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Old February 22, 2009, 08:31 PM   #1
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Bulletproof Cast Aluminum Thickness...

I'm thinking of making a bullet proof shield out of cast aluminum. I have the equipment to cast aluminum and a bunch of old lawnmowers and scrap aluminum I can use, but I can't seem to find any info on how thick the aluminum must be to stop a .223. Anyone know where I can get this data? I know I can cast a bunch of different thicknesses and just take it to the range and test it but I was hoping I could find some specs to make it easier. I did a Google search but didn't come up with anything.

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Old February 22, 2009, 09:54 PM   #2
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Don't really know, but I would question the average man's ability to hold on to the thing when it is hit by a round.
"Suppose you were an idiot, and suppose you were a member of Congress, but I repeat myself." Mark Twain
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Old February 23, 2009, 12:46 AM   #3
Don H
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This thread from the archives shows 5.56 M193 penetrating 1/4" boiler plate at 100 yards.

This site shows .223 going through 5/16" steel plate

I suspect that the aluminum would have to be rather thick to stop a FMJ .223 at fairly close range.
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Old February 23, 2009, 01:17 AM   #4
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I doubt if those shields are just aluminium. Aluminium must be only a shell with kevlar or some other composite sandwiched inbetween it. Betcha Denny Hansen would know.
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Old February 23, 2009, 01:43 AM   #5
Bill DeShivs
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I doubt casting is the way to go. It will be very difficult to get consistent thickness, and just plain aluminum won't stop much in the way of bullets.
I'm sure those shields are made of hardened aluminum sheet and kevlar.
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Old February 23, 2009, 02:38 AM   #6
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...I would question the average man's ability to hold on to the thing when it is hit by a round.
Assuming the plate weighs more than the rifle that fired the round then given the way that conservation of momentum works holding the plate when it's hit is going to be easier than holding onto the rifle that fired the round.
Quote: thick the aluminum must be to stop a .223.
Impractically thick. As pointed out, it's going to take more than just a thick piece of metal to stop rounds if you expect this to be something that a person can lift.
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Old February 25, 2009, 10:46 AM   #7
Double J
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Rough guess this shield will weigh around 300 pounds. Probably 4'' thick. Now, how about side and rear protection? Be afraid....very afraid.
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