S&W MIM Replacement Parts?


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HGM22
April 4, 2011, 02:07 AM
Might seem like a dumb question, but I was reading about S&W's use of MIM parts and how this is supposedly a negative. Is there anyone making "better" quality hammers, triggers, etc. for S&W guns? Is it even possible, or would they have to be fitted by a gunsmith (in which case that would still be possible)?

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PRM
April 4, 2011, 09:21 AM
I'm not a great fan of MIM parts. Had a bad run of luck with broken hammer blocks on my M60-9. From what I could find out on the internet ~ mine was not an isolated problem. The MIM hammer block is a small and fragile piece that easily breaks under stress. However, it is a part in theory should not have that issue. S&W has started back putting stamped steel ones in their guns. At least that's what they told me when they sent me a nice stamped one to replace the second one that snapped in my gun. Issue resolved.

As far as the other MIM parts ~ I have carried and shot my M60-9 since 1997. No issues with the hammer or trigger.

Guillermo
April 4, 2011, 10:08 AM
MIM is a cost saving method of production. Nobody claims that it is better.

MIM (metal injected molding) parts are expensive to make but they save money by requiring no secondary finishing. Most MIM parts are produced to be very hard so as to make for a slick surface. The problem is that they are that same hardness all the way through, thus making them brittle.

They COULD put a very hard MIM layer over a softer, more flexible metal (that metal could be of any method of production, forged, cast or MIM) but then the main advantage of the MIM process, using the part "as made" (no secondary finishing) would be lost, thus eliminating the economic advantage to the process.

In addition, the high level of hardness that the gun manufacturers like Smith require generally make them virtually impossible to polish. This is why many gunsmiths will not do action jobs on them. They are susceptible to "burnishing" so rubbing them against one another, in the case of handguns, by dry firing will help smooth an action.

MrBorland
April 4, 2011, 11:35 AM
Might seem like a dumb question, but I was reading about S&W's use of MIM parts and how this is supposedly a negative. Is there anyone making "better" quality hammers, triggers, etc. for S&W guns? Is it even possible, or would they have to be fitted by a gunsmith (in which case that would still be possible)?

Power Custom makes a forged S&W trigger replacement (http://www.brownells.com/.aspx/pid=32494/Product/S_W_REVOLVER_CUSTOM_TRIGGER_KIT). Randy Lee (https://apextactical.com/store/product-list.php?pg1-cid4.html) sells a re-engineered forged spurless hammer and firing pins. Also, S&W Performance Center guns use forged parts, and they may sell them. Or, if you have them do action an action job, they may be willing/able to install PC parts.

But, as to whether MIM parts in S&W revolvers are bad and replacing those parts is necessary, it's easy to get the impression from these on-line forums than this is so, but my own experience and research into the matter suggests it's not as cut and dried as the purists would have you believe. I tried to offer some balance below:

This is why many gunsmiths will not do action jobs on them.

Have you actually asked, or are you just assuming? I have. Several well-known and well-regarded ones, in fact, and not a single one had issues about working on MIM-equipped guns. I've had 2 competition guns tuned using MIM parts, and they've been flawless, despite their hard use.

Check out Grant Cunningham's take on MIM parts (http://www.grantcunningham.com/blog_files/2ca22a8b4cae7a2da440a1f09f72d8bf-86.html). It's a good read. Here's a relevant snippet:

"Is there something inherently wrong with MIM parts? No, but the story is a bit more complex than that....I'm not at all averse to the use of MIM parts, where appropriate. Note those last two words!"

in the case of handguns, by dry firing will help smooth an action.

Another internet myth I'd like to see go away. Dry firing is a great tool and it'll strengthen your trigger finger, it's no substitute for a bona fide action job if one is needed.

Guillermo
April 4, 2011, 11:47 AM
Mr Borland,

It is always nice when you chime in on a subject.

While I agree with you that dry firing is no substitute for a real action job, it can smooth out an action somewhat. This is ESPECIALLY so with the "burnishing" of MIM parts.

And BTW, it is try that many smiths will not do action jobs on MIM guns. The main reason is that their customers are often not pleased with the results...because MIM parts don't polish well.

The Grant Cunningham blog is a good one. If you read deep into it you will see that he mentions that MIM parts do not play well with others. Also that they don't hold chrome well like in the JM gun.

It is this "don't play well with others" that makes me leery of replacing the MIM part with forged.

Still, this indicates that the forged part is better. I think that we can all agree that MIM, while often works, is not as good as forged.

Be well amigo

HGM22
April 4, 2011, 11:01 PM
What parts are MIM on a S&W 442? If they don't play well with others can I just replace ALL the MIM parts? I'd like to have the piece of mind with a carry gun.

Guillermo
April 5, 2011, 10:38 AM
you could replace the internals of your 442

or buy one made earlier than about 1996

the thing about it is that your MIM gun is not much less likely to fail than a forged part gun. most MIM parts are okay. But the action is about at good as it is going to get.

So if you are happy with it, keep it as is

madcratebuilder
April 5, 2011, 10:52 AM
Have you actually asked, or are you just assuming? I have. Several well-known and well-regarded ones, in fact, and not a single one had issues about working on MIM-equipped guns. I've had 2 competition guns tuned using MIM parts, and they've been flawless, despite their hard use.

