Built first AR and got a problem

[G22]

I built my first AR and love it when it's working right. I bought the upper as a compleat assymbley. My question for you guys that know more about them than I do, (which is little but I'm learning), is that about every 15-35 rounds the ejecter is not ejecting the case. You can see were the ejecter is coming across the case but it is just "flatening" the rim I guess you could say. What can cause this and what should I have done. I know I will have to have someone else do it and hope they let me watch and learn some more but I was still wanting to know some of yalls opinions. I mean after all most of the best advise I have recieved about my pistols are from here. Thank Yall.

[EkuJustice]

Is it pulling off the case rim and leaving the case in the chamber? What length/gas system? If it is pulling off the rim, there is an Oring you can put under the extractor to increase pressure on the extractor. I run that on all mine especially my SBR. If it is a 16 inch carbine gas system the bolt could be coming back too hard and too fast that it pulls off the brass. If that is the case, the oring should fix it and is the cheapest.

Edited September 19, 2010 by EkuJustice

[jmurch]

What kind of ammo? What kind of upper?

[RiggerJJ]

are you talking about the ejector or the extractor? two different animals....

by reading your post I suspect (as Eku did) you are talkin about the extractor, and his suggestions my help...

jj

[jaredr]

Is it pulling off the case rim and leaving the case in the chamber? What length/gas system? If it is pulling off the rim, there is an Oring you can put under the extractor to increase pressure on the extractor. I run that on all mine especially my SBR. If it is a 16 inch carbine gas system the bolt could be coming back too hard and too fast that it pulls off the brass. If that is the case, the oring should fix it and is the cheapest.

OP - here is an example of the o-ring eku is referring to (specifically the black donut looking thing). not sure where you got your parts kit, but if you go this route and purchase this from BCM, I would swap out your existing extractor spring and use theirs so you are starting off with a known quantity. Also - murch question on ammo is very relevant. if this happens only with one particular brand of ammo (or your own reloads), but does not happen with (for example) winchester white box, then you may really just have an ammo issue (particularly relevant if the ammo giving you problems is remanufactured or reloads from friend).

[G22]

Thanks for the info. It is just a 16" carbine gas system. It mostly does this with winchester but it has also done it with a couple others. Had someone else say probly the head spacing? Wish I could get the picture of the case to upload on here so yall could have a visual. But Thank yall, and I will try the o-ring to see if it fixes it.

[jaredr]

Had someone else say probly the head spacing? Wish I could get the picture of the case to upload on here so yall could have a visual. But Thank yall, and I will try the o-ring to see if it fixes it.

my $.02 - doesn't sound like a headspace issue. if you had too little (i.e. chamber was cut too short), the round wound not chamber properly and the bold would fail to close. if you had too much headspace (i.e. chamber was cut too big), then you might see your brass stretch on firing (or possibly see a case head separation where the brass cartridges breaks in half and the extractor pulls out the back half, leaving the forward half stuck in the chamber).

[jmurch]

As asked earlier in this thread does the case remain in the chamber? Like the extractor tried to pull it out but instead pulled a chunk of brass off the rim?

An easy check is to take the upper off and the BCG out. Take the bolt out of the carrier. Take the firing pin, extractor assembly, extractor spring, ejector and ejector spring out of the bolt. Point the muzzel at the floor and drop a round in the chamber. Put the bolt on top of the chamber and turn it so the locking lugs lock. It should not be hard at all. Take the bolt out and turn it over and the round should fall out of the chamber with only maybe a tap or so if needed. Do this with 20 or so rounds.

If it is tight now it will be too tight after it's fired and the extractor will just rip a chunk of the rim off.

When you re-assemble the bolt put new extractor and ejector parts in, or at least give them a good inspection and cleaning.

[mpeltier]

Are you using a collapsible atock? If so what weight buffer are you using? A Heavy buffer will delay unlocking a tiny bit that will generally allow the cartridge time to shrink back down to size and extract easier. And dont forget to lube the gas rings/bolt.