Identifying MIM parts

[shamu415]

How can one tell the difference between MIM and cast or Forged parts on a 1911?

[Plisk]

Look for cast points.

Ever build from plastic model sets? You know how all the plastic pieces are on one big piece and when you separate them, they have points where the you get a sharp bur or a circle indent or similar. Seams are something to identify too. Not all MIM parts show these, but if they do it can be a definitive sign.

[Kruzr]

Steel parts made via the MIM process won't have any casting lines. They will have the mold popper marks. These are usually small circle indentations.

[keenkeen]

What make and model?

[littlejake]

MIM parts are generally used in the smaller parts such as the trigger group parts. My own preference are parts made from bar stock. Essentially machined from one piece of steel. This is expensive compared to MIM parts. MIM parts keep 1911's affordable. I did swap out a couple of MIM parts in my SA Loaded model for parts made from bar stock.

Casting may be used for larger parts like the frame. Forging is better than casting.

The 1911 produced in WWI and WWII had most parts made from steel billet -- the slide was machined and all the internal parts had to be hand fit because of manufacturing tolerances.

As a rule, to avoid MIM parts, you have to go high end in today's 1911's -- Wilson Combat et al.

[Bug Splat]

Hard to describe but MIM parts have a grain look and feel similar to particle board I guess. they just feel different. Having done some machining working with bar stock and other types of metal I can feel the difference in the texture and weight. There is no clear way to tell by using a magnet if thats what you are asking.

[shamu415]

Ive seen some pics if a MIM arts broken in half, it looks like a grainy apple. I just can't tell from the outside. But the descriptions you guys gave me seems to give a better illustration.
I do know there is a lot of talk about MIM parts being unreliable but that is another debate.

Thanks for the responses thus far!

[keenkeen]

A well made MIM part can easily outlast the gun it is part of. MIM parts are a victim of poor QC in the past by some makers and an overall lack of understanding by many.

I would look for a quality part from a quality maker first, and then worry about mfg processes second. IMO

But if you are really interested in telling MIM, from Cast, from Machined from Bar Stock, this is a good thread to take a look at.

http://forums.1911forum.com/showthread.php?t=315999

[compulsivegunbuyer]

All MIM parts have ejector pin marks from when the soft "green" part is pushed out of the mold before sintering. MIM is here to stay. Most new production handguns use MIM parts. My new Sig p226 is filled with them.

[Brian1979]

Shot my Springfield TRP about 40k rounds and broke 2 firing pin stops and 1 extractor. The extractor was MIM from what I recall. I used to be obsessed with CNC parts but this gun has changed my mind. I just bought the new Professional model and it has a few MIM parts but it has passed many tests and been proven to be reliable in real world use. I just dont think this is an issue any more when produced and fitted properly.

Glocks, sigs, and most production guns are all MIM and yet nobody talks about them until they are in a 1911. Even though all those guns are known for running for ever people still dont freak out about the MIM until its in a 1911 and I just dont understand it.

[shamu415]

Thanks for the pics of the MIM part. I think people put the 1911 on a higher pedestal and standard.

[zfields]

If you look at them wrong, they will immediately shatter into tiny shards of metal.


At least that's what the internet says .

[keenkeen]

Thanks for the pics of the MIM part. I think people put the 1911 on a higher pedestal and standard.

Not sure what you mean by this...

But MIM parts are used in lots of applications today...including engine variants used in the Tranche 1 Eurofighter jet. So a correctly made MIM part should be up to anything a 1911 application can throw at it.