[artwhim]

Just a few thoughts:
-Are your walls even, or are areas too thin?
-Are you giving the piece a little insurance heat before it goes into the kiln?
-If using tongs to put the piece into the kiln, are you heating the tongs first so they don't shock the glass?
-Is your annealing schedule long enough?
-Is your piece going directly into a kiln?
-Is your blowpipe steel or glass? A steel one acts as a heat sink, so you have to make sure you keep enough heat in it. A glass one requires a lot of monkeying around to get the piece off and cleaned up so the piece will have lost a lot of heat before going into the kiln, again carefully add more heat.
-Some torches work this kind of piece better because they have more radiant heat. If your torch has an outer fire, I'd make that a nice oxy rich bushy flame.
-Boro lends itself to thin walled large hollow beads better than 104 because it is more forgiving heatwise and the finished piece has greater strength. Although, as long as you don't let your walls get too thin in 104, they are doable.
-Are you decorating with 96 frit? With thin walls, it could be incompatibility issues.