I have thought of it, just haven't done it. I'm having a 8' workbench made at work and might do this but I'd really need two identical vises and mount the barrel holding one a little higher (use a piece of plywood) to elevate it slightly. Or make the barrel holding vise like a milling machine so that it could slide fore/aft to adjust to where it needs to be. It would be cool if a vise company made a vise like this for AR work.

