I would be extremely wary, have the gun expertly checked over by a competent gunsmith, listen and learn.
It should be safe to use commercially loaded cartridges of the correct length for the chambers, but be exceptionally wary of a recommended 'hot' homeload. Certainly never deviate from the recommended homeload recipe by being 'smart' and tinkering to 'improve' the load. With vintage guns of an uncertain pedigree or condition it is so easy to be another statistic in the A&E record books.