Remington 870 Express MIM Extractor Issue

Discussion in 'Technical Questions & Information' started by Snakedriver, Jun 2, 2009.

  1. Snakedriver

    Snakedriver Active Member

    Mar 4, 2009
    SW. Florida
    OK, so I have a tough question for all you Remington 870 gunsmiths and armorers. Several hours of research on the Internet last night failed to resolve the issue of the quality of the MIM extractor on the new 870 Express models that are being made these days. Are they inferior and subject to failing??? Should they be replaced? The Remington website was no help at all. Midway sells three different extractors for the 870 12 Ga.: The one noted as 870 Express, manufacturer’s model number F99046 for around $8.50 that I assume is MIM, the one noted as 870 Marine Magnum, manufacturer’s model number 97597 for around $10.50 that appears to be stainless steel or chromed steel and the one just noted as 870 manufacturer’s model number F16176 for around $13.50 that must be the forged steel version. The problem with the Midway website doesn’t give any description of the material used and a web search of the manufacturer’s part number doesn’t reveal anything either.

    I have the Remington 870 7-shot Tactical model #25077 that seems to be somewhat of a hybrid, but I assume it’s a stealth Express with the MIM extractor. Just to be safe I ordered an extra 870 extractor, plunger and spring from Midway all described as for the 870 Marine Magnum for my parts kit. They all appear to either forged steel in chrome or s.s. and not MIM. Some sites on the Internet claim the Marine Magnum is just a nickel coated Express model with the same MIM parts as the regular Express version, but I don’t think so.

    What is your opinion of the Express MIM extractor issue? Is it being overblown or is it real? Should I change out the extractor that came in my gun now, or just hang on to it in my extra parts kit? Does anyone know the skinny on the Marine Magnum’s construction and what the parts (especially the extractor) are made of? :confused:
    Last edited: Jun 2, 2009
  2. RJay

    RJay Well-Known Member

    Feb 22, 2004
    Goodyear, Arizona
    There may be those who disagree ( which is why there are more than one flavor of ice cream ) but in my experience the durability of MIM parts is a non Issue.:)
    They are used in military firearms, critical aircraft applications, NASCAR, NASA, you name it. I personally have never seen any more failure of MIM parts than of forged parts.

  3. Snakedriver

    Snakedriver Active Member

    Mar 4, 2009
    SW. Florida
    That's good to hear! On the Internet last night I saw where someone else said something similar in that in his opinion the MIM parts were better and would wear better than the standard forged steel parts. Since Remington went to the MIM parts as a cost savings measure, I guess everyone just assumes that the more costly forged steel extractors are better. Thanks for your thoughtful response! I think I'll just keep the replacement parts I bought in my parts kit for now, it won't hurt to have a spare. The gun functions flawlessly so it's not like I have any real issues, I was just curious for someone's opinion. :)
    Last edited: Jun 3, 2009
  4. Mark

    Mark New Member

    Jul 1, 2006
    MIM is metal injection molding. Properly done, it produces a good part.

    The whole matter of MIM part failure are the issues of part design, porosity, and voids. Part design is simply a matter of having no sharp internal corners on the part. A sharp corner will invite cracking and part failure. For that matter, a forged part will crack at a sharp corner.

    Porosity and voids will cause a part to fail. These are inherent with any injection molding operation. These are caused by an improperly vented mold, or poor mold design which allows air to become trapped in the part. Where ever this air is trapped, the part is weaker.
    It has been said that if an MIM part doesn't break right away, it will last forever. This is not true. If a part has porosity or voids, it is only a matter of time before the part will work harden, become brittle, and break. A forged part will work harden also, but because this part is solid, it won't break. The molding defect rears it's ugly head.
    This is where MIM gets it's bad reputation.

    The key to making good MIM parts is checking parts for dimensional integrity, proper appearance, and weight. The weight of the part will tell you if the part is solid.

    Sooooo, what are the toolmaker, molder, heat treater, and quality control people doing? Are they working in concert? Does each understand their function? Are they backing each other up, or pointing fingers?

    Done properly, MIM produces a good part.

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