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Thread: Extractor pins

  1. #1
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    Extractor pins

    The proper material for extractor pins is S2 tool steel. The problem is, Carpenter does not make it anymore, unless you order 25,000 lbs.

    Because it is so expensive to acquire, it seems most companies substitute S7, which is readily available.

    Problem is, S7 is not as strong:

    S2 Yield Strength = ~300ksi
    S7 Yield Strength = ~220ksi

    It is extremely likely that Colt uses S2. I know AAC uses S2. I am not sure who else, but if anyone really wants to know, you can collect samples and pay for testing - that is the kind of thing that could make gun magazines great - if they actually reviewed guns.

    I bet the results would be surprising as to who uses what.

  2. #2
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    To be perfectly honest I'm more worried about a cam pin wearing out before and extractor pin.

    And have you ever seen an extractor pin fail, bend, or break before the bolt gave out due to fatigue? Excluding cases of KB's due to whatever reason.

    From some of your posts, I almost wonder if you plan on starting a business as a steel distributor. Distributing all those crazy hard to find steels that no body needs enough of to justify purchasing a 25,000 pound lot.

  3. #3
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    Have there been any issues with extractor pins lately?
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    Maybe we could do a group buy. 25000 pounds of steel would make about 7,000,000 pins give or take a pin or two. Figuring a cost of $10 per pound a pin would only cost about $0.035 for the metal, maybe another $0.035 for fabrication, say seven cents a pin. Cheap. I'll take two dozen.

  5. #5
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    I have seen a few of them tweak or bend. But, in the bigger scope of things I don't know how important it is. It's always a good idea to keep things like this on hand.

    Quote Originally Posted by An Undocumented Worker View Post
    To be perfectly honest I'm more worried about a cam pin wearing out before and extractor pin.

    And have you ever seen an extractor pin fail, bend, or break before the bolt gave out due to fatigue? Excluding cases of KB's due to whatever reason.

    From some of your posts, I almost wonder if you plan on starting a business as a steel distributor. Distributing all those crazy hard to find steels that no body needs enough of to justify purchasing a 25,000 pound lot.



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  6. #6
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    S7 is probably good enough to not have any problems and I have not heard of any. I picked S2 for AAC pins because I felt it was worth it to use the best material known. The govt uses it because it is in the TDP. It makes me wonder how many "MPI" bolts use S7.

    As for cam pins breaking - we engineered around that - our cams pins have lower stress levels and I would not expect one to ever break.

  7. #7
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    I have seen but few extractor pins break. I'd have thought years ago when D-Rings started to became de rigueur that, if extractor pins were already stressed to near the edge, that increasing extractor tension by XX% would cause many more to break. They seem to be adequately sized for the application, is my conclusion...... and/or adequately sized so that the dif between S2 and whatever else is not critical. Just at a glance, I view the span of the pin, in other words the width of the cut for the extractor, as proportionally OK to the size of the pin.

    Not to say there are not bad pins.... since there's bad everything else, there surely are bad extractor pins. I've seen at least one that was simply 1/16 too short. I've seen maybe two that were broken (and as I recall no effect on function) and one that was soft enough to have been bent slightly (again, no effect on on function).

  8. #8
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    Quote Originally Posted by An Undocumented Worker View Post
    And have you ever seen an extractor pin fail, bend, or break before the bolt gave out due to fatigue?
    Yes. In my gun.
    "You people have too much time on your hands." - scottryan

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    So the real question is, who besides Colt, and AAC use S2 tool steel for their extractor pins?

    Next, does anyone besides Carpenter make S2?


    Are there any steel distributors that supply the steel in sane quantities for the smaller firearms manufacturers out there?

    While I appreciate RSilvers for pointing out this finer detail of making a quality AR, he makes it sound like getting the proper steel is damn near impossible. There have to ways manufactures get the steel they need in smaller lots without breaking the bank.

  10. #10
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    Are there any steel distributors that supply the steel in sane quantities for the smaller firearms manufacturers out there?
    I think that is the correct question.
    My brother saw Deliverance and bought a Bow. I saw Deliverance and bought an AR-15.

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