I have a Preferred Barrel in 223 for an impact action. It's a 7.5 twist, 20 inch, threaded 5/8x24, spiral fluted with flutes cerakoted black. It has about 150 rds through it. It was super accurate with the load I was shooting. Same hole with 3-5 shot groups, and half MOA with 10 shot groups (I can provide load data). I converted my Impact to a 6xc hunting rifle so I never shot the 223. I'm not exactly sure of the contour, but it's not a super heavy contour. Probably something like a light plama. I can get dimensions and pictures if interested.
I'd sell it for $380 shipped. It was over $700 new. Unfortunately I already sold the bolt for it.
Let me know if you are interested.