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Discussion Starter · #1 ·
I don't want to start a "I hate MIM" versus "MIM is the greatest" kind of thread here. I'm curious about actual experiences with newer S&W handguns.

The NRA just posted a short description of MIM parts manufacture and how this technology (metal injection molding) is used in firearm action parts:

https://www.nrafamily.org/articles/2020/2/1/gun-manufacturing-secrets-of-mim/

The first comment from readers is critical of the use of this technology, and has the first credible criticism I've heard, namely that the parts wear differently than forged billet machined parts (developing chips and cracks) even though they have a similar failure rate to the older more expensive fabrication technologies.

The comments said that this contributes to inconsistent trigger pull over the lifetime of the gun, and timing problems.
[HR][/HR]I have some older S&W revolvers and Semi-auto pistols built after 1996 (when the reader's comment indicates S&W started using the technology). But probably have not used them enough to start wear issues appearing. My service revolver, surplus from a police agency, was made in 1999 with MIM parts, and is likely the most heavily used of my handguns. I have not experienced timing or parts failure issues with this handgun:



Has anyone encountered the cracking, action deterioration and timing problems that the comments described in S&W handguns made since 1996?
 
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I like to shoot a lot. I have old guns and new guns and don't notice any difference in performance between MIM guns and non MIM guns. I really think it's a non issue. Besides if it wasn't for changing/modernizing our old guns wouldn't be collectibles. They would just be old guns.
 

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I have one newer and several from around 1980s time frame; I cannot notice any difference. Remember the aircraft industry uses MIM parts in those airplanes we fly in.
 

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The problem with the comment in the article is the poster doesn't proclaim any specific expertise such as being a metelurgest nor does he post links to pictures of the chipping.

Sure .. It seems intuitive that a metal part machined from a block of metal would have a better grain structure but I would think that casting could make a part more consistent than machining so in theory 100 guns of a batch would feel the same in operation.

I actually don't sweat it. I don't think I will shoot any of my guns to failure. People thought flying machines were silly too and how many thought plastic would be used in handgun frames. Time moves on.
 

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If MIM parts failed at higher rate than forged there would be 1000 pictures of broken MIM parts posted all over the internet. Instead we have thousands of posts by people with no knowledge of the subject other than what they have read posted by other internet geniuses
 

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I am not even gonna read the link. Folks get a mind set and that's it, might as well discuss the IL.:eek:

And That's when the fight broke out!:D

I do not care if it is MIM or made by Guss the Gunsmith, if it works it works. As mention MIM is the way things are made today. Cars Planes etc etc etc.

9mm or 45 ACP, 40 SW????
 

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Functionally I see no difference, the older parts did have a nicer looking finish. I can't recall seeing any broken MIM parts & believe the new guns as rugged as the old. Doing an action job on a new gun is about the same as an older one. I learned gunsmithing, blacksmithing & machining from old timers & know for a fact hand forged tools are far superior to anything cast or MIM. For example I have a cold chisel made by Grandpa from iron ore he mined, smelted, hand forged & tempered that will cut store bought chisels in 2. It's on it's 3rd generation of hard use, in over 40 years I've worn off about 1/16"... @ this rate it's good for another couple thousand years. :eek: Now back to guns, MIM parts are interchangeable which means gunsmiths are no longer needed to make parts, armorers can do part swaps. Buy what you like, they're all good & will last for generations. Now the plastic injected things are just tools that don't rust & ok for knock around defense guns (unless they're Taurus, Glock, Mossberg or Hi-point... then they're just junk).
 

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On side note, Ruger went from investment casting some revolver parts, like the hammer & trigger to a MIM process for those parts. The Ruger people seem to think it was an improvement. The trigger edges aren't as sharp and the checkering in the hammer spur is different
 

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Only anecdotal, but in doing action tuning on my MIM revolvers as compared to my older forged part revolvers, the MIM parts require less attention because there are no machining marks to smooth out.

As for longevity, the 3rd Gen pistols have had MIM triggers and hammers longer than revolvers, and those have been holding up just fine.

Remember, before the plastic fantastic pistols took over the LE handgun arena, S&W 3rd Gen's with their MIM parts ruled the roost, I'm sure if an issue existed, we would have certainly heard about it.

People seek out and buy the LE trade in 3rd Gen's and have nothing but praise for them, despite the MIM parts.

I've often wondered why there is a relatively wide acceptance of MIM in S&W pistols, but when it comes to the revolvers... OMG!! They've got MIM!! Junk! Junk!
 

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From the fire arm stand point MIM parts work. However that being said, those of us who have done some gun-smith work will tell you that trying to smooth the action of a firearm with MIM parts is very difficult .

MIM parts have some polymer in them and trying to smooth and stone a part is hard to do as you don't know the hardness of the particular part. The old case hardened parts were pretty reliable from the stand point of consistency the new MIM parts no so much. that is why action jobs on guns with MIM parts is so difficult to preform. The other problem is tolerances with MIM parts . Some gun the fitting is just fine and others very sloppy. While i don't mind guns with MIM parts i would rather stay with older guns with the forged heat treatment that can be exactingly made to fit ..

