I have just 1 assembled pistol upper from PSA, a 10.5". I haven't fired it much in the 3 years I've owned it, but it hasn't stumbled any with the 55gr. ball ammo I've fired through it.
I installed a little Romeo 5 red dot a couple of weeks ago and zeroed it at 60 yards from a rest. The last 3 shot group was zeroed just right and measured right about 1.5" horizontally and ¾" vertically.
