I lucked in to one of these:
I also work on modern guns where it is more necessary to have a good vice.
I also use a 4-jaw in the lathe while fitting a plug.
As mentioned it is very important to have good blocks. Metal V-blocks are great, I line them with business cards. . You can use fitted maple blocks and rosin (like for baseball players or violins). That is very effective too. For ML plugs with a tang a big cresent wrench will do. Just figure out where the force is going and orient the wrench so you do not mess up the top of the tang. For a patent breech you must have a wrench that fits the plug. This is particularity important when removing a tight patent breech, like a TC.
My eye tends to twitch when I hear advice that recommends a bench vice and leather. The chances of the barre twisting is pretty good. IF that happens damage will be done. Tread lightly.