Mim Hammers & Sears

[XRe]

STI 1911 frames are cast, not machined.... FWIW...

[Irishlad]

As I understand it, frames for Colt, Kimber and S&W are forged...not cast.

Para uses cast frames.

No one would have a problem with MIM, if the parts didn't break.

In fact, if Kimber didn't "market" the process, MIM, I don't think most people would even know or care...unless they broke at a greater rate than other parts.

Kimber stopped using MIM for extractors(internal) and bbl bushings " I read", because they failed too often.

Now, I only see pictures on the internet of thumb safeties and mag catches snapped...that's an improvement.

[MoNsTeR]

Kimber frames are forged, and small parts are MIM. Kimber = Chip McCormick.

[TRUBL]

I am pretty sure the colts, kimber, para and S&W are cast.......may be wrong, but I have really good sources on this type info. Infact....I am 100% sure on Colts and Para's. BUT.....all frames can crack, can't they?

Irishlad, you are correct.....what is the frequency of breakage. That is what really counts here as all parts that move are prone to breakage. I know that having a part break gives the owner a 100% feeling of breakage....but it is the over all useage that counts.

I wish I could say all guns are 100% and never fail......but the reality is that 5% return rate is actually outstanding for any manufacturer......and 2% is almost unheard of, although there are a few that are even better than that......and using MIM parts too.

I've seen junk parts made from the MIM process.....way too soft or the otehr extreme, way too brittle. The selection of mat'ls and heat treating (ok....and a good MIM manufacturer) is paramount when designing these parts.

[Irishlad]

TRUBL:

I'll wager my own 1911 Colt (with a cracked frame I might add), that Colt uses only forged frames for their 1911's. I may try cast next time.

I've had great usage out of a MIM sear and disconnector, many rounds, but when I replace it soon, I'll go with the "barstock, etc" stuff since the retail cost difference is small for a couple of items.

If your producing 40,000 guns, the savings is significant with MIM...no doubt.

They just need to save a bit less and make sure they do it right.

We agree I believe.

[bountyhunter]

The thumb safety on my Kimber Custom II broke as I was cleaning the pistol after my first IPSC match.  At least it waited until I was done. :/

I believe the part is MIM - there is a faint "flash" line on the back, and the inside looks like powder....I'll attach a pic.

It's considerably irritating waiting for Kimber to send me a new part; I'd hoped to have it by now. In the meantime the gun is in pieces. <sigh>

<{POST_SNAPBACK}>

And that's the problem. MIM is a fine process, but not well suited for long thin parts. Why? Because MI is subject to specific flaws invisible to the outside:

1) Air defect (internal void)

2) Grain defect (metal powder not uniform, a big "chunk" was in the mix)

Either will produce a weak spot which will cause a catastrophic failure in a thin piece which is subject to stress.... like an extractor or slide stop or safety lever.

DUHHHH!

I think MIM is a feasible choice for thick parts like hammers and triggers, maybe sears.... problem is they are using it for everything except the recoil spring.

[TRUBL]

Funny thing here, after seeing the picture and all of the thumb safety & talking about MIM vs machined form billet.....I too had to replace a safety that failed.

It was an STI I have (the only one I have....as I shoot SVI).....the thumb safety failed. It got bent, and now falls out VERY easy. Whether it breaks or bends....who cares, it failed. I did replace with some safety I had laying around here from my 'box' of 1911 parts. I believe it is of all things.....a die cast part. True story, just replaced it a couple days ago.

Personally, I think the guy who owned the gun before me had no idea how to dissassemble/assemble his pistol and tried to force the safety in and bent it.....which is how most safety's end up failing anyway, trying to force it in, not knowing the gun has to be cocked.

Does this mean STI parts are junk?....nah. Infact I'll bet you if I sent the gun in, it would be replaced for free and with a part made the same way as the original. And that part would possibly the life of the gun. But, heck I have the stuff here and the know how.....so I saved a lot of time doing it myself with what I had. And, I suspect the part I put in will last the life of the gun as well.

Take care guys......I can't beat a dead horse anymore....we are all type 1 personallities and we have our opinions, we'll tell you what it is whether you want to hear it or not

[JeffCSR]

Kinda like the guy that would not buy a Japanesse car, but every appliance in his house is made over there.

LOL... that's me

Thanks for the input guys.

