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Thread: BCM GUNFIGHTER Mod 6?

  1. #31
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    This might be a good answer to the roll pin problem:

    http://www.spirol.com/library/sub_ca...ex_Pins_us.pdf

    Paul - maybe you could sell them in packages of say 10pc to upgrade your existing handles?

  2. #32
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    Quote Originally Posted by BravoCompanyUSA View Post
    That actually was my original design. Eric (VLTOR) was 10 times better. I dropped mine, and built the VLTOR design.

    Reasons:
    All the stress is still on the pin and that part of the latch and handle.
    The energy still remains at the pin, and the further you pull the extended latch back the more the latch and handle actually work to pull apart from each other.
    So, you still end up driving the charging handle to the rear (not directly) but outboard (right handed shooter).
    My first design was a bandaide. This design was really the correct way.

    Thanks!
    Understood, thanks for clarifying!


    -B
    RIP, Jeff Dorr: 1964 - July 17, 2009


    "When young men seek to be like you, when lazy men resent you, when powerful men look over their shoulder at you, when cowardly men plot behind your back, when corrupt men wish you were gone and evil men want you dead . . . Only then will you have done your share." - Phil Messina

  3. #33
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    Tomorrow I’m finishing up an EAG Tactical Carbine Operators course. Up until today I have been running a PRI CH, with the RTV sealant mod, in my LMT SBR and I have always gotten a fair amount of gas in my face. Well today I acquired a BCM Gunfighter Mod 3 CH and ran the SBR suppressed all day. I noticed a significant reduction in the amount of gas blow back when using the Mod 3 CH and it makes it more pleasurable to shoot.

    Paul I think you are onto something.

  4. #34
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    Just ordered 2 medium GF'r charging handles....


    Im a huge fan of the PRI Big Latch so we'll see how this goes!

  5. #35
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    Smile

    Quote Originally Posted by BravoCompanyUSA View Post
    That actually was my original design. Eric (VLTOR) was 10 times better. I dropped mine, and built the VLTOR design.

    Reasons:
    All the stress is still on the pin and that part of the latch and handle.
    The energy still remains at the pin, and the further you pull the extended latch back the more the latch and handle actually work to pull apart from each other.
    So, you still end up driving the charging handle to the rear (not directly) but outboard (right handed shooter).
    My first design was a bandaid. This design was really the correct way.

    Thanks!
    Oh, I concur. To clarify things I'd add a solid pin to YOUR CURRENT design. I've also seen steel charging handles, too. I think DPMS is the company and they are sold via Brownells. For the same thickness/volume steel would be/could be (using proper alloys) stronger than aluminum. I'm thinking: Your latch in a steel charging handle with a solid roll pin.

  6. #36
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    The BCM charging handle is aluminum, is it not? Wasn't it already determined that sticking with aluminum would be the best bet to prevent galling of the aluminum by a steel charging handle?

    However, if someone makes an aluminum solid pin of that size, I'm not sure I could think of an argument against it...


    -B
    RIP, Jeff Dorr: 1964 - July 17, 2009


    "When young men seek to be like you, when lazy men resent you, when powerful men look over their shoulder at you, when cowardly men plot behind your back, when corrupt men wish you were gone and evil men want you dead . . . Only then will you have done your share." - Phil Messina

  7. #37
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    Aluminum against steel is a much more "friendly" combination than aluminum against aluminum. The basic problem is that split roll pins are not intended to be bearings for rotation. They are not very round and by design they are a force fit, not a clearance fit as bearing pins are.

    Actually, I think the problem with shearing roll pins with after market latches is the inertia shock load that occurs when the handle slams forward - not the retraction of the handle. Any increase in the weight of the latch particularly if it is extended further outboard increases the shear force and shock load on the roll pin.

  8. #38
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    Quote Originally Posted by DBR View Post
    Aluminum against steel is a much more "friendly" combination than aluminum against aluminum. The basic problem is that split roll pins are not intended to be bearings for rotation. They are not very round and by design they are a force fit, not a clearance fit as bearing pins are.

    Actually, I think the problem with shearing roll pins with after market latches is the inertia shock load that occurs when the handle slams forward - not the retraction of the handle. Any increase in the weight of the latch particularly if it is extended further outboard increases the shear force and shock load on the roll pin.
    Two things.

    First, I think that the pins are shearing on extended latches because they cease to be the pivot point when the latch is pulled back past a certain point. Once the pivot point changes the pin is under shear stress.

    Second, the BCMGF removes the possibility of this happening by filling in the back side of the CH so that the latch cannot over-rotate and the pin always remains the pivot point thereby eliminating the stress.

    If people think that a solid pin would be better they are certainly welcome to change out what's there, but I think the roll pin is being used in it's correct application in the BCMGF. If I was really paranoid I might take a piece of piano wire of the right diameter and bang it into place inside the roll pin that's there now. I won't be doing that personally, but it's about the most I'd do.

  9. #39
    +1 Rob,

    ... and a couple of "fun facts".

    The pin in the BCMGUNFIGHTER Charging Handle is the real milspec roll pin (same as used in the standard BCM Charging Handle, as well). Its shear strength is rated at almost double that most commercial (mostly chicom) roll pins sold in the US. There is a small volume of certifications from material composition, plating, dimentions, shear sample testing that comes with every batch. And they cost more than twice the price of regular roll pins. (there are a lot of these types of 'fun facts'/details on various BCM produts, but we just haven't discussed it much) So the pin is actually significantly better than a HUGE percentage of the charging handles in the commercial market.

    But with the BCMGUNFIGHTER Charging Handle redesign, the stress on it is really no more than Eugene Stoner expected to be on it. Thats the genius the of Vltor design. I have never seen a pin break on a standard latch. And if it did, I would be 100% sure, it wasn't a stress issue - it was a substandard crappy pin.
    .


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  10. #40
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    Quote Originally Posted by rob_s View Post
    Two things.

    First, I think that the pins are shearing on extended latches because they cease to be the pivot point when the latch is pulled back past a certain point. Once the pivot point changes the pin is under shear stress.

    Second, the BCMGF removes the possibility of this happening by filling in the back side of the CH so that the latch cannot over-rotate and the pin always remains the pivot point thereby eliminating the stress.

    If people think that a solid pin would be better they are certainly welcome to change out what's there, but I think the roll pin is being used in it's correct application in the BCMGF. If I was really paranoid I might take a piece of piano wire of the right diameter and bang it into place inside the roll pin that's there now. I won't be doing that personally, but it's about the most I'd do.
    Agreed, Rob. However, if one pulls hard enough (we should not be, however) there will still be some shear on the roll pin.

    I'm an "Armaggeddon"-type engineer: things should not fail. Ever. So I like overkill. Kinda like the Swiss, I guess.

    P.S.

    I like the piano wire idea!

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