I am kinda curious. There are huge MIM holy wars on the internet.  And I will certainly agree that the best forged part beats the best of about anything else.

But there is also such a thing as overkill.  And, as Ruger has shown, the best investment cast parts are as good as the average forged part for frames, slides, etc.  And I gotta think there are plenty of parts in a typical gun where a good MIM part has a life that is longer than it's more abused cast/forged siblings in higher wear areas.

What has brought this to my mind is my Tisas GI 1911 clearly has a MIM hammer.  It have had no issues so far, with probably 250 rounds down the pipe.  But my FUDD hairs twitch a bit every time I notice the injection molding marks on the side of that hammer.

So, has anyone here had a MIM part fail in your own gun?

I was always bum-fuzzled how Ruger could use cast pistol frames, yet Olympic Arms got raked over the coals for having ONE AR model that used cast receivers.

It took years to convince some of the internet folks that the rest of their models were forged.  Lots of people like to regurgitate what they heard online, regardless of how wrong it is.

Sadly, not much has changed in the grand scheme of things.  The CDC voted unamimously today to "encourage" schools to require covid vaccinations from 5 years old and up.

Hey Sqlbullet, I suspect there is some variation on how well some companies have mastered the MIM process. About 15yrs ago I bought a Kimber TLE II, in 45acp, with an aluminum alloy frame and left all the MIM parts in the gun. My purpose was to see how durable the alloy frame and the MIM parts would hold up to competition shooting. At that time I was going to a bowling pin shoot every Thursday and a steel shoot at least once a month. There were quite a few practice sessions in between, as well.

I should also mention, I cleaned it any time more than 100 rounds went through it. The rails were always lubed with Tetra grease. CLP was used for everything else.

10s of thousands of rounds later and no issues whatsoever. The rifling in the barrel is getting a little light, but all original MIM parts are fine and the frame far exceeded my expectations. I still shoot it all the time and have introduced many new shooters with that gun.

How Tisas has done with MIM, I don't know. If it really nags at you, replace it. I doubt that would be an issue for you.

FWIW, the only 1911 hammer I've ever seen broken was a forged hammer. It had the telltale little brown spot from a forging crack and large grain structure.

No, never a problem.

I have a Sarsilmaz K245, that I love.  But it does have some MIM parts in it.

When EAA was stopping importing them several years ago, I didn't know if they would ever be brought in again, so I called up EAA and purchased several parts that I may need going forward.  Extractors.  Misc. springs.  I also purchased a trigger bar assembly too.

The trigger bar was reported as one of the parts that had broken and so far as I know is a MIM part.  Granted, I only saw a single report of it occurring online, so how often it happened, is yet to be seen.  But, I do have a replacement if I ever need it. 

That's my favorite 45acp handgun bar none.  I really enjoy shooting that gun.

My Sarsilmaz SAR9 is one of my favorites as well, for something like 220, you can?t beat it with a stick, and the trigger has actually become tolerable after a few thousand rds

For sure my SIGs and S&W revolvers have MIM parts and probably many others, too.  Never had a part break.  MIM parts, when properly designed and molded hold up extremely well. 

No problems yet. I'm not expecting any issues going forward.

To answer the question straight up... yes  I finally broke a part inside my S&W model 60 J frame in 2017.  This gun was brand new in 1999 right after the swap to MIM parts.
  But I think someone above touched on something, I think it really depends on the part and original design.   I knew several old school LE guys that went through the revolver to polymer transition in LE.  These guys shot their revolvers a lot because it was their sidearm and had to practice and qualify with it.  Most will tell you a pre MIM S&W went from a 25K rd gun down to 5K gun when they went to MIM.  But these are the guys that still shoot their revolvers and ran them hard.
  But for a 1911 and MIM parts, I've personally never worked on one that I could blame on broken MIM parts.

Steve

I?ve only had one MIM part fail. That was an ambidextrous safety on a Rock Island 1911 that apparently was put together using a reverse dovetail where the two halves joined. The harder I tried to get it apart, the tighter it became. I finally broke it to get it apart.
But, that was not the fault of the MIM process or the part.

Once. Was one of the early Kahr K9's when it was still pretty new. The slide back broke in half but stayed in place. Kahr sent me a free replacement (also MIM) after I sent them a photo in an email. That part is still in there after thousands of rounds. Pretty obvious that ht e original part was not typical but defective.