Has anyone had any real trouble with MIM?

[AnthonyRSS]

I always hear bad things about MIM parts but have never heard anyone have actual problems with them. I want to know if MIM really is crap. Has anyone had any trouble with the name-brand MIM stuff, like Chip McCormick and the Wilson value-line?

Thanks,
Anthony

[stans]

Well, let's see, the MIM slide stop on my Kimber Gold Match (first series) is very soft and has flat spots worn where the bottom lug on the barrel rides on the stop pin. Seems the MIM grip safety might be a bit on the hard side as the arm that blocks the trigger is now chipped and non-functional. I wonder what will fail next? :mad:

[richg]

How dows one tell the difference between MIM and straight cast parts?

Rich G.

[1911Tuner]

I always hear bad things about MIM parts but have never heard anyone have actual problems with them. I want to know if MIM really is crap. Has anyone had any trouble with the name-brand MIM stuff, like Chip McCormick and the Wilson value-line?

Thanks,
Anthony

Oh yeah...extractors, slidestops, thumb safeties, one grip safety broken in two...a firing pin stop, two cracked sears...

The name brand stuff...Wilson, McCormick, etc...is subject to the same issues as any other, since they are outsourced like all the others...and the quality of an MIM or cast part depends completely on how carefully the process is controlled by the manufacturer.
********************

richg...An MIM part will have a sprue mark somewhere on it. A small circular
or rectangular indent...unless it's been covered by prep and a matte finish such as parkerizing...but sometimes you can see the mark anyway if you look closely enough. Most MIM pops out of the mold finished...bluing and all. Sometimes the coloration looks odd. Blue will be plum-colored or have an
odd tint. It normally has a polished appearance in the areas that show
and less so on the underside...but sometimes even the areas that don't
show look very smooth.

Machining marks are usually evident on machined barstock parts...but some castings are cast oversized and finish machined, and can also show toolmarks.
look at a casting closely, and you can see the porosity that isn't evident on a barstock part.

If well-made, MIM is perfectly suitable for certain applications...but not for all.
The key is the quality of the material and the QA on the process. Parts subject to shock or impact stresses and bending or flexing stresses aren't suitable. Extractors, barrel bushings, and firing pin stops are examples of not suitable for MIM. Grip safeties, thumb safeties, and mainspring housings are examples of suitable...but even those can quickly fail if the material isn't good. Most, if not all of these parts are supplied by the lowest bidder, and is subject to all that implies.

[stans]

Castings also tend to have a plum color when blued.

[gottripletsNC]

removing thumb safety to get into the gun, and the flat part broke away from the stem that goes in the tangs and grip safety, flush at the stem, rendered my gun inoperable for 2 weeks until I could find the part to replace it with.

[stumbler]

I have not had any problems in my guns, but I am constantly changing parts out. And once I have the gun the way I want it, it sits in the safe for a while as I mess with another. Maybe I don't keep parts in long enuff. Not keeping parts in long enuff is detrimental to long term testing:D