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  1. #31
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    Quote Originally Posted by WHSmithIV View Post

    All anodizing does is align the surface molecules of either the machined billet block or the forged block after it's been machined in order to provide surface hardness to generally 1/10,000th of an inch.
    Hard coat anodizing, which is basically what all parts are done with in the firearms industry, is much thicker. A good anodizer lets you specify the thickness, which is normally one or two thousandths of an inch (not ten-thousandths), with half being buildup on the outside of the part, and half going into the aluminum. This is very important because the tolerances on each part can change significantly. The fact that it builds up into the aluminum is also why it's so durable.

    Anything you see that isn't black, elephant gray (6061 with no dye), or light bronze (7075 with no dye), is probably not hard coat, and will not be very durable. All those little magazine releases in rainbow colors are not hard coat anodized, for instance.
    Last edited by Slippers; 14 July 2015 at 05:09.
    Will - Owner of Arisaka LLC - http://www.arisakadefense.com

  2. #32
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    Quote Originally Posted by JoshAston View Post
    Fairly certain AIM's BCGs are made by Toolcraft. I'd rather have a JP LMOS for a hard use rifle, but the AIM will serve the majority of shooters just fine.
    I don't know if they're Toolcraft or not but Cryptic Coatings also uses Toolcraft. I agree that the price will make you have doubts about what you're getting, but I can say that I've had nothing but great service and products from Aim Surplus. Not saying whether or not this is a good BCG, but I do think it's a good deal. Here is the description on the BCG from them:

    AIM AR/M16 .223/5.56 complete Bolt Carrier Groups. We are having these bolts manufactured to our exacting standards with no Frills added to be able to offer the best BCG at the Best Price! Features 9310 Bolt Material; 8620 Chrome lined carrier and gas key; Properly staked Investment cast gas key hardened to USGI specifications fastened with Hardened Grade 8 Fasteners; Shot peened MPI (Magnetic Particle Inspected) Bolt. Extractor includes Black Insert.
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  3. #33
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    Quote Originally Posted by Slippers View Post
    Hard coat anodizing, which is basically what all parts are done with in the firearms industry, is much thicker. A good anodizer lets you specify the thickness, which is normally one or two thousandths of an inch (not ten-thousandths), with half being buildup on the outside of the part, and half going into the aluminum. This is very important because the tolerances on each part can change significantly. The fact that it builds up into the aluminum is also why it's so durable.

    Anything you see that isn't black, elephant gray (6061 with no dye), or light bronze (7071 with no dye), is probably not hard coat, and will not be very durable. All those little magazine releases in rainbow colors are not hard coat anodized, for instance.

    Anodizing doesn't 'go into the aluminum'. The electrolytic process of anodizing realigns the surface molecules (which also causes the color change to black from the chemical reaction of the acid with the aluminum). It is the alignment of the surface molecules of the metal that hardens it and makes it stronger. The longer you leave a part in an anodizing tank, the deeper the surface will be anodized. Keep in mind, whether it's 1 thousandth of an inch or 2 or even one 10 thousandth, it is only that depth of the surface molecules being realigned.
    Freedom is NEVER Free. We have to work to protect it and even be willing to die to protect it.

  4. #34
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    Getting way off topic but oh well.

    You get a build up of the oxide on the outside as well as penetration into the part. Hence the phrasing - going into the aluminum.

    With regards to MIL-A-8625 Type III Class 2 hard coat anodizing, which is what we're talking about for AR15 parts, you get some color change without dye (which would be Class 1), but it's only going to look black like we expect it to if dye is applied after the part comes out of the acid bath, since it is very porous before it's sealed.

    Fun fact - leave a black anodized part outside in the sun for a year or so and it turns brown as the dye breaks down.
    Last edited by Slippers; 14 July 2015 at 04:52. Reason: Clarifying
    Will - Owner of Arisaka LLC - http://www.arisakadefense.com

  5. #35
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    Will,

    You've copied and pasted this before.

    Maybe when a manufacturer like Slippers who actually does this for a living, speaks you should listen.

    Try to stay in your lane.


    Quote Originally Posted by WHSmithIV View Post
    I'll try to dispense with something for the difference between billet and forged. Ounce for ounce, machined forged 7075 aluminum is stronger than machined billet 7075 aluminum (I worked in an aluminum factory - Nordic Aluminum - for some years). To make up for this, billet parts will usually have some extra strengthening machined into them. For forging, the metal is compressed into the machinable block of material. That compression creates grain lines in the metal .

    When aluminum is melted in the foundry, it is melted into round bars a foot in diameter and generally about 10 ft long. Either billets (blocks) are cut from this bar and re-melted to be forged OR, they are machined directly.

