I have good luck with 125, 130, and 150g bullets. Really likes the 130g hollow point for some reason. Using varget powder and CCI primers. The twist rate is 1 in 10 and works with heavy bullets and subsonic loads. 180 grain bullets at 950fps punch nice round holes at 100 yards out of my TC but tumble out of my Remington which is a 1 in 12 twist. I am sure the TC will stabilize heavy bullets at high velocity but I have not had a reason to shoot anything over 165g at high velocity. If you are ever interested in shooting heavy subsonic loads through a suppressor the TC barrel works very well.