The barrels are great mate. The locking system for the inserts is really good, no movement on them at all. The barrels also very quiet and accurate. I agree with Micah though, when you use it it does seem to tighten up, and often is a bit difficult to unscrew, I have found using the rubberised part of the bottom of a mouse mat works a treat though.
So in conclusion no complaints from me, highest of praise for it
Ended up purchasing it from Pheonix, a 14" with 3 inserts and a barrel bag for it all for just £135, which in my opinion is a bargain.
Hope that helps.
Dave