nhfrank,
The only way I would shoot 45-90 would be with Pyrodex or black powder.
Hot smokeless loads will be like a miniature .458 Magnum,
check out the loading manuals like Speer and Hornady. They will show tremendously powerful 45-70 loads for your rifle or the Ruger single shot.
Have fun!
whelennut

I like to do my hunting BEFORE I pull the trigger!
There is only one kind of dead, but there are many different kinds of wounded.