I have shot several .5" groups with Winchester "white box" 55gr. FMJ's out of my 24" .223 barrel. I have had a couple smaller than that with the smallest at 3/16". If you look down the side of the barrel it looks like the finish is wet or something, there are ripples over a good portion of it? When I got it I immediately saw this and though, "Uh oh!" Shot it a few times and quickly fell in love with it. The yotes don't like it as much as I do though.