If I may, I'd like to jump in here and ask those bullseye target shooters, is your AR using a stock factory trigger, or customized?
My match rifle (older Bushmaster a4 A4 rifle) has had a few accuracy modifications:
White Oak match barrel 1:6.5 twist, Wylde chamber
FSB attached with locktite green sleeve and bearing retainer (Taper pins distort and stress the barrel)
Fulton Armory NM free float tube
RRA match trigger
Stop cut out of rear sight elevation post for added elevation adjustment
Front sight filed down to 0.050" width
0.050" rear target aperture
FWIW, the rifle shot <moa in stock form, but I wanted to get rid of POA shift from sling tension and add a barrel that allowed for use of heavier bullets for the best advantage at 600 yards.