I have been lucky enough to be able to shoot Ace Barrels for the past 9 years.  The quality and accuracy of their barrels is absolutely top shelf.  I have one of their barrels on my 308 F-Class rifle, my 260 PRS/NRL gun (3rd barrel on this one) and also have a Vudoo 22LR with an Ace Barrel.  All three guns shoot extremely accurate.  All three barrels required basically no break-in and are very easy to clean.