As a rock tumbler it will be most satisfactory using it's rated weight of lead then add 100 - 200g to mill. A drum half full of lead media risks being way over 3lbs
Note that the mill in the link is for 120v if you are getting Cooperman's media you are likely in a 230/240v
Thank you very much for letting me know about the 120v/230v problem. I did know about it, but I am certainly very happy that you said it . Luckily, I have a transformator that should be able to transform the power .
I will try with 100g of 17mm lead balls and see how that works out. Thanks everyone