Comes down to how much you are going to shoot it in a sitting. The smaller the barrel the quicker it heats up and starts throwing bullets. I recomend that you use a heavier contour like a straight taper to 1" at the muzzle. A heavy sendaro with a .9 muzzle will work well for you also. Just note that the heavier the barrel the more consistent it will shoot and more shoots before it gets too hot.
okay, thanks alot. I have bought a mcmillian htg LA stock for $250 that has a channel cut for a #5, is why I'm asking. I guess I could build something else to fit it.
If you have the option of picking a barrel, check out Broughton's 7.4 contour on their website. American Precision(Patriot Arms) just ordered one for my TRG-42. Should do well with that caliber.