Just seems tighter then I've seen. Haven't taken a chamber brush to it yet. Just swabbed out the chamber. Is it something I should worry about? or as long as it goes into battery, shoot it and let it wear in? Or send it back?

be careful in mixing 5.56 and .223...make sure you are using the right guages

Hmmm. I've heard it doesn't matter. But in this case its a 556 nato gauge and 556-223 barrel.

GO means GO. As long as you're not forcing it shut.

Define "force"

 My other ARs if I held the gun vertically and dropped the BCG from open it would easily latch. This one not only wont but after pushing it closed you have to really yank it to open.

You're supposed to just kind of gently push until you get resistance. At least that's how I believe it is supposed to be done, and how I do it.