I have always spent a lot of time breaking in a new barrel because who can argue with the logic of it. I have a whole new respect for the process now! I was breaking in a Howa .223 Sporter this weekend which had just finished curing (three weeks) the duracoat camo job I had shot it with. I shot out the center target sighting in at 100 yards and and j&b paste every 3 or 4 rounds followed by a wash out with wd40 a swab out with tight patches with clp and dry patches. I'm up to about 40 rounds at this point. I shoot the number 1 corner target with a group of 5 that looked real tight except for my fouling round. I then really scrubbed the hell out of the barrel until I got no color with j&b, sweets and followup with the wd40 and clip. My third and fourth group were noticeably tighter which I thought was remarkable since I was only about half done. When I checked my targets I was amazed, the first forty shots were 90% perfect keyholes!! There was not a single keyhole in my third and fourth target. Each was around 3/4 inch groups. The only thing I could figure is something was left over in the rifling that was stopping/slowing down the bullet rotation. My grandpa would have said I knocked a dirt dobber nest out of it, but there sure was something in there. I think this rifle will be a real shooter after another round. Data: Hornady VMax 40 gr. 28.8 gr. Wc846 BC .200 SD .114 Probably somewhere north of 3400 FPS. Winds 10-15 gusty right to left crosswinds. 84 degree F 90% humidity.