My experience with T/C was the same as longwinters, only with a .300 Win. Mag. barrel. My barrel did great when it was hot, but the first four or five rounds would be in a 6"-8" string.
I sent it back, and T/C replaced it with a new barrel. The turn around was about six weeks. The new barrel groups fine for two or three groups of three shots, and then it gets hot, and opens up to 2 or so MOA. I'm OK with that as I don't anticipate firing six or more rounds with a single shot .300 magnum under practical conditions anyway.
I've had mediocre ( 1.5-2.0 MOA) accuracy with a .280 Remington barrel, and have had very good accuracy ( 1 MOA) with a .338/06 barrel, both from T/C.