[Sam]

I had a McCormick MIM hammer break last year after about 6,000 rounds. The hammer started falling to half-cock. Examination revealed a crack originating around the hammer pin hole and running all the way out to the edge. Now, I'm no mettagur.....metalgis.....Oh hell, I can't even spell it.....I'm not a metal engineer, OK. But, I've been to 3 goat ropings and 2 county fairs and I ain't never had no tool steel hammer break in any way. I'm done putting discount parts in gunz-o-mine. Most 1911 buyers will never put 6,000 rounds through a pistol in their entire lifetime, so I can see why MIM parts are plenty good for Mr. Average gun owner. For guys like us, 6,000 rounds is just off-season practice. I personally don't care if someone else runs them or not. We all gotta do what we are comfortable with. And I'm not comfortable recommending MIM hammers and sears to any of my friends.

[EricW]

I've been to 3 goat ropings and 2 county fairs and I ain't never had no tool steel hammer break in any way.

<{POST_SNAPBACK}>

Sam,

That's about the funniest thing I've ever read on this forum. I'm laughing so hard, I can barly tpe..

[Run n Gun]

When I replaced my Kimber hammer and sear with EGW parts I decided to practice stoning and cutting the release angle on the Kimber part. It took about (IIRC) about 60 seconds to cut the Kimber part but it took 2 1/2-3 minutes to make the same cut using the same stone on the EGW!

Remember, MOST gun owners run a box or two a MONTH through guns and think they’re shooting a lot. I’m sure MIM has its place, but I’m also sure that “place” isn’t in MY gun!

Ed

[jjanglin]

Well guys if ya wont listen to the ole school smiths like Ross Carter then

you will continue to have problems.

The only reason I mentioned Cryo treating as an allternative is to point

out you can help inferior parts like the ones Para uses and mim parts

if you want to. Me I use nothing but parts that are proven to be top notch

like EGW or Nowlin and Ive seen them break now and then.

Anything mechanical is going to give up now and then no matter what

ya do or think ya should do!

Jim Anglin

Sailors Custom Pistols

[Ross Carter]

Ole School? Well yeh I guess I am. Ok question time. Why did the big manufactors start using mim? A. to save money B. to make a better pistol. The answer is A. We need Geo from EGW to chime in here, he knows about squirted parts.

[JeffCSR]

MIM certainly does have it's places, but hammer hooks are so small it raised my concern. The hooks on my Kimber's hammer rounded off prematurely and I replaced the part with a Chip McCormick just because. I thought it was okay that it was MIM, but that Kimber just didn't follow the recipe as good as Chip did. I've had several parts in that Kimber I replaced because they were "soft" but have had good luck with the replacement parts bought from Chip. (I know they're the same, I just thought they were made in different ovens by different chefs)

Beretta uses MIM trigger bars.... I gasped when I learned that and thought.. "No way!" but I pulled 2 off to compare, a newer 92FS Inox and an old 92F. It is obvious, the older part had machine marks out the "wazzoo" and the newer one had none... Apparently this part is a beeotch to machine so MIM was a necessary evil.

One day I hope to shoot more than I type, so I should save my pennies then and save up for the better parts.

[eerw]

The answer is A.   We need Geo from EGW to chime in here, he knows about squirted parts.

<{POST_SNAPBACK}>

Here is a thread from another forum..George has some cool photos of a MIM sear magnified showing some voids in the metal..anyway good reading...

MIM parts

I have talke a lot with George about MIM, stress areas/fractures, machining, etc and most of the time it goes over my little brain..but everytime it amazes me how much he has played, tested, broken, built things to see what works and doesn't. Good guy to listen too..

[JeffCSR]

Yes George is very cool! I always enjoy his experiments he shares.

[Sam]

Sam,

That's about the funniest thing I've ever read on this forum. I'm laughing so hard, I can barly tpe.. 

Dang, that was supposed to impress you. An incredible Fox Pass on my part....... I forgot that you have actually flown in an aero-plane!

(Durn city boys......done been everywhere and seen everthin' from Maine ta Spain......)

[Flexmoney]

TWO county fairs??

(Show off!!)

[EricW]

I've never been to Spain, but I kinda like the music...

They say the ladies are insane there.

[Carlos]

Boo Radly: a friend who used to help out at the shop had a Kimber MIM safety fail in EXACTLY the place shown in your photo. He did not shoot it much & he was not a competitive shooter (no dry fire, did not ride the safety, etc) It was simply a defective MIM part.

