Thanks--been reading up on some s&w's and the topic of mim comes up a lot along with the locks. I know the propaganda says its the greatest thing since peanut butter--but the idea of it and how and what it consists of still makes me uncomfortable.
Of course i was also one of the last revolver hold-outs for duty carry and did my share of bad-mouthing the glock "plastic guns" back then as well! History has proven me wrong before.[B)]
deputy125, Here's the concept with MIM parts. Each part is molded to very exacting tolerances. This eliminates the need for hand fitting so parts are truly "drop in". The older S&W revolvers were made with forged and machined parts. It was impossible to maintain tight tolerances when machining these parts so they were all made slightly oversize. The persons that put guns together were called "fitters" because each part was literally hand fitted. When a revolver was ready to ship, it ended up almost like it was hand made with an exacting fit.
S&W has been on a quest for several years to reduce manufacturing costs. MIM parts are actually more expensive to make but because there is literally no hand fitting involved, the assemblers can crank out a revolver in record time. The cost of a revolver is 80% labor, 20% parts so as you can see, it makes a lot of $ence to use MIM parts. S&W has also found ways to cut corners in the manufacturing process by changing or eliminating the very things that made a S&W revolver a fine piece of equipment. Even before MIM parts came on the scene, S&W eliminated such features as internal hammer and trigger bosses, recessed cylinders, pinned barrels, internal gas ring, and many other quality features. Each change meant a part was not compatible with the previous model so an engineering change number was added to the model number. Example: a 686 started off as a no-dash. Each change increased the dash number from -1 to whatever the current dash number is (-10 or so). When the 686-4 was introduced, not only were there internal changes such as the goofy extractor, the nice wood grips were replaced with Hogue rubber grips. I don't know what S&W pays for grips but retail price on a set of 686 wood grips was $65 and the Hogue were $16. The 686-5 was the first gun to have MIM internal parts which included the hammer, trigger, cylinder latch, cylinder stop, and hand.
Basically, the best of the S&W revolvers were the no-dash or low dash numbers. Each engineering change brought the quality down so it wasn't just the MIM parts although MIM was a big step.
As for the MIM parts themselves, they are much more precision than machined parts. They can be made just as hard and have much smoother surfaces (more wear resistant). So I would say MIM parts are actually better than machined parts with one exception. You can "fine tune" a machined part for tight tolerance fit but with MIM parts, you can't file or grind them because the case hardened surface will be removed and expose a softer core. If you own almost any brand of 1911, you will have a MIM slide lock and thumb safety. Many other brands of guns also use MIM parts. In the right applications, there absolutely nothing wrong with MIM parts.
I would not own a S&W with MIM parts. Not because of the MIM parts themselves but the lack of workmanship and overall quality. I have a bunch of S&W revolvers and the "newest" one was made years before MIM.
That is pretty much my understanding about mim----kind of like over-baking a biscuit. The outside is tough as all get-out but once cracked or worn through it reveals a softer inside.
Understand that because of this getting a good action job may be tricky. Have not read of any big failures on s&w parts but would be interesting to see what shape these mim parts are say 20-30 years of service from a shooter and not a safe queen. Read that smith has been using them for 8 or 9 years now for a few parts and their usage is increasing to possibly other parts.
Read that several claim mim is in use by ruger but i have not seen any indications of it. Just another reason to stay with ruger or find and older smith.
Thanks for the insight.
Some people consider MIM and investment casting as the same thing. They obviously are not. But to these folks cast is cast is cast.
I know of one poster on The Firing Line who had his MIM trigger break. S&W replaced it and that was pretty much the end of the story. That was several years ago and I've not read any further comments about S&W MIM parts breaking.
Personally I will not own a new S&W. "I", that's I, Me, and Myself, consider them JUNQUE.
How others feel about them is their business and I respect their choices.
As for other guns with MIM parts such as the 1911s Iowegan mentioned, should I purchase such a gun the MIM parts will be replaced with machined parts post haste. I have read numerous posts of MIM slide locks breaking without warning. I don't trust them.
I bought the new S&"W 642...but the hole in the side really is bothersome. I intend to have the integral lock dremmeled off myself if I cannot get a gunsmith to do it. I read a comment on the S&W site (lots of disgruntled comments on the newer S&W revolvers) where somebody stated, "S&W went out of business in 2001. An Integral Lock Company bought them up and now sells locks with revolvers attached". Now...I am not going to bash any weapon company...especially an American one, but I honestly will not consider buying any more S&W revolvers. I like Ruger. I realize that all Rugers are "works in progress", but I am willing to spend the money to have a little trigger work and hand workmanship done.