I took the Norinco M1A out this week and althoughsome groups came in pretty tight, I had others that didn't even want to land on the paper.  Here is the rundown of "the facts" I found over the day:

1.  Tried Aussie .308 and South African .308, SA slightly better, but both having the similar problem.

2. castle nut had worked itself loose due to missing set screw.  Fron sight/FH still seemed tight. (getting replacement set screw this week- was missing when I got rifle and Brownells was out of stock)

3.  Gas plug came loose during firing.  Kept tightening up by hand, but like a dummy I left my M10 tool in my other stock (swapped stocks to synthetic that morning, had left tool in wood stock- plan to get another so each stock has one).

4.  Rear sight assmebly was tight, no probelms with looseness at all.

5.  Only got 3 hours of sleep night before.  Call me a dumbass for that.

6.  trying to shoot on a a black 6" bullseye target at 50 yards, had a tough time finding the front sight post when aiming at the taget (will switch to better targets next time)

7. Tried prone and kneeling position

I assume #2 and #3 (and #5) are the major causes of my problems?  

that loose FS and gas plug means stuff is rattling when you're firing.  Tightening them down TIGHT should help.  You might want to spend the $7 for a shim kit to shim your gas system and front band.