I started using a harder lead years back which helps. Done with 100% lead which is soft especially from eBay. I buy my lead from rotometal and get the 95% lead 5% antimony. It’s a harder lead. I never flux my lead either since getting this type of lead. Using a 20 lb pot and keep it full. Also I put the spout of the pot into the gate of each cavity when pouring. Doesn’t hurt to get a little powder paint on the bottom of the head where the wire keeper goes into it.