This brings up a thought:

1) Are there any air voids or un-fused granuals in a quality, name brand part made of cold rolled steel or forged steel or billet tool steel that has been EDM'd or traditionally machined?

A: unlikely

2) Are there any air voids or un-fused granuals in a MIM part?

A: Maybe.

For sears & hammers, I will personally stick to tool steel parts from EGW, STI or SV. I like my SV hammer so much that when it developed a hairline crack around 90,000 rounds, I had it welded for $20. Regards,

D.C. Johnson

[JD45]

I went searching for this old thread because I remembered posting about stock MIM Kimber parts. After my hammer fell to half-cock for the first time in near 15,000rds., I tore the gun apart to have a look.

The hammer hooks are still very sharp and look fine. On the sear, the edge between the primary angle and the relief angle doesn't seem sharp or well defined. So, I lightly stoned both angles, just enough to sharpen it. I also increased the tension on the sear spring. Now the trigger-job is almost a pound heavier( the extra pound feels like five after getting used to a sweet trigger). Shooting 50rds. didn't make the hammer fall, but who knows when it will again.

My new opinion is to buy a good tool steel hammer and sear so you won't have to worry.

[Heath]

The grain structure of steel is entirely dependent on the heat treatment and tempering process and can't be seen with the naked eye. Any time one can see "grain" in a steel part, that's likely the results of voids in the cast or molded part.

[EricW]

You can't make chicken salad out of chicken shit.

- Dennis Brown

[JeffCSR]

I noticed recently on one of my Springfields that the sear tip is ruined. I cleaned it up after a range trip and discovered the sear no longer had an actual primary angle.... It also had a very light pull, I guess I was working toward a hammer falling condition but caught it before anything happened.

I do at the very least trust Chip's mim sear more than a "Idon'tknowwhomadethispartforSpringfield" cheap soft mim sear.

I tryed to stone one of Chip's sears and it's hard as a brick.

[geo]

Lots of good info on this post guys.

Hi

My first discovery of mim was trying to anneal mag catches in 88 to make it easier to drill and tap. black good came out. the gun was a colt, the sear, disconector and mag catch were suddenly different. turns out it was mim.

the sears were pretty hard, Colt of course chose someone to do a good job but with shooters like Koenig and Piatt we could not get them the triggers they wanted on the sears. We sought out a Ser 70 machined colt sear. they were 52 53 rc and hard through. and they hold an edge. Colt did not ring the bell saying were going to this new process, not many new what was going on. Later we were offered sears from Isreal for under 2.00 each so I have a good idea why the parts started showing up. Later Colt used a Mim extractor but they failed often and they were dropped a couple years ago.

Kimber comes on the scene and Chip rings the bell MIM is Here Mim is here. The engineers at kimber are pretty smart fellas, good work, radiuses in corners etc. but Mim was not up to it. First the bottom of the bushings were breaking off, than the extractor hooks seporated, Novak told me he had some front sights break off stock Kimbers, (the other day we broke a sight off call it a test, and it was EASY)

Mag catches have a small section if you cut them away. they are breaking, as are safeties.

Yes you can inject tool steels but the strength does not approach bar stock.

I have some nice 500x photo's of mim and tool steel it is day and night, you could do a class, Mim for 6 year olds.

Cast frams are intersting Browning has had good luck with cast frames vs forgings, think of taking all that material, machining it and the residual stress left in there. I have photo's of Caspian frame parts and they look 200 % better than any mim photo's I have

part of the mim question is where is it made? India, Spain, Isreal? and how can you tell? and is it checked? We have checked sears from 2 manufactures of guns that are in the RC 20's how long will that trigger hold up?

Someone mentioned the contact area on a sear, yes it is really small. perhaps .002 x .092 on each side. Mim sears dent much more quickly than a tool steel sear. they will not hold a "trigger job" near as long as a tool steel hammer and sear.

Im with Ross, Koenig just won bianchi for the 9th time, and I asure you there is not a mim part in his gun if you shoot it, and I suspect if your here your a shooter, stay with the real deal, solid bar stock or forged steel.

Mim is a great choice for a grip safety so long as you can get it to blue and match the gun, same for main spring housings. Not the hammer, sear, fp stop extractor, slide stop, or mag catch though.

geo