# Full size SIS thumb safety snapped in half.



## snookie (Jun 15, 2008)

My new full size SIS thumb safety snapped in half the second time I took it to the range. i had not bought Kibmers in a while because i did not trust the quality of their small parts. But i like the SIS series so much I took a chance. Now I feel like I need to get all the MIM replaced. Thats annoying. Fortunately i know a very good gunsmith who does alot of this kind of work. He even sells new Kimbers and replaces all the MIM out of the box for customers.


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## Baldy (Jun 21, 2006)

Well that sure would ruin your day. Glad you know a good shith as they are worth their weight in gold. Good luck.


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## submoa (Dec 16, 2007)

Get him to lose the Swartz safety while he's at it.


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## 2006sporty (Mar 21, 2008)

*Sis*

I also just got my SIS45.Only got about 100 rds thru it...Let me know how yours turns out.Mine seems to be very accurate.


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## Shipwreck (Jan 26, 2006)

The MIM issue is a hotbed issue. Personally, MIM never bothered me. That being said - MIM parts that Kimber use tend to have more problems than MIM parts that other brands use. I don't read near the complaints about breakage problems in Springfields that have MIM parts as I do about the Kimbers....


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## 2006sporty (Mar 21, 2008)

What the heck is MIM


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## Steve M1911A1 (Feb 6, 2008)

MIM: "_M_etal _I_njection _M_olding."

Sintered (finely powdered) metal, in a liquidous matrix, I believe, is injected into a ceramic mold that is a negative image of the desired part. Heat and pressure are applied, until the sintered metal fuses into the desired part, the liquid fraction acting as a flux. Then the mold is broken open to remove the finished part.
MIM results in a fully finished part, except for a few mold sprues. It does away with most finishing operations, except perhaps final polishing.

The ceramic mold is formed around a wax model of the finished part by merely dipping the wax part into a tub of liquidous clay several times and then letting it dry.
The ceramic clay is fired (hardened) in a kiln, where the wax melts out leaving a negative image of the desired part.

The wax model is cast from hot, molten wax poured into a flexible, permanent, silicone-rubber mold that was formed (by dipping) around a model part made by a machinist or mold-maker.


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## Concealed45_1911 (Jul 4, 2008)

Can I get a more thorough explination Steve ????


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## Steve M1911A1 (Feb 6, 2008)

Concealed45_1911 said:


> Can I get a more thorough explination Steve ????


Yeah. I just sent you a 256-page PM, complete with footnotes and bibliography.
Tell me if it doesn't come through OK.


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## submoa (Dec 16, 2007)

Actually, in the MIM process, a mold is made from steel. Then powdered metal is mixed with a plastic binder. This mixture is then injected into the mold under heat and high pressure to form the part.

There are 2 reasons why MIM is inherently weaker than even cast:

The presence of plastic in the mixture results in voids. Essentially the finished part is made of metal "foam."

In cheaper manufacturing processes, the mixture of metal and binder is not uniform. Areas of high plastic concentration in the mixture produce a 'bubble' that short of xray cannot be seen in a finished part.​
Manufacturers like MIM as it results in a finished product requiring no further machining (no added labor) and allows tighter tolerances in the finished gun. MIM guns look good but are not made for the long haul.

The method described by *STEVE1911* is actually known as Metal Investment Casting or the lost wax process. Additional machining is required after the part leaves the mold. Most metal receivers are made this way (ie, Caspian).


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## 2006sporty (Mar 21, 2008)

*Sis Mim*

Thanks I'm a toolmaker and,have not ran across that abbreavation before. I am also new to handguns.....My SIS seems to be of great quality.:mrgreen:


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## Mike Barham (Mar 30, 2006)

The staff gunsmith at Gunsite recommends replacing all MIM parts on serious pistols. They break regularly in the 1000+ round courses at Gunsite.

While none of the Kimbers in the 250 class I just took actually broke any parts, all of them malfunctioned repeatedly during the course.


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## 2006sporty (Mar 21, 2008)

*Replacment parts*

I would like to do all my own work if possible....What should be replaced and, where can I get the best quility parts?


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## submoa (Dec 16, 2007)

I suggest replacing the barrel bushing, firing pin stop, slide stop, extractor, hammer and sear on Kimbers for better reliability with either tool steel or billet.

Good parts are available from Ed Brown, Wilson Combat, etc.

Carryguns used to have a complete reliability kit for Kimbers with all these parts. I like their ignition kit.

I like AFTEC extractors as they maintain tension better than standard designs over long use.

If you really want to get serious, replace all the pins with EGW's drill rod pin kit.

Actual selection of parts will be dependent on your personal preferences for your gun.


This is not a project for the faint hearted. At the end of the day you will have added $100s of parts and will still be left with a $1,000 gun. Your best bet is to just replace the broken part, sell the Kimber and just buy a gun with no MIM or FPB to start off with (Dan Wesson Pointman 7 starts at about $1k).


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## bill5074 (Jun 23, 2008)

You guys are making me nervous. I have a kimber Ultra CDP II and have not had any problems after about 600 rounds. Are all the parts Submoa was talking about MIM on the Kimbers?? This is the first I have heard of this, and am now having second thoughts. I have had other Kimbers and have had no problems. Should i get rid of the Kimber and replace it with something else?? Thanks for any feedback.


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## submoa (Dec 16, 2007)

Yes, all the parts are MIM.

Depending on your use, you can simply use it until a part breaks and carry on. And you might get several thousand rounds use between part breakage.

One other dubious part of Kimbers is their Series II Firing Pin Block. This uses a pin that pushes up a plunger in the slide when the grip safety is engaged. Aside from the fact Swartz's are sensitive to grip safety alignment, this MIM pin will shear if you have the grip safety engaged when you pull off the slide. Unless you have previously removed the FPB, your Kimber will be inert with a broken Swartz pin.

See my thread for more details on FPBs and MIM: http://www.handgunforum.net/showthread.php?t=14377

What folks often forget is that while 1911s are great guns when tuned and working right, they are also high maintenance... Just like hot women :mrgreen:

The following maintenance schedule is quoted directly from the Wilson Combat 1911 Auto Maintenance Manual by Bill Wilson.

Clean and Lube, Routine:

Lead bullet use every 300-500 rounds

Jacketed bullet use every 500-700 rounds

Carry pistols once a month​
Clean and Lube, Thorough:

Every 5,000 rounds and/or every 3 months your pistol should be completely disassembled, cleaned and lubricated.​
Spring Replacement:

Recoil spring every 2,000 rounds

Firing pin spring every 5,000 rounds

Hammer spring every 25,000 rounds​
Parts Replacement:

Firing pin stop: when cracked

Slide stop: when broken

Extractor: when hook edges become worn or fails to maintain tension​


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## ttomp (Jan 28, 2008)

is it under warranty?


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