The past tense of cast is "cast." Especially in this particular usage refering to casting bullets from molds.
This has been pointed out before but disregarded. I can see all comments here being disregarded but can we at least give some measure of respect to the language?
"I cast some bullets today."
"I did some casting today."
"I casted Lindsy Lohan as a poet in my new film today." This particular useage is not widely accepted but is getting some maesure of traction in the language. That said, "casted" is NEVER an appropriate past tense for making bullets or sinkers....