10.5 barrel is going to be very ammo sensitive.  Its due to the limited amount of the bore after the gas port for the ammo to charge the gas port before the bullet exits the muzzle.

So having said this, and the fact that the cycle is going to be so violent, when talking about extractors since the spent case still going to be under a great deal of residual bore pressure as the spent case is being pulled, we have to focus on only only the extractor, but the extractor spring as well.

Extractor/pin have to be heat hardened, then tempered correctly, or they are are going to be either too brittle or too soft instead. Hence too far to one side of the other, and either the extractor claw is going to shatter or just peen. And its the same regarding the pin as well.

Now regarding the extractor spring, The short bus version is to just make sure that you have a Colt M-4 extra tension extractor spring in play.  It will be the base middle ground for keeping the extractor claw from slipping off the case rim at the hard pull, while still allowing the extractor to open up during feedings to allow it to climb over the case rim just before lock up.  With a standard extractor spring, you can add a O ring to get it close to the same tension as the Colt M-4, while some of the other extra tension springs are stronger than the M-4 spring; which you can not add a O ring around them to increase the extractor spring tension instead (will be too much tension for the extractor to be able to climb over the rim at loading isntead).




So the break down with the chamber scrubbed correctly, the upper receiver bearing areas CLP lubed correctly (including the buffer tube parts as well), it to fire about a 100 rounds, the go police the brass.

On the brass, take a good look the rims of the spent cases and should be telling the story.  Rims bend inwards means too much extractor spring tension during loading, while rims bent backwards means the that the bolt is opening up to soon instead (too much gas pressure to the gas system, or the recoil spring/buffer too light instead).


On the extractor as you are cleaning the bolt, again the claw of the extractor should still be sharp (should be sharp for several thousand rounds). And regarding the extractor pin, just wear marks from the extractor pivoting on it.

Lastly, we need to come back to ammo sensitivity.  To short bus it here, find either factory or reload your ammo until you find something that will cycle it correctly as pointed out above.