If I can offer some meaningless advice. Dont be overly concerned with buying nb bolts, noveske barrels, etc. Sure these items are good, but in my experience unless your going to put 40k rds thru a month. Stick with good quality parts, spikes, rra, etc,etc.
Rails are cheap and pricey. I've had both. My $130 utg has held up just as well as my $265 one.
Concentrate on decent parts and buy more ammo