I have a steel frame with a gap of .006 and a brass frame with a gap of .008. .008 is probably a little loose.
I think if you are careful not to torque the vice down beyond just enough to hold the barrel from turning, you won't have a problem.
I would say that if you damage the barrel it would manifest itself in the way the pistol shoots before you could measure it mechanically. It is much harder to get the barrel out than it is to turn one in. If the vice and liners apply equal pressure all along the surface, you don't need to tighten it all that much when you are installing the new barrel.
My reading of history convinces me that most bad government results from too much government. Thomas Jefferson