When I shoot my Bushmaster M-4gery, I am shooting as if in combat situations very realistic range work. When I first got my Bushy I sighted it in using 25 meter Military method. It worked great but I never shoot my 14.5 in. barrel from a rest or the bench. I shoot from prone, kneeling, or in CQB stance.
This being said I shoot mostly from 10 yds out to 100 yds. Most shooting done is at 100 yds.
I get 5 inch groups, with Winchester .223 and SA 5.56 both 55 gr. With M-855 62 gr. I find more accuracy. Mind you I am using quick fire techniques, I train for a different ballgame though!