I believe you said you were working with hollow-ware.
The problem you’re encountering is the size relationship of the torch to the
work. You need a torch that can put out a lot of BTUs per min. Any size torch
will put out the same temperature (dependent on fuel type) flame, however the
amount of heat (BTUs) is dependent on the size of the flame. A larger work piece
requires a larger amount of heat.
If you’re working with silver you can probably get the quantity of heat you need
from a ‘Turbo Torch’, it’s a propane fueled torch usually used by plumbers. I’ve
seen them used to solder 4 in diam copper pipe with 1/8" wall.
Decsribe your problem to a welding supply store, they can help you with torch
selection. If you’re at a University ask some one in the Mechanical Engineering
dept, they may be able to suggest something.