For my coolant I’m using water soluble cutting oil.
I might fine one shot in a hand full that’s like the hollow sphere.
I’m just wondering if I’m at the point of getting the lead to hot, or if its the mixture of lead I’m using.
tatersalad ... I use water soluble oil and water in a three to two ratio and use a paint type mixer in a drill to mix the solution before adding it to the cooling tank.. I keep the coolant stored in plastic buckets between shot making sessions It sounds like there may be a pocket of coolant with not enough oil since the hollow shot are random.. Just a guess....