This is an old gun with relatively thin chamber walls. I would not advocate using modern CIP ammunition in it. It was not designed for it an may or may not withstand it. Not the kind of game I would like to play.
In any case get it serviced by a good gunsmith before you use it with anything.
I just saw the evidence of a .577 double rifle which blew the chamber out completely last week - probably due to accumulated stresses from incorrect modern solid bullets being used over the years. Caution is advised.
