RHD:
Would you really want to bet your fingers on a set of barrels that have been in a fire of unknown duration and temperature? If the ribs are loose they certainly got hot enough to unsolder them.
Heavily rusted also means there are likely pits thus thinning the barrels that have already most likely been weakened by heat. I'm certainly no metalurgist but IMO: The prudent thing to do here is to pass.
Jim

The 2nd Amendment IS an unalienable right.