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We had 7 of this companies guns at a Ken Campbell class (a SWAT team) Aside from the chamber being 223 (but marked 556) all of the extractors felt "worn"- almost like butter on the claw.
Coincidentally, they didn't work (4 coil springs and blue inserts) so we replaced the whole mess out of pocket.
Which is why you shouldn't use hobby guns for real use....
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I highly recommend the BCM extractor (which comes in the BCM bolt upgrade kit). I've never seen a nicer looking extractor, they seem to work well too. I have 8K trouble free rounds on one of them.
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Bumping this to new. Anyone with the CMMG extractor?
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I have an CMMG upper on one of mine.
Here are comparison pics
CMMG on top, COlt on bottom
http://i16.tinypic.com/4qgfl10.jpg
CMMG Extractor
http://i10.tinypic.com/52v7q8g.jpg
Colt Extractor
http://i11.tinypic.com/6c49fa1.jpg
CMMG on top , Colt on bottom
http://i16.tinypic.com/4pov3u1.jpg
Another view CMMG top/ COlt bottom
http://i12.tinypic.com/4zvh3qt.jpg
Both appear to have 4 turn springs. The extractors themselves seem to have small differences where the eye holes are.
Now MY question for the experts here, is it recommened to upgrade the BCG and extractor with one of the kits referenced in the discussions. With the Colt I have a FTE ~every mag~ or two. The FTE causes the under/over jam. I have to drop the mag and cycle the bolt to clear the good and spent round. Mags are USG surplus. Im on the fence on who to blame but regardless, I am getting the idea that the extractor enhancements ought to happen anyway.
Any thoughts you might have on this are greatly appreciated.
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That is a MIM part. It is produced in quantity by a certain large pistol manufacturer.
There are many misconceptions that surround the MIM process, primarily as the output from the process is frequently used for cost saving rather than to capitalise on the inherent advantages of processing metal by this route. Employed correctly the process can produce near net shape items that will exceed the performance of the equivalent castings but the costs also exceed those of casting (Noting the thread on MIM fire control parts). The use of MIM can help the designer in controlling the fatigue life of a part.
This said I would be cautious of an unknown MIM in an application such as the extractor in a rifle that is intended to work hard.The loading transition into and out of this part is rather too concentrated. The accepted route to manufacture this part is from barstock (I will furnish pics of the process stages ASAP) and this is what is found in current military production. Despite this a barstock part from a cheap AISI grade steel will nowhere match a good MIM part.
Bill Alexander