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Thread: Idea for easier 80% lower

  1. #1
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    Idea for easier 80% lower

    So I have an idea, you take a plug made of glass that has been modeled in dimensions of buffer tube threading, fire control pocket, holes etc, then you pour steel/aluminum around it, having the proper dimensions to it, then after the customer buys the lower and uses some sodium hydroxide (drain cleaner) to dissolve the glass plug, creating a ready to use lower.

    As I understand it, the melting point of the glass is higher than steel/aluminum so the plug will not melt, I assume the only issue here would be the shrinkage from the metal contracting as it cools?

    Any unforeseen issues with this idea?

    I assume the ATF will give it a no go because they are dicks?

  2. #2
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    Depends.

    If you applied for approval without all the explanation, it probably wouldn't be looked at too hard.

    But I could totally see them going: "So break the glass and it's a firearm? Seems too easy." Without having a good grasp of it anyways.

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    I don't think sodium hydroxide dissolves glass.

    Well guess I was wrong but next question is what does it do to aluminum.

    "Glass is one of the least reactive substances known to chemistry. It is the standard container material for almost all lab chemicals because it's so inert. But there are a couple of substances that have strong reactions with glass. Sodium hydroxide, aka solid drain cleaner or lye, can easily be stored in glass as a solid, but when molten, it reacts violently with glass and can actually dissolve it away! So, the next time you clog up your drains with broken glass beakers and flasks, rest assured your household drain cleaner has what it takes."
    Last edited by mack7.62; 04-09-20 at 19:24.
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    Quote Originally Posted by HeruMew View Post
    Depends.

    If you applied for approval without all the explanation, it probably wouldn't be looked at too hard.

    But I could totally see them going: "So break the glass and it's a firearm? Seems too easy." Without having a good grasp of it anyways.

    Well you could "break it" but it is still there, and likely will be as solid glass in such a configuration would be very hard to break and remove, that is why development via chemicals was selected as the desired method.

    But then again I thought of this idea around 2 days ago so its a bit in the air.



    Quote Originally Posted by mack7.62 View Post
    I don't think sodium hydroxide dissolves glass.

    Well guess I was wrong but next question is what does it do to aluminum.

    "Glass is one of the least reactive substances known to chemistry. It is the standard container material for almost all lab chemicals because it's so inert. But there are a couple of substances that have strong reactions with glass. Sodium hydroxide, aka solid drain cleaner or lye, can easily be stored in glass as a solid, but when molten, it reacts violently with glass and can actually dissolve it away! So, the next time you clog up your drains with broken glass beakers and flasks, rest assured your household drain cleaner has what it takes."
    Sodium aluminate is also formed by the action of sodium hydroxide on elemental aluminium which is an amphoteric metal. The reaction is highly exothermic once established and is accompanied by the rapid evolution of hydrogen gas. The reaction is sometimes written as: 2Al + 2NaOH + 2H2O → 2NaAlO2 + 3H.


    So I assume we need the proper alloy, to prevent this, or maybe just use steel.

    I am also not sure why no one else has done this before.
    Last edited by Groyper; 04-09-20 at 19:58.

  5. #5
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    So here's the thing: 1) lowers are forged, not cast. Regardless I wouldn't touch a cast AR lower if it was the last on earth. 2) If you're casting aluminum around glass it doesn't matter what the melting temp is, the glass is going to crack or expand, especially with small details like FCG and selector holes. 3) Most glasses are extremely inert when they encounter NaOH even in extreme concentrations (as an aqueous solution.) As mack7.62 pointed out above molten NaOH will react with glass, but also consider the melting point of NaOH is north of 600 degrees Fahrenheit, well into the range Aluminum begins to become pliable. It won't work. Don't let the good idea fairy bite too hard next time.
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    Quote Originally Posted by Leonidas24 View Post
    So here's the thing: 1) lowers are forged, not cast. Regardless I wouldn't touch a cast AR lower if it was the last on earth. 2) If you're casting aluminum around glass it doesn't matter what the melting temp is, the glass is going to crack or expand, especially with small details like FCG and selector holes. 3) Most glasses are extremely inert when they encounter NaOH even in extreme concentrations (as an aqueous solution.) As mack7.62 pointed out above molten NaOH will react with glass, but also consider the melting point of NaOH is north of 600 degrees Fahrenheit, well into the range Aluminum begins to become pliable. It won't work. Don't let the good idea fairy bite too hard next time.
    All of this. It wont turn out how you think.
    Milling them is way easier and safer.

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    Quote Originally Posted by MegademiC View Post
    All of this. It wont turn out how you think.
    Milling them is way easier and safer.
    BUT I DONT WANNA!



    Quote Originally Posted by Leonidas24 View Post
    So here's the thing: 1) lowers are forged, not cast. Regardless I wouldn't touch a cast AR lower if it was the last on earth. 2) If you're casting aluminum around glass it doesn't matter what the melting temp is, the glass is going to crack or expand, especially with small details like FCG and selector holes. 3) Most glasses are extremely inert when they encounter NaOH even in extreme concentrations (as an aqueous solution.) As mack7.62 pointed out above molten NaOH will react with glass, but also consider the melting point of NaOH is north of 600 degrees Fahrenheit, well into the range Aluminum begins to become pliable. It won't work. Don't let the good idea fairy bite too hard next time.
    So any way a cast AR lower would work?
    Last edited by Groyper; 04-09-20 at 22:39.

  8. #8
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    Quote Originally Posted by Groyper View Post
    BUT I DONT WANNA!





    So any way a cast AR lower would work?
    Not really. With casting you risk air pockets being trapped inside the aluminum as it cools. It is a far more involved process to cast something than forge it. Even after aluminum is cast in ingots for sheetmetal production (for instance) the metal is then hot rolled or cold rolled out into a sheet thereby changing the physical properties of the metal to something more akin to a forged material. Additionally with a forged lower the outside dimensions, i.e. the overall width, length (to an extent), and major surface features are established during the forging process.
    In heavenly love abiding, no change my heart shall fear;
    and safe is such confiding, for nothing changes here:
    the storm may roar without me, my heart may low be laid;
    but God is round about me, and can I be dismayed?

  9. #9
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    Quote Originally Posted by Leonidas24 View Post
    Not really. With casting you risk air pockets being trapped inside the aluminum as it cools. It is a far more involved process to cast something than forge it. Even after aluminum is cast in ingots for sheetmetal production (for instance) the metal is then hot rolled or cold rolled out into a sheet thereby changing the physical properties of the metal to something more akin to a forged material. Additionally with a forged lower the outside dimensions, i.e. the overall width, length (to an extent), and major surface features are established during the forging process.
    Would vibrating the container mitigate the risk of an air pocket?

  10. #10
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    Quote Originally Posted by Groyper View Post
    Would vibrating the container mitigate the risk of an air pocket?
    Get off the idea of casting a receiver. Several large manufacturing companies at one point cast AR lowers with expensive machinery and it is viewed entirely as an abject failure. Cast lowers are the pariah of the 90s and early 2000s AR world. Besides this the complex process of heat treating 7075 aluminum alloy becomes a problem. Then after it's heat treated how are you going to correct deformities and warps that are a result of the heat treating process. Just stahp.
    In heavenly love abiding, no change my heart shall fear;
    and safe is such confiding, for nothing changes here:
    the storm may roar without me, my heart may low be laid;
    but God is round about me, and can I be dismayed?

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