Shot stuck in beads

I'm considering stuffing the beads with cotton wadding to prevent
this from occurring again. Will this be sufficient? Is there
anything I can do? 

I was casting 2" long curved tubes for someone and I used plastic
tapered things that when you drill a hole in a wall, you insert that
plastic piece and use a screw that expands the plastic to hold
something to the wall. You can get them in different sizes, don’t
know if they come small enough for your beads.

Richard Hart G.G.
Denver, Co.