577 Snider ( large bore... pretty big case capacity ) smokeless loads ???

[Magnum Wheel Man]

so I'll likely start with black powder ( this will be my 1st actual black powder loaded cartridge ) though I could do 50-70 in black powder as well...

but what do you think are the best smokeless powders to use in a larger bore larger case capacity case ??? like 50-70 or this 577 Snider ????

 

[olyinaz]

What firearm? Is it rated for smokeless in the first place? I think a bit more information might be helpful but that's just me talkin'...

Cheers,
Oly