MIM Gun Parts?

MIM Gun Parts?

This is a discussion on MIM Gun Parts? within the General Firearm Discussion forums, part of the Related Topics category; Hello, I learned about MIM, casting, forging, etc in college a while back. MIM and casting always seemed to have about the same weaknesses in ...

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Thread: MIM Gun Parts?

  1. #1
    Senior Member Array Joshua M. Smith's Avatar
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    MIM Gun Parts?

    Hello,

    I learned about MIM, casting, forging, etc in college a while back.

    MIM and casting always seemed to have about the same weaknesses in my mind.

    After ordering and installing this MIM safety on my 1911, I got to taking a hard look on what's NOT forged in modern firearms.

    Turns out, almost everything in non-custom guns is MIM. Armscor uses MIM frames (Armscor makes these for STI, RIA, and until recently, Charles Daly). Kimber is pretty much all MIM. Wilson uses MIM.

    Remingtons have a lion's share of MIM parts and the company owns its own MIM plant.

    Smith and Wesson revolvers are using MIM parts internally.

    Colt uses MIM.

    Ruger, if I read right, uses cast frames and slides with MIM internals.

    They all hold up well. Yet people hate MIM.

    Why? And what are your experiences with MIM?

    I personally had ONE MIM part ever break on me. It was a joint on an ambi safety from first year Charles Daly 1911 production, and it had an obvious flaw. In other words, it was a goofed step in the process, not the process itself.

    So, what are your feelings on MIM? Are they functional? Have they made all our firearms into crap?

    Josh <><


  2. #2
    Senior Member Array Shizzlemah's Avatar
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    I can say that there are still lots of cast parts in firearms.

    Ruger owns one of the biggest (if not the biggest) foundry in New England. I am 100% positive that they cast a boatload of metal.

    The manufacturer up the road from me is 100% cast, no MIM.

    I know casting fairly well, and don't know a whole lot about MIM. Had the opportunity to work at a MIM shop but figued I didn't know enough to offer... But everything I have heard is that MIM is a black art.

  3. #3
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    So, what are your feelings on MIM? Are they functional? Have they made all our firearms into crap?

    I avoid them when possible
    Yes, they're functional
    No they haven't made firearms crap.

    Forged will last longer over the long hall, with a lot less chance of breaking if actually used enough. For the majority of shooters who don't put 10K through any of their guns in a lifetime, MIM should be no issue. Others who actually shoot a lot year after year may get to see how inferior MIM is to forged.

    Brownie
    The mind is the limiting factor

    Quick Kill Rifle and Pistol Instructor

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    Senior Member Array Joshua M. Smith's Avatar
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    20,000 or so round though my Taurus 92, no failures save for one locking block...

    I'm mainly concerned about the longevity of my Kimber ambi safety. It looks and feels cheap, but doesn't act cheap, if that makes any sense whatsoever.

    Josh <><

  5. #5
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    Metal investment castings are not MIM.

    They are two totally different fabrication processes and are in no way related to one another.
    Just FYI.

    They also do not share the same weaknesses.

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    Senior Member Array Joshua M. Smith's Avatar
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    QKShooter,

    The main weakness I've seen in both are voids in the metal, weakening it.

    I'm aware they aren't the same process.

    Josh <><

  7. #7
    OD*
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    I believe Armscor uses cast frames.
    Ray Witham Jr.- Email: raywjr@armscor.net
    Ivan J. Walcott - Email: ivan@armscor.net
    "The pistol, learn it well, carry it always ..." ~ Jeff Cooper

    "Terrorists: They hated you yesterday, they hate you today, and they will hate you tomorrow. End the cycle of hatred, donít give them a tomorrow."

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    Member Array Emahevul's Avatar
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    For those of us who don't know the difference (not being a metal worker after all) could someone give a quick explanation of the difference between forged/mim produced weapons and what the believed pro's/con's are of the 2 different processes?


  9. #9
    OD*
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    "The pistol, learn it well, carry it always ..." ~ Jeff Cooper

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  10. #10
    Senior Member Array Joshua M. Smith's Avatar
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    MIM - Metal Injection Molding - Powdered metal is mixed with a polymer binder and heated to create a slurry. The slurry is injected into a mold where it is heated to the metal's melting temperature to bind the metal, then cooled. The part which emerges is larger than than the finished part due to the presence of the polymer.

    The polymer is then removed through heat and/or chemical means, usually in a vacuum, and the now all-metal part is further finished.

    MIM parts can be made to exacting tolerances in great quantities, and it is not the sintered metal from the past, which is where I assume it got its bad name.

    Investment Casting - Somewhat similar to the MIM process, only no slurry is made. Rather, molten metal is poured or forced by centrifugal force or explosion etc into a mold and allowed to cool. The mold is then broken off, or otherwise removed from, the part.

    To me, MIM seems it would be less prone to flaws simply because it's injected under pressure and would (probably) have a lesser chance of getting air voids int the finished product due to that pressure. Just my guess though.

    Josh <><

  11. #11
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    I have no objection to high quality investment cast 1911 frames. They seem to hold up quite well.

    Some older investment cast semi-auto slides had real problems with cracking.

    There are no MIM parts in/on any of my everyday personal protection carry guns.

    It's just a personal quirk of mine that I do not trust MIM firearm parts in general.

    Call me a fool but, no MIM ever for me.

    A range gun having MIM parts would not really bother me.

    I'm not willing to bet my life on Metal Injection Molded gun parts.
    All of my most trusted daily carry firearms pre-date the MIM fabrication process so it's really not been much of a concern for me.

    For sure I would never buy a MIM thumb safety or slide stop or sear or disconnector or hammer.
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    Also STI offers three Colt pattern frames.
    Two are high quality heat treated investment castings but, their standard Colt pattern frame is machined from a forged steel billet and their lightweight alloy frame is forged/CNC Machined.
    Just FYI.
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