To be brutally honest, spend the $80 and get a real vise off of eBay with the aluminum sleeves. I have never had a barrel that it wouldn't hold. It gets frustrating when you buy one, saved $20... And have to buy another right behind it.
My neighbor and I just went through this with his vise. He had his friend machine it for him, but it won't hold a factory barrel tight enough to be removed like mine will.
what brand is yours? I've read in many places the Viper is good.