I do a lot of casting. I stick with the single barb myself. A wire weed guard will add a bit more in cost and is one more step in casting. For the cost of what a lead head that I pour costs I don't worry about popping a head off it need be. I will try to push it off with the rod tip but if it is out of reach POP! Also if you use different sizes on a regular basis you might think about buying production molds. That way you can pour 8 heads of the same size at one time. Heat your mold on the lead pot as the lead melts. A hot mold will work much better with a small cavity.