Check out Grant Cunningham's take on MIM parts. It's a good read. Here's a relevant snippet:

"Is there something inherently wrong with MIM parts? No, but the story is a bit more complex than that....I'm not at all averse to the use of MIM parts, where appropriate. Note those last two words!"

Quote:
in the case of handguns, by dry firing will help smooth an action.
Another internet myth I'd like to see go away. Dry firing is a great tool and it'll strengthen your trigger finger, it's no substitute for a bona fide action job if one is needed.

AMEN!

"Another internet myth" There are so many!

MIM parts require a different technique when doing a action job. Heffron Arms was a pioneer with MIM action jobs back in the 70's and 80's with their work on Dan Wesson revolvers.

Guillermo
April 5, 2011, 11:04 AM
you could replace the internals of your 442

or buy one made earlier than about 1996

the thing about it is that your MIM gun is not much less likely to fail than a forged part gun. most MIM parts are okay. But the action is about at good as it is going to get.

So if you are happy with it, keep it as is

MrBorland
April 5, 2011, 11:15 AM
What parts are MIM on a S&W 442? If they don't play well with others can I just replace ALL the MIM parts? I'd like to have the piece of mind with a carry gun.


AFAIK, MIM parts included the hammer, trigger, rebound slide and hammer block.

I'm not necessarily an MIM fanboy. I love the older pre-MIM, pre-lock guns for what they are and what they represent. But I'm as much interested in function as form, and haven't found the newer stuff to be problematic.

My advice is not to sweat it much unless you find a real reason to, so in that regard, I agree with Guillermo: "If you are happy with it, keep it as is".

I disagree with Guillermo, however, on the immutability of an MIM gun's action: The final quality of the action is the sum total of many contact points, with only subset being between MIM parts. The burrs and blemishes that cause much of the grittiness in an action are from machining of the frame, so MIM or not, cleaning these imperfections can really slick up an action. If you aren't happy with the quality of the action, then, get an action job by a good gunsmith. It's been my experience that MIM guns slick up just fine.

If, on the other hand, you're concerned about durability, know that competitive wheelgunners put many tens of thousands of rounds through their MIM-infested guns without issue, nor do they worry about any. That ought to tell you something.

From a durability standpoint, I'd be more concerned about the 442's aluminum frame and trigger/hammer bosses/studs than it's MIM parts, but even there, it's unlikely you'll shoot it enough for that to be an issue.

Remo223
April 5, 2011, 11:29 AM
MIM parts can't be much improved by a gunsmith. That's why they don't like to work on them. Bout all that's worthwhile is to change the springs, add an extended firing pin, and add sideplate shims.

I like to take out the trigger and replace it with forged.

The rebound slide appears to me to NOT be MIM on new S&W. Anyone know for certain if this is true?

Guillermo
April 5, 2011, 11:40 AM
Here is an interesting read by Grant on a gun with a mixture of MIM and forged parts

http://www.grantcunningham.com/blog_files/e8b998dd63b440b469dd8c5d4d262aed-150.html

Thaddeus Jones
April 5, 2011, 12:38 PM
I prefer forged parts. Not only because forged parts are 100% the strength of forged parts ;) , but they also look better.

If the new frame shapes to incorporate the IL weren't hideous enough, that trough running down the back of the trigger completes the cheap junk look, for me. TJ

Remo223
April 5, 2011, 01:30 PM
there's no new frame shapes. All new frames are entirely 100% backwards compatible with old parts...excluding the firing pin of course.

Thaddeus Jones
April 5, 2011, 02:34 PM
The frame lines, on either side of the hammer, from the top strap to the top of the grip frame, have indeed been reconfigured to incorporate that idiotic lock.

The redesign is the reason the ugly MIM hammers appear to be buried in the frame now. Although.....perhaps thats best as they are less visible that way.

It has destroyed the graceful lines of the S&W revolver. This has been talked about, here, many times.

DPris
April 5, 2011, 02:50 PM
Thad has it right.
I directly compared a newer MIM 64 with my older non-MIM, for one. A distinct difference in that arc.
Denis

Remo223
April 5, 2011, 02:53 PM
oh geez, you mean the curve is a little flatter? big deal. I never even noticed it.

But if what you are saying is true, then that means side plates should not be compatible with the older sideplates. I don't know that this is true.

DPris
April 5, 2011, 03:05 PM
Reno,
The arc is different, and higher.
I have not tried to interchange sideplates, just agreeing with Thad & disagreeing with you.

Have you compared an older non-MIM frame to a newer MIM frame yourself, side by side?
If you haven't, you might not want to dispute those who have.

Whether it's a "big deal" to you or not doesn't change the fact, and it does matter to others.
Denis

Remo223
April 5, 2011, 04:56 PM
The only smiths I have that are MIM/lawyer-lock iare N frames, and I have no non MIM N frames. So I am unable to compare. If I did have a forged N frame I would pull out the sideplates and compare. All other smiths are K frames and all of those are forged. K frames and N frames have slightly different frames where the hump goes against the crotch of your hand. I think that requires a different sideplate but I'm not sure. I will check when I get home.

9mmepiphany
April 5, 2011, 08:01 PM
When you check, you'll also find that the sideplates between your non-MIM guns will not interchange either...it is a fitted part to each specific frame.

Having said that, there is definitely a frame difference between the frames of pre- and post-MIM guns

MIM parts can't be much improved by a gunsmith
They can, the smith just has to know what they need to do

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