I took awhile but now we're completed the holy trinity of Kimber. The crap magazine, the plastic main spring housing and finally the MIM (metal injection molding) parts. I could go on about this but who am I to be believed, I'm just an old man on his computer so I'm going to quote from a piece that was written by long time Wilson Combat Customer Satisfaction Representative, Frank Robbins. Mr. Robbins was tragically killed in a motor vehicle accident on his way to work years ago but as we've all come to learn nothing dies on the internet.
One other thing I forgot to address, MIM parts. A company that I will not name gave the MIM parts a bad name because they had a bad batch of MIM parts. This was many years ago. Since then remarkable things have happened.
MIM parts are extremely dense and very exact. They are much less prone to wear and breakage than a factory Colt, Spfg. etc. part. This is why we use them in our CQB's, etc. Although not quite as hard as our tool steel parts, they will last a very long time. This is why we can still guarantee our total gun, including the MIM parts, for life.
The tool steel parts are actually overkill. The MIM parts last for life (I know of one gun that has over 100,000 rounds thru it and the trigger pull feels the same as it did when new) therefore I guess you could say the tool steel parts lasts for a lifetime and ½.
We use the tool steel parts in our full custom guns. (These are the ones that cost from $2800.00 up) Our full custom guns, Stealth, Tactical Elite, Super Grade and Tactical Super Grade, are not for everyone because of price. They are intended for someone that can afford the very best we can do.
They [tool steel] actually won't last any longer, shoot any straighter or be more dependable than our CQB's, Protectors and Classics, but we spend many extra hours in fitting and prepping them for a perfect cosmetic handgun as well as a great shooter. And because of this, we use the tool steel parts that take longer to fit.
Again, all of us guys here, including Bill Wilson use the very same MIM parts in our guns. And we shoot a bunch! Once installed and fit, no one can tell the difference in the feel of the trigger pull with either type of parts.
Ok, I'm done with my book. Hope this helps too. Just didn't want you all to believe everything you read from self appointed experts.
Frank Robbins Wilson Combat"