Failure to go completely into battery

[oyster]

Hi Everyone,
Hopefully the brains here can help me. I've got a AR15 Parts.com upper, 18" SS mid length gas system w/ a BCA BC and Sanders bolt, Superlative Arms AG, a JP silent capture buffer and H2 weight and I run a suppressor. This sits on a RRA lower.
After about 750-1000 rounds with no problems the following issue started to occur(I shoot factory ammo, Hornady and PPU) - I would fire a round and assume the next round was chambered, pull the trigger and "click". Then assume it didn't pick up a round so I pull the charging handle let go pull the trigger and no click. I then see the bolt only two thirds forward. Apparently after my first shot the bolt ejected the spent round, pushed the next round into the camber but the bolt itself didn't go all the way into battery, just enough to reset the trigger. So, when I pull the charging handle back and let go the bolt starts to push the next round out of the mag, the nose follows the feed lip and jams under the case still in the chamber. Shortly there after bad words are said since this is night and pigs/deer are probably running everywhere.
I've taken the whole BCG apart, cleaned, greased/oiled and reassembled. I bought a chamber honer and did that. Sometimes this helps for a few shots but then it's back to this. This week when it happened after I dropped the mag and did a few function test with the charging handle the bolt would slam to a stop before going into battery. From what I could tell it almost looked like the bolt was out of synch and not camming over to miss the lugs on the extension. Not sure if that's possible.
Thanks for any help.
Jay

[lazyengineer]

Picture? I'm not sure what 2/3 closed means, but if that means the BCG is only 2/3 the way forward in the ejection port, that sounds like a bullet nose hitting the breach face or something- which I haven't really seen before.

[oyster]

Picture? I'm not sure what 2/3 closed means, but if that means the BCG is only 2/3 the way forward in the ejection port, that sounds like a bullet nose hitting the breach face or something- which I haven't really seen before.

Yes, that's when it picks up another round and it try's to shove it under the round already in the chamber, that's the secondary problem. The primary problem is when the BCG pushes a round from the mag but the bolt stops right at the face of the locking lugs on the extension, so not quite into battery. I'm causing the secondary problem by trying get another round loaded.

[LRRPF52]

[LRRPF52]

[LRRPF52]

[montana]

This week when it happened after I dropped the mag and did a few function test with the charging handle the bolt would slam to a stop before going into battery. From what I could tell it almost looked like the bolt was out of synch and not camming over to miss the lugs on the extension. Not sure if that's possible.
Thanks for any help.
Jay

Sounds like your barrel may have clocked in the upper. Cycle the action slowly and see if the bolt lugs are hitting anywhere on the outer lugs of the barrel extension, you should be able to feel and hear if this is occurring..If you have a Mid West Ind URR Upper Receiver Rod, you can use it as a gauge to test for a clocked barrel. If this is the problem, then we can go from there..

[Klem]

Oyster,

My initial impression is that it needs a damn good clean and lube. I read you've done this, but I mean pulling it all apart - like the ejector plunger and extractor off. Checking to make sure the bolt can cam and firing pin protrudes properly. The inside of the extension and around the lugs are free of grit. Carbon is off all the hidden parts like the shoulder inside the mouth of the carrier.

If not this, sounds like there is either (1) less gas to cycle, or (2) more friction on the cycling system. Maybe the recoil buffer is not as free to move as before.

With the hammer compressed, pulling the bolt out of battery slightly and letting it back into battery without having to let it go should be smooth and without the need to pull it all the way back, or needing to use the bolt assist (without ammo involved). You can do this quickly back and forth a few times after cleaning, and before using.

[oyster]

Thanks for all the replies! Sorry for the late response, I've been dealing with some minor clean up/repair after Ian just blew through. I'll get back to everyone shortly (back to work now)
Jay

[oyster]

I don't recall ordering a specific spring for the SCS just the H2 buffer for an AR15, also this is on a A2 buttstock.

Not sure what barrel brand AR15.com uses and I haven't measured the gas port

I'm running a SilencerCo Harvester 30

Thanks
Jay

[oyster]

http://www.brushresearch.com/brush-types.php?c1=4 and followed the instructions for honing the chamber. Can't say it did anything for this issue since it keeps happening.

[oyster]

Temperatures were 80's at night (I'm shooting pigs/deer for farmers) but this has happened when its 40 too.
No O-ring on the extractor spring
JP SCS is GTG
Carrier key good, was loose when I first got it but retightened it and staked the screws. I also have a Lantac Enhanced BCG I was thinking about changing out to. Any thoughts?
Gas rings look good, splits not lined up
Some soot in the FCG but not terrible, trigger functions well. Yes it is a RRA 2- stage trigger.
E-lander mags, cleaned about 3 months ago.
Mag catch seems to be functioning properly
Gas tube flange is showing signs of wear so I'm ordering a new one today.
I have everything apart right now so I will test the BCG in the receiver and extension this evening.
Jay

[oyster]

Thanks Klem. I'll recheck all this this evening.
Jay

[chatterbox]

I had the same problem and found that it was two problems: 1. Broken extractor 2. Undergassed. New extractor, and a good cleaning, fixed the first and an adjustable gas block fixed the second.

[montana]

I had the same problem and found that it was two problems: 1. Broken extractor 2. Undergassed. New extractor, and a good cleaning, fixed the first and an adjustable gas block fixed the second.

Adjustable gas blocks do not increase barrel port pressure, they can only restrict it..