johnny2
It is possible with some bullets - especially Power Belts but not very likely.
You should choose a bullet that fits your bore snugly - except in the case of Power Belts they depend on the skirt holding them in place and most often they do not do this but it is possible.
If you use a sabot/bullet combination there are differenct sizes of sabots available to make sure that this does not happen.
Concials often hold to the bore very tightly.
I can not imagine a patched round ball that is put in correctly could come off the powder.
Hope this helps...