I have a youth .223 which has the same barrel, 20" in length and a lot smaller than standard contour. My first bit of advice is to keep it cool. Allow several minutes between shots. When I first bought this for my daughter, it wouldn't shoot any better than 4" groups. I found the barrel lug screw way too tight. I took the screw out and re-installed just snug. This brought the groups in to about 2" or so. I then followed the accurizing tips in the faq's and polished the bore with flitz. After about 80 rds thru, it will shoot 3/4" groups at 75 yds., as long as you don't let the barrel get ANY heat in it.