Rattrap do a pack of Space Cowboys in their Fantastic Worlds miniature line, the head on the cowboy is a dead ringer for Hex. You could do a minor conversion by just giving that mini a new gun, or do what I did remove the head & place it on a better old west body (I used an Artizan Civil War body myself).
No offense meant Matakishi, if your super picky about scale like I am that mini just looks very tall next to most Artizan & Foundry cowboys, scales up great with Black Scorpion though.