I have a Remington 700 factory chambered in 8x57 (one of the "classic" chamberings) as well as my only TC Icon which is chambered in 308Win. Both of these barrels foul like pigs. If I put a nylon bore brush through the Icon, you can actually hear the sound made by the "gramophone finish" in the bore. If I fire 10 rounds through the Icon and examine the muzzle one cannot fail to recognize the 100% copper color on top of each of the lands in the bore. The Remington was not quite so bad, but it is really a 2MOA rifle at 100 yards, even with handloads.
I just wasted 4 months on a custom 8x57 barrel with Mc Gowan (which they had the blank in stock) after they said they could get it chambered and profiled in 4 weeks and after 4 months still no sign. So for the moment I am going with a Criterion in 308 and will get a custom 8x57 on order and wont have my rifle sitting somewhere untouched for 4 months... Criterion is offering barrels for the Remington held on with a Savage style barrel nut and I have everything I need to fit those.
How to deal with the Icon seems a bit more complicated, it was a very short lived rifle and Smith and Wesson has pulled the plug on customer support unless you have one which is still under warranty. No-one seems to making barrels for these, so I am probably going to have to remove the sporter barrel and reverse engineer the breech dimensions to see what I can get to fit. One of the big mysteries is what the bolt lugs engage in, since the bolt body is a bigger diameter than the bolt head. Hopefully the lugs do not engage in the breech AR-15 style... Its really a shame since I really like my Icon action. It is made well and the integral scope mounting point are great. Just the flimsy plastic magazine that is a turn off, but thats not just limited to the Icon.