You cannot, in any way, "crimp" or otherwise damage a barrel with a vise, and especially not with any aluminum or wooden vise blocks. Ain't gonna happen.
. So if a vise isn't going to hurt the barrel, your large-arsed channel lock pliers aren't going to either.
But... If you used a barrel vise, you'd have both hands free to mess with the muzzle device. For a flash hider or other muzzle device, clamp the barrel just behind the muzzle. Wrapping the barrel in inner tube isn't a bad idea for vise jaw grip, by the way.
For installing barrels, clam shells are a good
second choice. It's always better to keep the biggest part locked down. You will hear a lot of discussion about how "holding the barrel in a vise is going to put stress on the index pin" or "on the upper." Neither of these arguments works, as far as I can tell; once you get the barrel nut hand tight, and assuming you're using some sort of grease on the threads, the barrel and the upper are locked together, and do not move relative to each other.
Edited to fix stupid fat finger tricks.