I will never use wheel weights-period.Loaded w/ dirt ,zinc and associated pouring problems. I ladle pour the Do-it Ultra spinner bait mold w/ hard lead and do the following-
1- Keep your mold ,slightly opened on the top of your lead pot when not in use.
2- Pour the cavities 3 times w/out wire forms and hooks for the initial interior,mold heat-up
3-Keep the ladle submerged in the lead pot when not in use
4- I use woodworking vices mounted on the edge of my exhaust booth to hold the mold firmly in place and don't have to worry about overpours spilling onto a gloved hand.
5- Flux lead often to remove impurities
6-I use drop-out in the sprue canal but smoke the interior of the mold cavities w/ a candle flame.
7- The harder lead needs to reach a temperature of 900 + degrees to pour these .Use adequate exhaust to remove all vapors @ these temperatures.
Personally, I will never see the need for hard lead in any jigs I pour- especially all of my custom double barbed models down to 1/16 oz. That said, harder lead w/ antimony is a must(I.M.O. and experience) for buzzbaits and spinner baits.
I stated this before- monitor your lead temperature inside your pot w/ a digital pyrometer and note which molds pour best @ a specific temperature.You'll also know when the thermostat in your Lee pot needs replacement and those thermostats do go bad.
Edited for additional content