Kinda the opposite for me, I use a protektor rear bag and lead sled weight bags, along with lead shot bags, lead ingots, etc. quite often when doing guitar work. Protektor bag is great for supporting the neck while doing fret work, changing strings, general setup type stuff. The weighted bags are handy for glue-up "clamps", etc. I see no reason that the vice / clamp you're referring to wouldn't work just fine for some gunsmithing work.
