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6/13/2016 8:37:47 PM EDT
Hey all, I'm having a very weird issue with my most recent build. Important information is it is a Radical upper and an AIM Surplus BCG. The gun ran fine for 100-150 rounds and from there on it has been partially locking into battery more times than not. Basically the bolt lugs are half covered when the BCG is as far forward as it goes with a round in chamber. My question is how does it go from smooth operation to locking up like that? I've cleaned it after every range trip so that, to me, means the headspace is wrong. How does a rifles headspace change? For the first 100 rounds it ran smooth and 100% reliable.
6/13/2016 9:35:39 PM EDT
[#1]
Is there something lodged in your gas key, perhaps?
6/13/2016 9:44:49 PM EDT
[#2]
Have you inspected the bolt? Does the ejector depress freely?
6/13/2016 9:50:19 PM EDT
[#3]
Sounds like something is stuck somewhere.  Gas key as someone else stated, something in the barrel extension maybe. Also pull your bcg and make sure it is operating freely by hand. May need some more lube in there.
6/13/2016 10:06:56 PM EDT
[#4]
Hey all, I worked with this for about 4 hours today with no success. BCG moves and locks freely without a round in the chamber. Chamber has been thoroughly scrubbed several times. Gas key is clear. Ejector depress into the bolt face. There is a large crack running around the inside of the barrel extension.... All indicators, to me, say my headspace has shortened up by something moving or expanding when it shouldn't..
6/14/2016 5:21:24 AM EDT
[#5]
Quote History
Quoted:
Hey all, I worked with this for about 4 hours today with no success. BCG moves and locks freely without a round in the chamber. Chamber has been thoroughly scrubbed several times. Gas key is clear. Ejector depress into the bolt face. There is a large crack running around the inside of the barrel extension.... All indicators, to me, say my headspace has shortened up by something moving or expanding when it shouldn't..
View Quote


Ew, that doesn't sound good. I'd love to see pics of you can get any.
6/14/2016 6:31:24 AM EDT
[#6]
Quote History
Quoted:


Ew, that doesn't sound good. I'd love to see pics of you can get any.
View Quote View All Quotes
View All Quotes
Quote History
Quoted:
Quoted:
Hey all, I worked with this for about 4 hours today with no success. BCG moves and locks freely without a round in the chamber. Chamber has been thoroughly scrubbed several times. Gas key is clear. Ejector depress into the bolt face. There is a large crack running around the inside of the barrel extension.... All indicators, to me, say my headspace has shortened up by something moving or expanding when it shouldn't..


Ew, that doesn't sound good. I'd love to see pics of you can get any.

6/14/2016 10:01:10 AM EDT
[#7]
Quote History
Quoted:
There is a large crack running around the inside of the barrel extension....
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That doesn't sound good.

EDIT: or look good.  Are you sure it's a crack?  You may what to pull the barrel and inspect it better.
6/14/2016 10:19:34 AM EDT
[#8]
I haven't been able to. I'm fairly confident in that being a crack because a minor stratch from debris shouldn't be un-interrupted around 75-80% of the extension. That's my thought at least.
6/14/2016 10:23:38 PM EDT
[#9]
Tried swapping out a buddies bcg to see if it'll run?
6/15/2016 11:47:39 AM EDT
[#10]
Am I the only one not seeing a crack?
6/15/2016 12:35:16 PM EDT
[#11]
Not sure i see the crack either though there is something that kinda looks like a crack bust still not sure.  I would swap BCG as well just to make sure the problem is not the BCG or a misaligned gas tube.  Wont hurt anything.
6/15/2016 4:08:24 PM EDT
[#12]
Couple of things to check:
Swap your upper on to your other lower.  This will rule out buffer/spring issue.
Swap your bolt.  Inspect the gas key, and make sure the bolt is lubed properly.
Check to make sure that your gas tube is still pinned properly, and that your barrel nut hasn't rotated causing the tube to bind and be off center in the upper.
Pull the barrel and and actually inspect for cracks/damage

Your head space should not have changed in that low of a round count.  I haven't had any issues out of any of my AIM bolts, but that it isn't to say that it hasn't developed a problem.  I haven't heard many good things about Radical barrels either - mostly tight chambers and bolt seating issues.

eta: Do you have headspace gauges?
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