.308 Extractor/Ejector

DarrellA · Dec 5, 2016

My 1st home built .308, from a 80% lower with a complete upper assembly from Alpha Shooting Sports.

The problem is that when the bolt is back the fired brass doesn't want to release from the extractor. The bolt either hangs open, stove piping, or partially shuts trying force the empty brass back into battery behind the next round or jams it up into the top of the upper.

The BCG was greased appropriately and dipped in Mobil 1, it's plenty wet.

Any thoughts on how to proceed? I'm thinking that maybe the extractor spring is too strong. Does that make sense?

Sticky · Dec 5, 2016

Out of curiosity, how does it cycle if you just cycle it manually with the CH?

DarrellA · Dec 5, 2016

Sticky said:
Out of curiosity, how does it cycle if you just cycle it manually with the CH?

Same problem.

However, Alpha recommended removing the O-rings from the extractor spring. I did that and manually cycled 40 rounds through. About 9 out of 10 rounds extracted and ejected properly. I'll try to get to the range in the next few days for a live fire test.

Thanks!

Sticky · Dec 5, 2016

Good deal, let us know how it works out! :thumbsup:

clandestine · Dec 5, 2016

Sounds like excess extractor tension. It could also have a weak ejector spring, or an ejector bore that was drilled too deep reducing ejector tension.

DarrellA · Dec 8, 2016

Progress! Removing the 2 O-rings freed up the extractor so now extraction and ejection is working.

Next problem - the trigger didn't want to reset. I backed out the pistol grip screw a bit and it made a world of difference. But I still get an occasional incident where the disconnector doesn't want to let go of the hammer. I can flick the trigger forward and all is well.

But I'd like to get it right. Before I take a file to the disconnector should I consider this a "breaking-in" issue and run more rounds through? The disconnector and hammer are greased - maybe they need more?

All suggestions & observations are welcome!

Thanks

CSHS · Dec 15, 2016

I would check the depth of your fire control group pocket. If you're not a solid 1.25" (I think it's the same as an AR-15) you'll have problems. 1.25 plus a little is fine, but less than 1.25 won't work.

DarrellA · Jan 4, 2017

CSHS said:
I would check the depth of your fire control group pocket. If you're not a solid 1.25" (I think it's the same as an AR-15) you'll have problems. 1.25 plus a little is fine, but less than 1.25 won't work.

Thanks, but I don't think that was the issue. Maybe. Because I did notice a tiny ridge left between the trigger hole and the pistol grip screw hole. The Dremel took care of that in just a few seconds.

The trigger was part of a LPK, basically a real cheapie. A little attention with a fine file and some 2000 grit sandpaper on the disconnector and hammer engagement surfaces helped a lot. But still a problem.

Then I picked up & installed a no-name trigger from Midway on sale for $30 and she's now running great!

I have to say, I was amazed at how easy it is to put together an AR from an 80% lower. A Craftsman benchtop drill press and a Bosch router were all the cutting tools I needed. I can spin a wrench but I'm not even close to being a gunsmith nor machinist.

The upper assembly was purchased complete.

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