To get the cavitys cleaned up cast a few bullets & keep em relative to the cavity from which they came. Next drill an appropriate sized hole for a tap , put the tap in a drill, cover bullet with a comet cleanser/h20 paste & spin em slowly in the cavitys.
It won`t take much so go slow, too much will round sharp corners
The mould will not need smokin after the Leementing process.
Only attempt this if you are mechanically inclined. If you are heavy handed, this may not end well. Indication that you are not "mechanically inclined"; if you cannot find the cause of problem by careful inspection.