Just my thoughts
 

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Discussion Starter · #14 ·
I've had the same impression as those posted here. I've got both in my S&W revolvers. The older ones can be refined to a point close to perfection. The newer ones work fine, and most of those I have were precision fitted by someone (probably after they left the factory).

The forged and MIM parts seem to perform the same, and I've not seen any deterioration in the MIM parts either.

The very best revolver actions I own are in a Pre Model-18 and Pre Model-19 I acquired recently. It's not that far away from the action in my first S&W revolver, a 586 Pinto I've had for years.

I'm glad we had this discussion. It's based on experience and will help people into the future.

Marc
 

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Only anecdotal, but in doing action tuning on my MIM revolvers as compared to my older forged part revolvers, the MIM parts require less attention because there are no machining marks to smooth out.

As for longevity, the 3rd Gen pistols have had MIM triggers and hammers longer than revolvers, and those have been holding up just fine.

Remember, before the plastic fantastic pistols took over the LE handgun arena, S&W 3rd Gen's with their MIM parts ruled the roost, I'm sure if an issue existed, we would have certainly heard about it.

People seek out and buy the LE trade in 3rd Gen's and have nothing but praise for them, despite the MIM parts.

I've often wondered why there is a relatively wide acceptance of MIM in S&W pistols, but when it comes to the revolvers... OMG!! They've got MIM!! Junk! Junk!
You beat me to it. ! So many people get out of control about MIM. Hell if they were not told it was MIM they wouldn't know the damn difference.
Most new guns today are polymer Plastic parts and MIM internals, like you say Glocks and others are so damn reliable.
 

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Nothing I've ever had with MIM parts has ever had a failure. Can't say the same for "old fashioned" parts like the hammer on my first 4506 which broke off one day. It was bought used, so I don't know what happened to it before I got it. I went online and bought a new MIM one and off it went. I sold that gun when I needed cash and the present owner hasn't had any problems with it. MIM isn't a "Nope" thing at all for me, but I admit, I do like the old flash chromed triggers and stuff's looks more than a black MIM part.
 

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I think the MIM is as good as the older machined parts. Biggest difference to me is the appearance and fit and finish. Older guns have the personal touch in that a true tradesman hand assembled the gun so everything fit. That man had pride in his skill and it showed. With MIM being cast to tighter tolerances our "skilled tradesman" has become an assembler and the lack of personal skill does show. Not in function but in overall appearance. The newer assembly line guns, more quality issues (I don't remember my Granddad having issues with any new gun he had bought back in the early 20s and 30s), like the pride is missing and it shows. That is the biggest difference I see.JMO
 

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I think the MIM is as good as the older machined parts. Biggest difference to me is the appearance and fit and finish. Older guns have the personal touch in that a true tradesman hand assembled the gun so everything fit. JMO
I agree but the bummer is .. Most people don't want to pay for the extra care and attention. When I was still doing leatherwork for profit I considered purchasing a sewing machine. To that point I did a hand wrought saddle stitch and without sounding to immodest .. I made one very pretty stitch.

So I asked on a couple of boards if anyone cared whether a leather item was sewn by machine or by hand and after some 40 or so responses .. I think 2 guys said they would pay more for something a craftsman had stitched by hand. Everyone else basically said .. If I can save $20 I dont care ... its just kit.

Cant compare the look or the durability of a hand stitch to a machine stitch but it was about $20.

I happen to be one of those freaky people who will happily pay extra knowing a craftsman paid extra special attention to my piece and whenever possible look for small shops but ..
 

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I agree but the bummer is .. Most people don't want to pay for the extra care and attention. When I was still doing leatherwork for profit I considered purchasing a sewing machine. To that point I did a hand wrought saddle stitch and without sounding to immodest .. I made one very pretty stitch.

So I asked on a couple of boards if anyone cared whether a leather item was sewn by machine or by hand and after some 40 or so responses .. I think 2 guys said they would pay more for something a craftsman had stitched by hand. Everyone else basically said .. If I can save $20 I dont care ... its just kit.

Cant compare the look or the durability of a hand stitch to a machine stitch but it was about $20.

I happen to be one of those freaky people who will happily pay extra knowing a craftsman paid extra special attention to my piece and whenever possible look for small shops but ..
Ban the sewing machines!

If you ever have surgery be sure the Dr Hand Stitches you. Non of that surgical glue (super glue) or staples!:D
 

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I would want to know which parts are MIM so I can make a choice on my purchase, or look for a better quality replacement part. I bought some Anderson lower parts kits for some AR builds. I didn't know the hammers were MIM. As they will now go into Bloomberg builds and I won't care. I have a feeling the most recent upper I bought could have a MIM extractor in the 5.56 bolt. It probably is.

I believe the MIM hammer in the M&P Sporter contributes to the smooth pull. Would I keep it as a SHTF fire control group? No. I have no idea of the failure rate on that part.
 
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