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Discussion Starter · #1 ·
I got a new 1991 custom(the one with videcki trigger) and when i took it apart i noticed the sear is cracked right where the the line of the mold is.
has anyone else experienced this?
 

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I have not heard of this happening, but in light of the amount of MIM stuff being used today its not that surprising that Colt has began using some MIM parts. I have heard that they are using some MIM parts in non stress parts. The sear would/could be one of the those parts. Given Colts service history of late, I'm betting they will take care of you at no cost.
 

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Yes I agree they will take care of you.
They quietly used mim.
disconector, mag catch (ever drill one of those buggers, they can be hard), sear (hi stress part)
from the early 80's.
I have seen the sears fail but rarely.
This sould speak to the quality of the mim parts that can be manufactured.
geo ><>
 

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I am realatively new to the forum, and at the risk of exposing myself,
what does MIM, EDM, CNC and anything else I may have missed refer to. I know it is a manufacturing method, but, I do not know exactly what the terms mean nor the pros and cons of each. Thanks in advance

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Originally posted by Shay:
I got a new 1991 custom(the one with videcki trigger) and when i took it apart i noticed the sear is cracked right where the the line of the mold is.
has anyone else experienced this?
Are you sure you don't mean the disconnector? The right tab side?
 

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Discussion Starter · #6 ·
It is the sear that is cracked. I ordered a set of sear,disconnector and hammer from Ed Brown. no more MIM parts for me, I already had problems with my Kimber.
 

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Kevin,

MIM is short for "Metal Injection Molding" It is similar to a cast part, except that a cast part is simply poured into a mold like a lead bullet, where a MIM part is actually injected, providing more pressure and higher density. (At least this is what I've heard) MIM and Casting are both inferior to Forging as far as density and strength go.

EDM??? I don't know that one.

CNC means I think "Computer Numeric Control" and is a type of machining whereby detailed machining can be performed using a computer to control the cutting. It makes for much tighter tolerances without hand fitting. (Most would agree, however, that hand fitting is still better.)

Well, that's what I know, and I am not a metal or machining expert, so feel free to correct me if I'm wrong.
 

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I avoid MIM parts, but they seem to be appearing all over the place because they are cheaper to manufacture. Even Wilson's has some MIM parts it sells for less than its machined parts. The slide stop on my Kimber is an MIM part and it broke right at the joint between the shaft and the paddle after only 500 rounds.
 

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Yes
MIM is Metal injection molding. they make the part using a process similar to injection molding. BUT they have to make the part larger than the finished part. The metal part is molded and they have to heat it to cook out the material that makes it moldable the binder I believe. the shrink is more than 10% so it moves quite a bit. problem is How much binder how dense the part is how hard and how much it moves around when baked. I have a sear here that is very crookid.
Yes Mach. from bar stock or forgings will be harder denser material and a better part. I was offered sears from a MIM co. overseas at 2.20 each so you can see why they have become popular. Kimber bought a mim co out of fl to make some of there stuff. Start up molds for mim were around 20k but have dropped to half that so they will be more prevelent.
The second part is very inexpensive. Baretta for instance does a MIM trigger bar, complicated part expensive to machine, and hard to cast well, With MIM they can make a part that needs little or no mach.

EDM wire. Electro Discharge mach.
By sparking thousands of times a min. a thin wire .010 ish is moved around a part and slices through the steel block to cut out the shape deisered. it can be very accurate .0002
it has a problem also, there is a micro crack from the heat, you turn the steel to incondecent level and the deionized water cools it, A sphire (of steel) created and floats it away.
somewhere around 6000 degrees. The sights that are from Thai. are a good example they were plauged with cracking.

EDM ram.
same electro process. But you make an electorode out of graphite. what ever shape you make you can burn into solid steel.
the edm does not know how hard the steel is so it can do heat treated steel and carbide.
same for wire. A comp electrod for example can be round on the bottom with radiuses on the sides and angel built in the front. We have offered EDM comps for 10 years.

For a gun that matters for Competiton or Carry I would pass on the MIM hammer sear Bushing slide stop. These are clearly hi stress areas. Springfields and chips beavertail great. thumb safety maybe. mag catch sure.
geo ><>
 
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