I do top and bottom together, others may approach it differently. The Bill Nittler video/book goes over his process. Mine is similar. He uses a modified torch to heat from the inside. I made some soldering coppers lathe turned and fit to a handle. I heat the coppers with an Oxy acetylene torch. Works well. I will say re-laying ribs is not my favorite job.

http://www.bertramandco.com/
Booking African hunts, firearms import services

Here for the meltdowns