I have a .308, built on a Remington short action, with a 24" Shilen 1:12. The best powder I have used with the 150 and 155 grain bullets is RL12 - comfortably delivers 2950 to 2975 fps and shoots under 1/2". I would expect a 2" shorter barrel to produce maybe 60 fps or so less speed; but each barrel is its own little DNA molecule - 2800 is not all that bad, especially if the accuracy and consistency is good.