    So, what actually happens? In the re-melting and forging, the melted metal is pressed into a block under pressure that is then cooled for later machining. The advantage of this is that you can feed the entire 10ft. long bar into a furnace like is done for extruding aluminum and simply send the molten aluminum into pressure forms for the desired size block to be machined and you can mass produce thousands of blocks quickly. The pressure used for forging blocks aligns the aluminum molecules into grain lines (smaller than the eye can see) and because of that, the alignment of the molecules provides for some extra strength. For the billet block, you are cutting from that 10 ft. rod into block sizes. It's more time consuming and more expensive to do so. Those 10 ft. rods weren't made under pressure either so there are no grain lines created by the pressure of forging.

    The overall difference is simply that the forged block is a little bit stronger but, because it has those grain lines inherent in the block, it's finish will be just a tiny bit rougher (and we're damn near getting close to microscopic here). The billet block that was cut direct from the rod will have a smoother surface for the machined part.

    All anodizing does is align the surface molecules of either the machined billet block or the forged block after it's been machined in order to provide surface hardness to generally 1/10,000th of an inch. That's an electrolytic process and for color, generally a dye is introduced into the acid solution used for the anodizing. Anodizing with no dye will still change the surface color of the aluminum and that happens due to oxidation during the electrolytic process of anodizing.

    So, the bottom line is that the forging process is cheaper for mass production of machinable blocks of aluminum, and the forged blocks are actually a bit stronger than the the billet blocks cut from the base rod. Their finish won't be quite as satin smooth is all.

    This in no way detracts from billet parts. The strength difference is very small. Functionally, both are equivalent.

    I do not see the point in paying double or triple or more for a metal part just because the surface of it is a little more satin smooth than a perfectly machined part from a forged block that is metalurgically actually stronger.

    My rifle has billet receivers. It has a matched set of Phase 5 receivers. My (almost complete) 7.62x39 pistol has a forged Anderson receiver. Visually, it is next to impossible to really see any difference from over about 1-2 ft. If you look close, you can see the difference in surface finish, but you have to be REAL close. I can feel a slight tactile difference too with my fingers. It's a very small difference, but it's there and it's only because of the difference in the two metal manufacturing methods.

    Just a side note. NEVER buy anything that is cast made. What happens with a cast part is that the molten metal is poured into a mold then simply let to cool or even cooled fairly quickly. This is REALLY bad for most gun parts. Because no pressure was involved to forge the part (and that certainly wouldn't work very well for something like a receiver either - they NEED to be machined from a block), there are stronger and weaker areas in the casting. No uniformity at all.




    What a billet cut does provide is a better finish to the aluminum. Since the forging aligns the metal to

  6. #36
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    We need to trow this in to the T&E program


    Never mind sold out
    Last edited by toolboxluis00200; 15 July 2015 at 13:53.
    $300 and 10 Pastrami Sandwiches and a case of Diet Coke. ( UWone77)

  7. #37
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    We already have a lot of items in the T&E program waiting on reviews.
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  8. #38
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    Quote Originally Posted by GOST View Post
    We already have a lot of items in the T&E program waiting on reviews.
    Yes we do.

  9. #39
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    Quote Originally Posted by GOST View Post
    We already have a lot of items in the T&E program waiting on reviews.
    It was a joke
    $300 and 10 Pastrami Sandwiches and a case of Diet Coke. ( UWone77)

  10. #40
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    Quote Originally Posted by toolboxluis00200 View Post
    It was a joke
    Bam! First complete sentence!

    Missing punctuation, but we're making progress!

  11. #41
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    Aim Surplus AR Foundation Kit

    Awesome.


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  12. #42
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    Quote Originally Posted by toolboxluis00200 View Post
    It was a joke
    Well them jokes to post some reviews.
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  13. #43
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    I didn't copy and paste it UWone, I wrote it from scratch. I thought I had already posted about this before too. Yep, it's getting off topic. Didn't mean to hijack the thread. Slippers is correct that if you leave a black anodized part out in the sun, the color will change. Most anodizing facilities add the dye to the acid bath and most machining facilities parts get sent out for anodizing - it isn't done in house. Extrusion factories often have their own anodizing tanks capable of handling large volumes of 6-8 ft. long extruded profiles. They also do smaller parts. I know several of them. Small part anodizing isn't all that expensive to set up though so I'm sure some companies do their own anodizing.

    The AIM Surplus deal is a good deal whichever way you look at it.
    Freedom is NEVER Free. We have to work to protect it and even be willing to die to protect it.

  14. #44
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    I'll just leave this here...


  15. #45
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    Quote Originally Posted by UWone77 View Post
    Bam! First complete sentence!

    Missing punctuation, but we're making progress!
    Lol. Good one
    $300 and 10 Pastrami Sandwiches and a case of Diet Coke. ( UWone77)

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