Problems with new AR10 build cycling.. OPINIONS NEEDED!

[DirectDrive]

I found this spot rubbing on the BCG.. cant seem to find any other strong indicators other than that ejector is very, very stuff. Let me know what you all think as I let the BCG soak. Thanks!

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I wouldn't soak the entire BCG unless I was planning to disassemble after the soak.
I'd take it apart, clean and then reassemble.
You could also check the ejector and its bore completely while you had it apart.

 

[Jv22]

I'm interested in what you find is the problem as i am having the same with .223. I got an upper kit and took it out the range and it would only fire one or two rounds and do the same. After oiling the moving parts well it seemed to improve it with one exception, The first round doses not fire just like yours, just makes a mark in the primer and then to get the bolt open i have to pull on it while tapping on it with a hammer. After that all rounds work with no problem. It does this every time with the first round only. I use reloads and factory. All loads are with brass cases. usually lake city.

I will make sure to post it here when I do!

An update: I called BCA just to see if they as the manufacturer had any input. The immediately sent me a shipping label and said to send the BCG back for inspection / replacement. He asked for any photos I had and I gladly supplied them. I'll update again when I get a BCG back from them.

 

[Crazyeye24]

I believe BCA states not to use steel cased ammo in their uppers. Might want to try brass cased ammo.