Help!! My A2 flash hider won't set properly....

[texasgrunt]

Not to completely hijack your thread, but how do you set a barrel in a vice as opposed to the upper? It makes sense why you would do this (to avoid warping the upper when torquing, I suppose), but I'm not clear on how to vise the barrell tight enough to torque without scarring the barrel.

I know, newbie shining through...