Of course it's best to contact manufacturer.
My real beef suggesting that these single shots can't handle full power smokeless loads is ridiculous. Today an modern single shot reproduction like a falling block should be able to handle anything you put into it. It SHOULD be able to seeing that this stuff mostly starts around 3k and goes up from there.
Really any falling block made recently should be able to outperform any nitro double rifle like 450 nitro express or 470. The single shot is an strong mechanism and metallurgical materials have advanced considerably since 1900 or 1930 for that matter. Just saying a Ruger no1 or an modern Sharp's or HI Wall should be able to run anything.
True the modern falling blocks are strong. It's not the action that is the problem, it's the barrel.
A Pedersoli 74 .45-70 had a problem at the Quigley shoot that had a load of 5744 that let loose and did bad damage to the shooters hand. I might have the photo's from that incident and one let loose down in AZ a friend send me those pictures.
When these rifles are loaded improperly they can detonate like a grenade.
One year I was shooting the match at the Quigley when a Ballard .40-65 blew just to the right of me about 20-30 feet that did bad damage to the person shooting it and parts were scattered around the firing line from that one.
Yes it was a weaker vintage rifle but if loaded wrong they will blow.
