MIM parts.

[compulsivegunbuyer]

At one point isn't the forged/machine extractor MIM when it started life as bare bar stock. Isn't most machined metal at one point started its life out as MIM. Either it was MIM into bar stock, cylinders, I beam, h beam etc!!!! Than cut down and machined into whatever we want it to be! So is a bar stock was incorrectly forged than cut down and machined into 870 police/wingmaster steel extractor. You than have a defective extractor!

Bar stock is extruded under high pressure. Forgings are hammered into rough shape either hot or cold. MIM is a metal powder that is mixed with a binder to make it injectable into plastic style molding equipment. It is them "Sintered", which is heated close, but not quite to melting temp, which burns off the binder. The part shrinks evenly to shape and generally requires no further machining. MIM is not quite as dense as a piece extruded from molten steel. That really does not matter as long as it meets the performance standards of the application. I personally do not like it on hammers and triggers of S&W revolvers because it's ugly. Performance wise is just fine.

[nhattran_1528]

I don't think you understand the process of making a forging vs a casting.

Bar stock is extruded under high pressure. Forgings are hammered into rough shape either hot or cold. MIM is a metal powder that is mixed with a binder to make it injectable into plastic style molding equipment. It is them "Sintered", which is heated close, but not quite to melting temp, which burns off the binder. The part shrinks evenly to shape and generally requires no further machining. MIM is not quite as dense as a piece extruded from molten steel. That really does not matter as long as it meets the performance standards of the application. I personally do not like it on hammers and triggers of S&W revolvers because it's ugly. Performance wise is just fine.

Thanks for the info! I should Google more correct info next time!

[Steve_In_29]

That is not all the boards are full of. Meaning they are full of misinformation.

I challenge anyone to explain why two dentical parts designed to perform the exact same task, a task as simple as hooking on to the rim of shotgun shell and pulling backwards, are going to perform different because they are manufactured differently.

Explain how that is possible and be specific and I will keep an open mind and may be persuaded. Until then I maintain there is no difference in the performance on the two parts.

You are obviously entitled to your opinion but the fact remains, a dirty weapon was NOT the issue and once he installed the forged part his extraction issues disappeared. Which he tells me, quite a few other people have reported after doing the same swap.

Possibly there is just a tiny bit more flex in the (slightly less dense) MIM part vice the forged, allowing it to slip.

I work with electronics and it is not unheard of for an otherwise fully functional component/sub-assembly to NOT work when it is installed in the system. I have run into it myself.

[Bobby Ricigliano]

Is it fair to assume that my 1970's era police trade in Wingmasters are free of MIM parts?

[mjmagee67]

Here is a link to STI Guns take on MIM parts.

http://rabbit.30de.com/resources/faq/faq-mim/

Personally I shoot my guns until something breaks, then I fix it. I shoot USPSA and 3GN so I shoot a lot. I know some of the parts are MIM but no issues yet.

[aippi]

Here is a link to STI Guns take on MIM parts.

http://rabbit.30de.com/resources/faq/faq-mim/

Personally I shoot my guns until something breaks, then I fix it. I shoot USPSA and 3GN so I shoot a lot. I know some of the parts are MIM but no issues yet.

I click on the link you gave and read all of it. Sums up the issue perfectly. Thanks for posting that.

[aippi]

So is it kinda pointless to pony up the coin for the Police model as opposed to the Express?

No, not if you want a parkerized finish and they come with barrels and stocks not offered on the Express. All depends what you are wanting.

[riftol]

Possibly there is just a tiny bit more flex in the (slightly less dense) MIM part vice the forged, allowing it to slip.

As the extractor's claw slips over the shell's rim the extractor compresses a spring, right?

I doubt that as the extractor's claw slips over the shell's rim the force of the spring's compression is sufficient to cause the extractor to flex.

[Steve_In_29]

As the extractor's claw slips over the shell's rim the extractor compresses a spring, right?

I doubt that as the extractor's claw slips over the shell's rim the force of the spring's compression is sufficient to cause the extractor to flex.

As I said "possibly", since I have no way to measurably show why the part did what it did, I just know that it did do it.

[Garand1911]

When the MIM part breaks then go buy a newer better part.

[jeffrice6]

When the MIM part breaks then go buy a newer better part.

Well said! And this is true of all firearms.... So much drama related to MIM parts. Regardless of your lead delivery device, shoot it till you deem its reliable, then rinse & repeat. If something eventually fails, replace with stock or better!