and polycarbonate and a couple of inches thick, and super heavy. BUT not "bulletproof." No such thing. It is rated to resist "medium power small arms." No one is sure what that is exactly, but I would not trust it against a .223 or 7.62 round; maybe not even a .357.

I think Mythbusters did a show on this, and it stopped all the hand gun calibers they hit it with. Then they hit it with a 30-06 and it blew through 2 panes of the "glass" they were testing, and kept on going. . .

This is not exactly what you are asking but, if you want something thin that will give you blast and impact protection you might want to look at some of the high tech window films that are available. At best it will only stop small pistol bullets, but it will keep the window intact for wind, impact, and explosions. If you want more information web search safety and security window film. The down side is I have not seen any available as a do it yourself install.

So I guess if you want to blow through this stuff an M-14 would be the way to go?

WW2 and sombody with to much idle time tested a english longbow with a vintage armour piercing point against the bullet proof plating used in RAF gun turrets. The arrow went clean through, the incident was made a state secret and our yoeman archer spent the war in protective custody.

Regardless of what you use. If you hit it hard enough it will be broken. Conversely if you make it thick enough it will stop or absorb most impacts.

I saw on the show, "How Its Made" they made impact resistant windows. Primarily to stop flying debris during storms. It consisted of 2 layers of tempered glass with a thin layer of a plastic film sandwiched between. The film looked about as thick as Saran Wrap. The whole thing was baked to seal the pane. To test it they fired a 2x4 at about 160mph to test it. The window was damaged but the 2x4 bounced.

The film is the secret. It flexes and distributes the force over the entire area rather than just the point of impact.

To use Plexiglas you would need to build up several layer like laminate armor. You would need some type of flexible plastic sheeting between each layer. They you would need to heat the entire thing somehow. Hot enough and long enough to fuse it together but not so long and hot that it is damaged. Very tricky. To stop what you desire you would need to experiment to find out how thick it would need to be.

To stop hunting lever rifle round I would think you would need to be at least an inch thick.