Intermittent extraction problem

[crosseyedshooter]

I've always believed my rifle to be reliable, but today I was re-zeroing with Wolf Gold and got two failures to extract in 40 rounds. The rifle is a 16" Centurion mid-length with BRT 0.076" insert, A5H2 and mil-spec rifle spring. Both times, the empty case was only halfway out of the barrel extension and the fresh round jammed next to it.

What's troubles me is that the BCG is relatively new, with less than 300 rounds through it, and I put a BCM extractor spring with black insert in it not long ago. Is this early fatigue of the extractor spring or something else? I expected the BCG to go at least 5k rounds before spring replacement. Is that unrealistic?

Below are photos of three extractors, the middle one is the one giving me trouble. The left one is from a Sharps Relia-bolt and the right one is from a Colt LE6920, both with under 200 rounds.





If there's nothing obvious with the extractor or spring, all I can do is replace with another BCM extractor spring and black insert. Without identifying the cause of failure, it'll take some $$ of ammo to restore my confidence.

[MistWolf]

Repeat after me-
-Colt extractor spring
-Colt extractor spring
-Colt extractor spring

[georgeib]

When was the last time you cleaned the chamber? Had you been firing steel cased ammo in it recently?

[17K]

Repeat after me-
-Colt extractor spring
-Colt extractor spring
-Colt extractor spring

I came here to post this. It's true.

[crosseyedshooter]

Come on, guys. The BCM extractor spring is a known and proven quantity. I’ll have to take a closer look at the chamber but the rifle only has about 500 rounds since the last thorough cleaning. In hindsight, I should’ve saved my empty brass but I was in a hurry to get my zeros on two rifles during a lunch break.

This rifle hasn’t been thoroughly cleaned since we had our first born mid-last year. I run a bore snake through it after each range trip and lightly lube it before a session. I did shoot 40 rounds of steel cased ammo last month just for kicks, but the rifle is tuned to run on PMC Bronze at minimum.

Again, my concern is I didn’t expect the rifle to malfunction even if slightly dirty.

[MistWolf]

The problem you're describing is caused by a weak extractor spring or weak ejection. More often, the cause is a weak extractor spring.

If your chamber is dirty enough to cause the problems you're having, you have a weak extractor spring. I've seen people have problems with BCM extractor springs. Try one of your other bolts. If the other bolts are working well in their ARs, I bet they'll work well in your problem child.

[georgeib]

Yup. Definitely try a bolt that you know works well and see if that cures it.

[crosseyedshooter]

The problem you're describing is caused by a weak extractor spring or weak ejection. More often, the cause is a weak extractor spring.

If your chamber is dirty enough to cause the problems you're having, you have a weak extractor spring. I've seen people have problems with BCM extractor springs. Try one of your other bolts. If the other bolts are working well in their ARs, I bet they'll work well in your problem child.

Thanks for walking me through your logic. I see what you're saying and I think I'm just going to swap to a new extractor spring/insert without cleaning the chamber to see if the problem goes away. If it runs, then it was most likely an early extractor spring failure. If it still malfunctions then I will suspect the extractor and start working through that.

[17K]

Unless you're shooting laquered cases, the chamber should basically never need cleaning.

It's not uncommon to go 5-6K on a barrel cleaning with no problems. It'll also go 5-6K on a Colt extractor spring with no FTEx.

[georgeib]

Unless you're shooting laquered cases, the chamber should basically never need cleaning.

It's not uncommon to go 5-6K on a barrel cleaning with no problems. It'll also go 5-6K on a Colt extractor spring with no FTEx.

Lacquered cases have ZERO to do with anything. Steel cased ammo, whether lacquer or polymer coated, simply allows more carbon blow-by into the chamber during firing because it doesn't expand like brass cased stuff. So when you switch back to brass cased ammo, it can sometimes get stuck when it expands due to the carbon residue allowed into the chamber by the steel cased ammo. It's happened to me, and @MistWolf is correct in that a stronger spring usually corrects it. But so does a chamber cleaning.