What's the story on MIM parts??


January 13, 2003, 11:49 AM
I keep on seeing where various 1911's internals and S&W hammers are made with MIM parts.

1. What exactly are MIM parts?

2. Is there any real reason to worry about problems if your gun has MIM parts?? Or is it more of a longing for the "good old days" of hand craftsmanship??

I mean are they perfectly functional and don't worry about it----Or is it you have big problems that need to be fixed-NOW! ??

3. If your gun has those parts--are there replacement parts out there that are better??

Or is this something like the whole thing about cast parts being inferior---that Ruger pretty much disproved---cheap and ugly---but they do work just fine.



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January 13, 2003, 12:28 PM
I'm by no means an expert on the process. I have not had any problems with the MIM parts in any of my guns. Perhaps its a bit of the old craftsmanship you mentioned, or perhaps others with more extreme requirements than mine are having problems. I think its more of the former than latter.

Some light and fluffy reading on the process is here (http://www.amt-mat.com/fr_mim_advantage.htm).

January 13, 2003, 12:46 PM
The main complaint with MIM (Metal Injection Molding) is that they can (and do) break suddenly without any give or warning.

Most people complain about MIM for the slide stop, thumb safety, extractor, and the hammer. Unfortunately, each of these critical components are commonly manufactured with the MIM process, and if any one of them breaks, your 1911 becomes an expensive club.

Putting all tool steel parts into a 1911 is almost guaranteed to put you over the $1000 mark in cost, with a few notable exceptions (like STI's Trojan 5.0, IIRC).

January 13, 2003, 03:10 PM
Here's a nice treatise that answers a LOT of questions:


Here's S&W's take on the issue, from a member of management:


IMO, there appears to be quite a quality difference between the process and/or vendor used by S&W, and that of so many of the 1911 manufacturer's. I've heard and read of many horror-stories regarding the parts in 1911s(only Kimber?). However, I've only read of one confirmed account with a S&W trigger breaking(at the top of the hook), and one other anecdote(by Tamara?) involving the same, IIRC.

January 13, 2003, 11:45 PM
To be fair, the best steel will be crap if it's not treated correctly. And that nice big bar stock didn't grow on a tree; it was cast itself at an earlier time. Not MI molded, but definitely cast. Things happen in the casting process too.

It's also safe to say that my "forged" barrel wasn't created by a blacksmith with a hammer and an anvil. Same with that $100 Henckels knife--check out what "drop forged" really means.

I'm off to smelt something.

Robert inOregon
January 13, 2003, 11:55 PM
It was my trigger that broke :( and since then S&W has redesigned that part.

If you are a recreational shooter, most likely you'll never tell the difference.

January 14, 2003, 12:03 AM
Everybody's got a story, and mine is that MIM parts are not welcome on any of my guns.

Kahr carrier
January 14, 2003, 12:22 AM
I dont like them, especially on a defense gun.:)

January 14, 2003, 02:46 AM
The only MIM part I am stuck with is the trigger on my 629...the rest..bye bye

January 14, 2003, 03:23 AM
Shmackey, If you like the Henckel knives go to K Mart and look at the knives there. Believe this, Martha Stewart has a line of knives that are identical to the Henckels except not German made. I have a kitchen full of Henckels and really like them but, I comared these to them and wow. Same exact dimemsions, handle, tang, solid one piece, etc. I have had them for a couple years now and they hold there edge and sharpen up just as nicely at 1/6th the price.

Shhhh, If you ever tell I recommeded a MS anything, I'll hunt you down! :D

Ps Sorry for post jacking

Lone Star
January 14, 2003, 08:03 AM
If you need kitchen knives, the most cost-effective are Victorinox, from the Swiss Army knife people. The nicest are the Wusthof-Trident.

Lone Star

January 14, 2003, 08:55 AM
Thanks for posting the treatise, Victor Louis. I would say there is nothing intrinsically wrong with MIM but it's all in the execution. If it's done right, it's good to go. All too often it seems like it's not. I would trust S&W to be one of the companies that would not use it if it was not up to their usual standards. The fact that they do it in-house means they control the quality unlike many users/assemblers who prolly buy from the cheapest supplier.

