I used clays internationl powder with Lee 1 oz slug, plas wads you have to find
one with thin walls and no ribs in, so when you push the slug in, it does not
buldge the case. My normal load was 19grs of powder.
Used cases work well, some better than others.
Hand loading worked better for me, than machine.
you could also try brass cases from Midway UK.
Its been a couple of years since i last loaded slug.
Hope this helps.
Everyone has their own preferences