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  #1  
Old 06-16-2011, 01:39 PM
thefitter thefitter is offline
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Is it possible to get a good LONG LASTING trigger job with a MIM sear?




I have heard that a MIM sear can not maintain a good sharp edge necessary for a good trigger break. Thoughts and opinions?

Thanks
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  #2  
Old 06-16-2011, 02:17 PM
Dave Waits Dave Waits is offline
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I have a Rock GI with 6,000+ rounds on it. Still has a nice crisp 4lb,3 oz pull. Same with my Kimber. So far.
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  #3  
Old 06-16-2011, 02:49 PM
thefitter thefitter is offline
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Quote:
Originally Posted by Dave Waits View Post
I have a Rock GI with 6,000+ rounds on it. Still has a nice crisp 4lb,3 oz pull. Same with my Kimber. So far.
Is that a factory stock trigger or did you have it tuned? Thanks
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  #4  
Old 06-16-2011, 03:23 PM
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jedi573 jedi573 is offline
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Disclaimer: Not a 1911 gunsmith!

There are plenty of arguments of MIM versus tool steel. The consensus is generally that it's less of an argument when it comes to fire control/ignition parts. Most prefer tool steel for these.

Look at it this way: most of the higher-end 1911s have tool steel sears. You might hear arguments that an MIM one is just as good, but you'll never hear the argument that an MIM sear is better than a properly heat-treated and shaped tool steel sear.

The price difference is negligible if you're on the fence.

If the question is just a hypothetical "Can an MIM sear hold an 'edge' as well as a tool steel sear?' then I'm not entirely sure. I'm not willing to shoot ten cases on five different guns to get a good sample size to figure that out, though.

Andy
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  #5  
Old 06-16-2011, 04:53 PM
yocan yocan is offline
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IMO if your going to get a trigger job there is no logic to the gamble of using a MIM sear. IMO my RIA crumbled, I've heard of many others doing the same with a trigger job being done to it. I see no benefit to using MIM the parts not expensive enough to justify it.
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  #6  
Old 06-16-2011, 06:32 PM
JiminCA JiminCA is offline
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Good MIM is fine. I have an older Wilson CQB with MIM hammer and sear. Has about 25K rounds through it and still going strong.

OTOH I have tried to get a good trigger on a MIM springfield sear or two and that was a lost cause. Didn't get to find out if the job would last because I just couldn't get it right and finally got the sear too short to be usable and tossed it.
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  #7  
Old 06-16-2011, 06:49 PM
rex rex is offline
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I think the question comes down to the vendor that made it for the manufacturer.My conclusion is this about MIM : Do you want the floors in your house made out of plywood or particle board?The structure of those are comparable to barstock and MIM respectively.I personally like grain structure for strength.

Last edited by rex; 06-16-2011 at 06:51 PM. Reason: haha,the colon made a smiley icon
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  #8  
Old 06-16-2011, 07:36 PM
RonS RonS is offline
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If I understand the MIM process correctly I think you can expect a good trigger action to last with a MIM hammer/sear if it starts out good as manufactured. I would not expect a MIM part to tolerate anything more than light surface polishing, certainly not stoning heavy enough to square up a part or reduce engagement.

I would not worry much about MIM parts in guns designed after the great increase in labor costs, guns designed to be assembled rather than fitted by hand with lots of filing and stoning of parts.

It would be interesting to see test results on hardness of MIM parts where someone would take readings on the original surface, then start surface grinding the part down and taking readings as they got into the interior of the part. I would like to know if there really is a "Skin" on the parts or if they are consistant all the way through.
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  #9  
Old 06-16-2011, 07:55 PM
deatheater2 deatheater2 is offline
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Sure. You can even surface harden the sear and hammer hooks.
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  #10  
Old 06-16-2011, 08:59 PM
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A hardened tool steel sear will hold an edge better than a softer MIM sear. The issue is whether or not you will shoot enough rounds for that edge to wear.
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  #11  
Old 06-16-2011, 10:57 PM
schmeky schmeky is offline
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My 14 year old Kimber has the original high mileage MIM sear. I tuned it and the hammer 13 years ago. After thousands and thousands of rounds, it is still the best trigger of all my 1911's.

This MIM stuff is humorous to me. Transmission ring gears, engine oil pump gears, and rear-end differential ring and pinion gears are MIM in the vast majority of vehicles today. High HP Corvette's and just about every modern vehicle on the road today has powdered metal injection connecting rods.

I remember when leaded gas was being phased out, when carburetors were considered superior to fuel injection . . . .
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  #12  
Old 06-16-2011, 11:01 PM
Dave Waits Dave Waits is offline
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fitter, other than fitting the trigger,no. no work has been done on the fire-control parts although I did install a Wilson Combat 'Value-Line' Hammer. It was a drop-in fit. Of course, it's MIM too. Oh, all the fire-control parts in my Pro Carry II are original. It has a straight 4lb. pull, breaks like glass.
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Last edited by Dave Waits; 06-16-2011 at 11:04 PM.
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  #13  
Old 06-16-2011, 11:07 PM
Jim Watson Jim Watson is offline
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Quote:
Originally Posted by schmeky View Post
This MIM stuff is humorous to me. Transmission ring gears, engine oil pump gears, and rear-end differential ring and pinion gears are MIM in the vast majority of vehicles today. High HP Corvette's and just about every modern vehicle on the road today has powdered metal injection connecting rods. .
But were these parts directly copied from the previous forged and cast parts or were they redesigned to suit the MIM process?

