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12/27/2005 3:21:40 PM EDT
My PD just acquired 12 DPMS carbines. I experienced several failures to extract. The spent shell casing was stuck on the breachface. I removed the stuck shell casing by hand and chambered another round. The malfunction repeated  8 times.

I stripped the bolt and noticed that the extractor was frozen. The extractor spring has a blue polymer plug in it. I assume this is DPMS attempt to increase extractor tension. The plug was sticking out of the bottom of the spring. The spring appeared wider at its base and was stuckmin the bolt. I flipped the spring over and reassembled the bolt. I was able to fire a few mags without problems.

Has anyone else experienced this problem? Should I shitcan the little blue widgets and install regular extractor springs?
12/27/2005 3:23:58 PM EDT
[#1]
The blue insert is supposed to be there.  Sounds like the spring was in upside down as the large end 'snaps' into the 'hole' in the end of the extractor.  The insert should be captive.

If it is a carbine, I would run a carbine rated spring, always with a spring insert.  A D-Fender would not hurt either.
12/27/2005 3:50:28 PM EDT
[#2]
I know DPMS uses the inserts. Do any other manufacturers use them?
12/27/2005 4:07:11 PM EDT
[#3]
Most do, it is a dampener to prevent surging in the spring.
12/27/2005 4:14:15 PM EDT
[#4]
Thanks for the reply. My personal AR is a Rock River. It does not have the insert
12/27/2005 4:18:14 PM EDT
[#5]
It should.  Remember, when you pluck a spring, it will vibrate.  The insert is to dampen this.
12/27/2005 7:10:34 PM EDT
[#6]
what ammo?
12/28/2005 6:40:56 AM EDT
[#7]
Winchester frangible
12/28/2005 8:51:41 AM EDT
[#8]
I am an armorer in the Marine corps, and on the M16 series rifle colt puts the blue extractor buffer; However, on m4 carbines, they put a black extractor buffer, which is made of a denser material to compensate for bounce when the carbine is fired on full auto. I assume your carbines for the PD fire full auto.  If so, you definately need to get the stronger buffer. I would also suggest a wolf extra power extractor spring, and/or the d-fender d ring insert if you plan on running these in full auto. I have seen plenty of recons M4s have extraction problems. Also, it did sound like the spring was upside down from your description.
12/28/2005 11:39:41 AM EDT
[#9]
Our carbines are semi auto only. The other 11 run fine. I believe the problem with this rifle was the inverted extractor spring. It seems to run fine now
12/28/2005 12:13:25 PM EDT
[#10]

Quoted:
the M16 series rifle colt puts the blue extractor buffer; However, on m4 carbines, they put a black extractor buffer,



the spring with the black insert is spec'd for both rifle and carbine now
12/29/2005 4:21:36 PM EDT
[#11]
Heavy Metal--

You are correct. My RRA midlength has the black insert in the extractor spring.
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