If driving through CA, handguns MUST be unloaded AND in a locked container (case, backpack, bag, ect) in the trunk (if vehicle has one). Don't bring the >10rnd mags. Also, if you have a CCW, it isn't recognized here so you're not allowed to CC.
The reason I asked which weight heavy buffer you got is that it may be cheaper to convert it to AR-10 pattern and replace the receiver extension with an AR-10 one (or even a VLTOR A5 one since it's the same length) and get a AR-10 action spring. Those two parts will cost you ~$60, while a heavy buffer's heavy buffer will be $100 minimum. If the UTG buffer you got is H2 or H3, I'd definitely do the AR-10 pattern receiver extension route.
guruofhotrod got it right. Your buffer is too long. UTG doesn't make an LR308 pattern buffer (for use in AR-15 carbine receiver extensions). You need an LR308 pattern buffer for that tube. Did you get the standard H-weight AR-15 buffer or H2 or H3?
The N6 is on hiatus right now. It's an AR-10B pattern gun so the amount of other uppers are pretty limited (Armalite and Noveske). LaRue and LMT use SR-25 pattern uppers, which aren't the same as the AR-10B pattern. You can easily buy a precision rifle in a DPMS or SR-25 pattern. You can also build a DPMS or SR-25 pattern gun with a Noveske AR-10B pattern barrel and AR-10B pattern BCG if you're dead set on having Noveske. Careful, AR-10B uppers (classic AR-10 pattern) are NOT compatible with SR-25 pattern lowers. It may fit, but rounds won't feed.
You guys using the built in editor mode or the raw text mode? If not, give that a try. To switch modes hit the light switch icon (upper-left most button on forum editor's toolbar).
Because it's a known quality company. For instance, you know the total weight with MI's 10.5" rail is 7.7oz (including barrel nut and mounting hardware) while the Megafins 11" rail really weighs 9.5oz total (since they don't include the weight of the barrel nut and mounting hardware).
A lightweight FF tube is worth it over the MOE + FSB if weight is a primary concern. The less weight further away from you the better. I'd personally grab a MI SSK tube though.
Stoner's original design didn't have a FA either. Ever wonder why there's that indentation in the BCG just behind the forward gas holes on the carrier? So your finger can push the bolt into battery if you need to.
With this grip you bring your middle through pinky fingers in and rest the finger tips on the front of the grip and lightly place your palm against the side of the grip. The thumb maintains a straight profile over the hand (and doesn't wrap around). If you google "Todd Hodnett grip" you'll see what I'm talking about.