First thing, define the true purpose of the rifle. Hunting? Plinking? Target? Varmits? This would dictate the calibrer, and barrel length, bullet weight and barrel twist.
I am in the process of building a Recce (wrecky)....for target shooting, Coyotes, possible three gun, and usage out to 700 yards using 75 grain Hornady HPBT @ 2600 FPS.
IMHO, there are too many "AR" builders out there to worry about getting a barrel specifically from an "AR" builder....most just source parts from "other places"
Get a good barrel from a "good" barrel maker...Lilja, Kreiger, Benchmark, Bartlein...etc...etc....this could cost $$$ But worth it.
Then look at Triggers. Timney, Chip McCormick, RRA, Geissele
Then look at Uppers...lots to choose from...IMHO, get a Monolithic one. That way, you have a LONG top rail that you can do anything with and you dont have to worry about briging the gap between the upper and handguard. The stiffer the upper assembly is, the better off you will be.
Would not worry about the brand or type of lower....it only exists to hold the trigger you got. Just don't get a Carbon Fibre or Plastic one....
I have a Adams Arms piston drive on a carbine. It is nice, but I am not completely sold on the Piston idea for an AR.
Do you want an optic, or open sights, or both...
Sights are a dime a dozen...
Optics...well, buy once cry once...don't skimp here!!!!