January 14, 2003, 12:28 PM
SW parts: FWIW: the MIM trigger and hammer on my 1999 model 66 looks beautiful and the ones on the model 66 I just bought have a very rough, bubbly appearance. The MIM hammer in my Para looks like something out of a toy gun made in Taiwan.

January 14, 2003, 12:32 PM
I would say there is nothing intrinsically wrong with MIM but it's all in the execution. If it's done right, it's good to go. All too often it seems like it's not. I would trust S&W to be one of the companies that would not use it if it was not up to their usual standards. You're right, BigG. But quality MIM parts aren't things you can make as a side line. If you can't afford to test hundreds or thousands of parts to destruction, the confidence level in MIM parts should be low because there are so many more variables involved over machining parts from stock.

Restaurants are a good example. You order a particular menu item, and it's great! Go back, order it again, and it's so-so. Same chef, same everything else, but the dish is just not quite the same. Chefs don't measure everything precisely, hence the variations.

Mass prepared food makers, OTOH, are able to get consistency because of the huge quantites they prepare. One can of Campbell's soup may come from a zillion gallon cooker where the ingredients only vary by a molecule or two from can to can over the years.

With smaller food makers, you can notice differences from one batch to another because they deal with smaller batches.

The BIG problem with MIM is that destructive testing is about the only way to validate the CURRENT process, and no manufacturer is going to destroy 500 units out of a 1,000 unit production run. They'll random sample test a percentage.

If critical MIM gun parts from a batch were tested properly, the good ones would cost more than their machined stock counterparts. I wouldn't trust ANY gun maker to properly test critical MIM gun parts because their volumes are just too low.

January 14, 2003, 01:21 PM
Good point, Blackhawk.

Jim Keenan, IIRC, mentioned that the US tried casting frames/receivers for some guns during WWII with good results.

Robert inOregon
January 14, 2003, 02:44 PM
My primary complaint about MIM is that you can't put a stop on the trigger and ALL S&W triggers, whether forged or MIM, feel like poop without the stop. When they reengineered the triggers last year, it would have cost "zero" to add a dimple for a trigger stop.

January 14, 2003, 03:36 PM
The ONLY part I've ever had break on any pistol was an original slide stop on a Remington UMC 1911 built in 1917. And that stop broke while I was shooting it with a .22 conversion unit!

I have two Kimbers through which I've shot tens of thousands of rounds and no part (MIM or not) has ever failed... unless you count springs which have worn out and been replaced. The MIM parts are still holding up.

I'm not going to worry about it.


January 14, 2003, 10:09 PM
Shmackey, If you like the Henckel knives

Bah. Hate 'em. I'll spend $100 on a folder but not on a kitchen knife--and I'm a serious cook. Lone Star has it right: the Victorinox/Forschner knives with Fibrox/Microban handles are my favorite. What they use in real kitchens. Dishwasher safe, about $25 for a chef's knife, and I am absolutely convinced that they take a better edge than Henckels or Chef's Choice. No, they don't hold the edge as long, but they're also a hell of a lot easier to get back in shape.

Wait...I think I continued the postjacking. Well, take it in context: sometimes the fanciest steel is wrong for the job.

4v50 Gary
January 17, 2003, 01:02 PM
What's the difference between sintered metals and MIM or are they just the same? I know Colt used sintered metal to make the internals of the early Mark III troopers. Wasn't too successful either and the sintered metal parts fell apart just like poorly made MIM.

January 17, 2003, 01:25 PM
I tend to use both the terms pejoratively but I would think MIM in its true form would have more temperature so the little grains or dust fuse to a solid whereas sintered just looks like it's compressed into a semi-solid sans heat or with lesser heat. The earliest use I heard of the sintering process was in WWII 9mm German bullets made of sintered iron, presumably in steel jackets. MIM is just a variation on the theme with a new neato sounding name, to me.

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