I cast from a Lee DC mold. The ball measures a consistent .600"; and the weight - I've only weighed them once or twice in the past - is somewhere between 325 and 330 grains; I call it 330. WW ball casts about .606" and weighs closer to 315 grains and makes good bare ball loads. Your lead is an alloy and should still shoot okay.
good note hanshi : .606" WW ball weighing 315gr.
my chart shows pure lead .626" weighs 368.4gr.
my chart shows pure lead .615" weighs 350.0gr.
my chart shows pure lead .606" weighs 333.3gr.
my chart shows pure lead .596" weighs 318.2gr.
I should also note, that round balls of the same diameter, but from different moulds,
will weigh slightly differently when cast of the same alloy. This is due to truthiness of spherical shape as well as the sprue's shape itself.