GunXpatriot
New member
So I seen a video on making homemade "bulletproof" glass. It was a video by MindToMachine. Here is the link. http://www.youtube.com/watch?v=W0I21Hjjwcg
So I think I'm starting to understand the science behind it, so if someone understands this better than I do, or if I'm wrong, definitely let me know.
So this is my understanding, and I could be wrong, but MindToMachine's setup was actually lacking in efficiency with 2 layers of acrylic. So here goes...
You layer a material with some amount of flex, and behind it, a brittle, more "breakable" material. When the bullet hits the material that can flex slightly, the flexible material takes some of that shock, and then transfers it to the more brittle material. So before the bullet has even penetrated, energy has been reduced. This done multiple times, has a cumulative effect, and with enough layers to deposit energy, can even stop full-power rifle rounds.
Did that sound right? I guess that would make sense, because that was the conclusion I had reached before really looking, just by observing what the glass looked like, and how the last layer of glass would often be unscathed. I guess it just comes down to making a projectile hit a larger area than it actually is, and I think that would kind of sum up what's happening. In MindToMachine's video, he used a soft(er) material (acrylic) and backed it up with a harder, but still soft material (polycarbonate).
I feel like some of that was wasted effort, because (from research) it seems that in actual ballistic glass, the two acting materials are Polycarbonate and Glass, polycarbonate being the more flexible material to transfer the energy/check into the glass, which shatters in-between the layers of polycarbonate.
It's just a guess, but I feel like in comparison, if there had been another layer of Poly in-between the two layers of acrylic, the test would have been even more favorable, but that's just assumption. After all, that would give it an extra layer of energy absorbtion vs the two layers of acrylic.
So in that sense, I wonder how layered Acrylic to Polycarbonate compares to layering polycarbonate to glass. I would think that the glass would be able to absorb more energy, judging by the way it shatters, but I'm also pretty sure it's more brittle as well...
I guess the only way to figure it out, would be to try both myself, or maybe even other materials, and just see how many layers/sheets each caliber will make it through.
I'd like to be testing with .22lr (probably High Velocity HP's, as well as round nose, to see if they differ). I'd probably like to work up A/P's (not armor-piercing, I'm talking a layer of acrylic/polycarbonate). So see what happens with one layer A/P, then double to A/P/A/P, rather than doubling up layers of acrylic or Polycarbonate. I'll probably then move up to whatever it takes to stop .22WMR, because 40gr bullets traveling over 2000fps should penetrate pretty deep, and considering small diameter of the bullet, the effects may be surprising. Would try soft point and round nose, both 40gr I believe.
I'd then like to test out, maybe, 00 buck, #3 buck, maybe a slug or two, one 20 gauge, one 12, and MAYBE even work up to 7.62x39. I don't think I'll be able to layer it enough for it to work, but it's be pretty damn cool for a youtube vid, I bet. Homemade glass stopping an intermediate rifle round. I'd probably try it first with the TulAmmo Hollow Points, because I feel like it may deposit energy better than a "sharper" fmj. Then, see how the fmj compares, if I were to ever get that far.
Anyway... Enough with my nerd rant. Anyone ever mess with this stuff at home? What materials did you use? What thickness were the sheets? Seems like MTM was using the thinner sheets of Poly, which I think were like, .09" thick. I believe the acrylic sheets were just a little bit thicker.
But yeah, for anyone who's messed with this stuff, definitely tell me anything you know or have found out. Thanks a lot!
So I think I'm starting to understand the science behind it, so if someone understands this better than I do, or if I'm wrong, definitely let me know.
So this is my understanding, and I could be wrong, but MindToMachine's setup was actually lacking in efficiency with 2 layers of acrylic. So here goes...
You layer a material with some amount of flex, and behind it, a brittle, more "breakable" material. When the bullet hits the material that can flex slightly, the flexible material takes some of that shock, and then transfers it to the more brittle material. So before the bullet has even penetrated, energy has been reduced. This done multiple times, has a cumulative effect, and with enough layers to deposit energy, can even stop full-power rifle rounds.
Did that sound right? I guess that would make sense, because that was the conclusion I had reached before really looking, just by observing what the glass looked like, and how the last layer of glass would often be unscathed. I guess it just comes down to making a projectile hit a larger area than it actually is, and I think that would kind of sum up what's happening. In MindToMachine's video, he used a soft(er) material (acrylic) and backed it up with a harder, but still soft material (polycarbonate).
I feel like some of that was wasted effort, because (from research) it seems that in actual ballistic glass, the two acting materials are Polycarbonate and Glass, polycarbonate being the more flexible material to transfer the energy/check into the glass, which shatters in-between the layers of polycarbonate.
It's just a guess, but I feel like in comparison, if there had been another layer of Poly in-between the two layers of acrylic, the test would have been even more favorable, but that's just assumption. After all, that would give it an extra layer of energy absorbtion vs the two layers of acrylic.
So in that sense, I wonder how layered Acrylic to Polycarbonate compares to layering polycarbonate to glass. I would think that the glass would be able to absorb more energy, judging by the way it shatters, but I'm also pretty sure it's more brittle as well...
I guess the only way to figure it out, would be to try both myself, or maybe even other materials, and just see how many layers/sheets each caliber will make it through.
I'd like to be testing with .22lr (probably High Velocity HP's, as well as round nose, to see if they differ). I'd probably like to work up A/P's (not armor-piercing, I'm talking a layer of acrylic/polycarbonate). So see what happens with one layer A/P, then double to A/P/A/P, rather than doubling up layers of acrylic or Polycarbonate. I'll probably then move up to whatever it takes to stop .22WMR, because 40gr bullets traveling over 2000fps should penetrate pretty deep, and considering small diameter of the bullet, the effects may be surprising. Would try soft point and round nose, both 40gr I believe.
I'd then like to test out, maybe, 00 buck, #3 buck, maybe a slug or two, one 20 gauge, one 12, and MAYBE even work up to 7.62x39. I don't think I'll be able to layer it enough for it to work, but it's be pretty damn cool for a youtube vid, I bet. Homemade glass stopping an intermediate rifle round. I'd probably try it first with the TulAmmo Hollow Points, because I feel like it may deposit energy better than a "sharper" fmj. Then, see how the fmj compares, if I were to ever get that far.
Anyway... Enough with my nerd rant. Anyone ever mess with this stuff at home? What materials did you use? What thickness were the sheets? Seems like MTM was using the thinner sheets of Poly, which I think were like, .09" thick. I believe the acrylic sheets were just a little bit thicker.
But yeah, for anyone who's messed with this stuff, definitely tell me anything you know or have found out. Thanks a lot!
). The Taliban had been transporting mortars in it, and took a lot of fire from a U.S. mounted patrol, when they were captured. There were four .50 BMG bullets lodged in the windshield (4" inches thick), and several .30 caliber bullets in one of the side windows. (Yea, visibility wasn't the greatest...)
