A way to keep shot from getting inside hollow beads is this. Find
some plastic mesh. The kind that makes bags for vegetables works well
or the mesh that comes from the fabric store. Cut a long skinny piece
and stuff it into the bead or hollow form. Leave a bit hanging out,
like a little tail. This not only keeps your tumbling media from
getting jammed inside, it also adds some weight to the hollow form,
thus increasing the effectiveness of the tumbling. Cotton wadding
wouldn’t work as well because it would get wet and be hard to remove.
Another trick is to string each bead with the biggest electrical tie
that will go through the hole. When done, cut the tie and pull it
out. That keeps the shot from being jammed inside.
When your tumbling is done, gently pull the tail and all the
stuffing is removed easily.
If you are using an abrasive media, you do need to put the bead in a
sonic between steps to avoid contaminating the subsequent process. Or
you can remove the stuffing, rinse everything well and re-stuff for
the next step.
To remove the steel shot from inside the beads now, try putting them
in your sonic, that usually works. Lacking a sonic, put them in a big
heavy plastic bag and sit and shake them for a while. Eventually one
piece will find its way out and all the others follow quickly.