I am sure you could build a gun optimized for MIM but trying to copy a milled part in MIM does not seem as dependable. Just cheaper.
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  #14  
Old 06-16-2011, 11:23 PM
thefitter thefitter is offline
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My first inclination for this pistol was to replace ALL MIM and CAST parts. This was mostly to remove or at least greatly reduce the possibility of failure.

Colt custom offers trigger jobs but they do not replace any parts. I'm fairly certain I would get a decent trigger job from them, I'm just not sure how long the edges would hold.

After this thread I'm going to invest the few bucks and replace the parts.
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  #15  
Old 06-16-2011, 11:35 PM
rex rex is offline
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Schmeky,Very true.The problem lies in the vendor.Those making the components you mentioned are doing much better quality control because all the parts they make are much higher production numbers with a greater loss for warrantee-10,000 broke rods or pinion gears is going to come back and bite them with the after affects of a car being labeled as a warranty queen compared to 10,000 sears in a gun that aren't up to par in an event.The industry says themselves that MIM can reach 97 or 98% strength comparably if the process is done correctly,but there's alot of variation in the manufacturers.$ talks .I'd hazzard a guess the MIM in guns can be at a higher level of quality,but then it costs the same as the part they're trying to cut cost on.MIM is roughly nothing more than new technology casting,the porosity is just on a smaller scale.People that want performance or top reliability chose either top quality of the process or real steel parts.An example could be the Ford 4.6L,redline is in the 6Ks but that engine will handle 10K,the problem lies in the reiprocating mass holding together and not snapping a rod because the block is strong enough to handle it.Just my obsevation of it all.Both have and will break and it will continue until the next major technilogical breakthrough happens.I just prefer plywood over particleboard.
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  #16  
Old 06-17-2011, 07:08 AM
cjd45acp cjd45acp is offline
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I generally change out the MIM sear for an EGW now. OTOH I had a friend bring by a couple of Kimbers that I had done trigger jobs on years before. Both were very high round count guns. He just wanted to see if they might need a tune up. The MIM sears and hammers looked just as good as the day I did the trigger job.
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  #17  
Old 06-17-2011, 01:11 PM
BruceM BruceM is offline
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"A hardened tool steel sear will hold an edge better than a softer MIM sear."

"I'd hazard a guess the MIM in guns can be at a higher level of quality,but then it costs the same as the part they're trying to cut cost on."

It's my understanding that MIM parts of high quality can be hardened to the same BHN as a forged steel sear and if my information is correct, that makes this argument kind of moot.

The advantage of MIM is that large numbers of very close tolerance parts can be manufactured economically and that greatly lessens the amount of hand fitting required to assemble guns of repeatably high quality. The savings is therefore in labor, not materials. As a matter of fact, Smith & Wesson claims that the cost of material to produce MIM parts is up to 12 times higher than for the forged counterpart.

As with all things, the devil is in the details. A component that is junk is junk whether it be forged steel or MIM. The material chosen for a particular application must be suitable for that application and with MIM parts, more thought must be given to the selection process other than cost and at least one popular 1911 manufacturer was the poster boy for bad MIM parts used in the wrong applications. Further, Smith & Wesson decided that they would substitute MIM hammers and triggers for their CCH forged steel counterparts on their top of the line revolvers. These parts were hideous in appearance as compared to their predecessors and this, along with the IL and it's idiot hole in the left side of the frame left a foul taste in the mouth of Smith & Wesson revolver shooters and collectors indeed!

Custom gun builders use forged parts mostly for two reasons:

1. They are familiar with them.

and more importantly:

2. That is what their customers want as is evidenced by this thread.

A couple of decades ago, this debate raged between S&W and Ruger buyers regarding forged vs investment cast receivers. 100 or so years ago there were those who insisted that the flush toilet would never work. Some still insist that we never walked on the moon. The list goes on.

The fact is that HIGH QUALITY MIM parts work just as well as their forged brethren in the correct application and that included sears, hammers, triggers, etc.. In some applications, especially where aesthetics matter, they can be hideous and there are those firearms applications where they are just not suitable, period.

Bruce

Last edited by BruceM; 06-17-2011 at 01:16 PM.
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  #18  
Old 06-17-2011, 01:37 PM
Magnumite Magnumite is offline
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As mentioned by one poster, he has a CQB with MIM internals as the Wilson guns were being produced in yhat era. Wilson himself stated those parts were up to the quality of his pistols. He stated the only reason he went back to tool steel internals is because the customers expected and demanded those in his guns. I think that makes a statement for MIM quality.

MIM threads are going the way of lube threads. LOL
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  #19  
Old 06-17-2011, 01:58 PM
Jim Watson Jim Watson is offline
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The advantage of MIM is that large numbers of very close tolerance parts can be manufactured economically and that greatly lessens the amount of hand fitting required to assemble guns of repeatably high quality. The savings is therefore in labor, not materials. As a matter of fact, Smith & Wesson claims that the cost of material to produce MIM parts is up to 12 times higher than for the forged counterpart.
True, the material cost is high, but there are no shavings. Ithaca used to advertise that the one pound receiver of a Model 37 was made from a seven pound forging. There is not much waste in the molding process.

The flip side to fast, net shape and finish molding is that the molds themselves are expensive. I suspect that one brand of gun had so many reports of faulty slide stops because they were reluctant to replace the mold until complaints reached a critical mass.
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