Thanks for the replies. I decided to load them with 16.4 grs. of 2400, which I think I saw on handloads.com. It seems this is not full potential in a Ruger, but better safe than sorry, especially in somebody else's revolver.

I also found a small quantity of 300 gr. plated bullets which in my younger and more foolish days I had loaded into a friend's .445 Supermag at velocities significantly higher than the recommended 1000 FPS maximum. That might be a good candidate for the Mountain Gun at lower velocities.

Dave Sinko