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?

I know DPMS uses the inserts. Do any other manufacturers use them?

Thanks for the reply. My personal AR is a Rock River. It does not have the insert

Winchester frangible

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.

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

Heavy Metal--

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