I just tested my xcr flashider. It prob took about 15-20lbs. to remove, but it came right off. Those lined vice jaws are the bombdigity, but today I just wrapped the bbl in an ole towel.
I bought a good vice from Northern Tool for about $40. This thing is reaaaly big, but it was only $40!!!
Vortex is the best flash hider (but it runs about $60). The Phantoms are a close second. But any of these are really only useful on short barrels, meaning 7" - 11.5". Most any FH works pretty well on barrels 16" and longer. I've got pics of a night-firing test I'll try to find.