SBR malfunction

[P2000]

Could the OP clarify the original post please, the beginning part mentioned failure to eject, but the last part said the case was ejected. I didn't see failure to extract anywhere.


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[Iraqgunz]

Well to start, a carbine buffer is way too light for a 10.5" barrel.

1. The buffer is unmarked
2. The bolt will lock open after last round
3. The gas key is mounted solid
4. Buffer spring is correct length

So......would I be better off buying a lower weight spring or buffer? Or a heavier weight spring??

[MistWolf]

Could the OP clarify the original post please, the beginning part mentioned failure to eject, but the last part said the case was ejected. I didn't see failure to extract anywhere.

In his first post, Tnemt stated his SBR was having a failure to eject and a failure to feed. When an AR has a failure to eject with a failure to feed and locks back on the last round (Post #14), the usual culprit is the extractor. The extractor loses control of the case before it can be ejected. The unejected case blocks the feeding of the next round.

If it was a weak ejector, the empty usually dribbles out or causes a stovepipe.

[P2000]

In his first post, Tnemt stated his SBR was having a failure to eject and a failure to feed. When an AR has a failure to eject with a failure to feed and locks back on the last round (Post #14), the usual culprit is the extractor. The extractor loses control of the case before it can be ejected. The unejected case blocks the feeding of the next round.

If it was a weak ejector, the empty usually dribbles out or causes a stovepipe.

In his first post he also says "To be more specific about the failure, it will fire and eject but then fail to strip the next cartridge out of the magazine. "
I'm not disagreeing with what you are saying can happen, however it may or may not apply in the OP's situation. The original post leaves some details up to the imagination. But one thing is clear, a car buffer has no place in a Windham 10.5 barrel gun.

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[Tnemt]

So for an update on my ongoing battle with my testy little rifle, I have replaced the standard buffer with a heavy weight h2 buffer. The rifle still does the same thing as before. Not sure what the deal is. Do I need a heavier spring? Do I need to order a light weight buffer/spring? I have a new big on its way for another rifle. I’ll drop it in and see how it goes.

[Iraqgunz]

When you conducted your lockback test, did you load one round in the magazine and then shoot it?

So for an update on my ongoing battle with my testy little rifle, I have replaced the standard buffer with a heavy weight h2 buffer. The rifle still does the same thing as before. Not sure what the deal is. Do I need a heavier spring? Do I need to order a light weight buffer/spring? I have a new big on its way for another rifle. I’ll drop it in and see how it goes.

[Ggro]

"To be more specific about the failure, it will fire and eject but then fail to strip the next cartridge out of the magazine."

Is the bolt overriding the next cartridge or partially stripping it?

What magazines? Have you tried other mags?

"It typically only happens when the gun gets hot or I fire at a faster rate."

Broken gas key screw?

[GrumpyM4]

Have you done anything suggested previously in this thread to ensure extractor and ejector are up to snuff?

I know it's not the vogue thing to do these days, but I'm going to ask which direction it's throwing spent brass when it does eject?

Clean it so it will run, and then run it and watch over time where the brass is going until it starts failing.

Even a minor indicator of bolt speed would be really helpful.