I use what lead i can get for my cannons(smooth bore) most of it is WW, and works fine, i buy the cast balls for my small arms(pistols/rifles). Just dont think it is worth casting ant thing under 1 inch.
Your comment got me to thinkin' and doin' some figurein',.........
100,.... .530 Hornady round balls from Track of The Wolf cost,.... $15.29
plus shipping and weigh 3.2 lbs.
I pay $1.50 per pound for 99.9% pure lead I get from a foundry,.... so, those same 100 .530 round balls, actually cost me $4.80 to cast (once I've bought a mold which can be used 1000's of times).