Friday, January 14, 2011

Swapping Out the MIM

I need to search the web more, but, if you WERE to swap out parts in your MIM laced 1911 and replace them with better forged stuff, which parts specifically do you go for.

Just supposing.

There has to be a list, somewhere that reads like,

"The following 8 items need to go:
  • slide stop
  • sear
  • extractor
  • etc.
  • "
Heck it might stop at that.

[Update:  MIM is Metal Injection Moulding.  Instead of forming parts by heating a bar of steel red hot and then hammering it into shape, or pouring molten metal into a sand mold, a MIM part sorta is like fancy play-doh with special metal filings in it (this is WAY over simplified).  You form your gun part out of this play-doh then put it in a kiln.  When it heats all the metal bits fuse together and out comes a solid metal part.  The worry is that the MIM kiln work won't have done the job and there will be weaknesses in the metal.  With molten metal you worry about bubbles and voids.  Forging is nice because is aligns the metal molecules (man, true metallurgists are banging their heads on their keyboard now...) and the part is rarely overworked or worked too cold in a factory.  But... with all that fettling forging is EXPENSIVE...  Forging was pretty much the only way 100 years ago.]


    Anonymous said...

    What does MIM laced mean?

    Kirk A said...

    To best answer your question, first ask yourself whether this is for defense or target practice. Your answer dictates a required level of reliability. Then ask, if a certain piece broke, would the pistol be disabled?

    I've already cited my preferred suppliers of 1911 parts, but I'll add something to make your experience even more enjoyable. Purchase and fit an EGW square-bottomed firing pin stop. This is JMB's original pre-A1 design, and it makes it a joy to shoot. Otoh, it will become more difficult to rack the slide; but if this bothers you, you may always cock the hammer first. (Additionally, fitting this precisely will prevent unwanted rotation of the extractor.)

    Tam said...


    Nothing on a name-brand pistol needs replacing.

    There are, however, things I replace because I want to.

    I toss MIM or cast slide stops and replace them with a Greider or a Wilson "Bulletproof".

    If the pistol has a nylon mainspring housing (Kimber, many Colts) or one with a some goofy lock in it (Springfield) I'll install an Ed Brown or Smith & Alexander replacement.

    I have no qualms about tossing all the lockwork and installing Cylinder & Slide parts in its place.

    Again, none of this is necessary.

    New Jovian Thunderbolt said...

    THAT's what I was looking for. A definitive answer with examples.

    And it is in line with my usual plans. I sorta insitinctively did all that with the Sprinfield, except the lockwork. But even a N00b like me can swap a slide stop sorta thing.

    Guffaw in AZ said...

    "Swapping out the MIMS
    Swapping out the MIMS
    We will come rejoicing,
    Swapping out the MIMS!"

    wv: unded

    Old NFO said...

    Tam nailed all the same ones I had, and Ed Brown, C&S and Wilson parts are NOT MIM...

    New Jovian Thunderbolt said...

    I wonder who uses a MIM extractor spring. That would be my second biggest worry after the slide stop. I'd expect MIM lockwork to not fail for a while, but those two...

    Kansas Scout said...

    The question is, what are the failure rates for mim parts? are they high enough to worry about? Especially for us who carry a lot but shoot less often than competition shooters.

    Tam said...

    Old NFO,

    "Tam nailed all the same ones I had, and Ed Brown, C&S and Wilson parts are NOT MIM..."

    Some are cast, though. If you want machined-from-stock, some label reading is necessary...

    And with some parts, of course, you're just Sierra Oscar Lima; I don't know of anybody offhand who makes a machined grip safety, for example, not that it's exactly a high-stress part.

    Tam said...

    Kansas Scout,

    "The question is, what are the failure rates for mim parts? are they high enough to worry about?"

    Not really, no.

    New Jovian Thunderbolt,

    "I wonder who uses a MIM extractor spring."

    Extractor spring? No such part on a 1911; the extractor is its own spring...

    New Jovian Thunderbolt said...

    Right right. I meant that. I meant extractor "made out of spring steel vis made out of MIM." Mea culpa, and thanks for the clarification.

    Old NFO said...

    Concur Tam, but I trust Brown, C&S and Wilson parts because all of them DO stand behind their products and have invested large $$ in their processes.

    Tam said...

    Old NFO,

    The problem is that for a lot of those parts, the companies in question contract out to outside suppliers which may change from year to year.

    Wilson does not have their own casting of MIM facilities on-site, f'rinstance.