Here's the load I use for my Old Army.
Buffalo Bullet 190 and Triple 7
They're incredibly accurate and strong.
In fact right in the manual Ruger states that you can't overload it.... Hard to believe they'd say that....
I had a first production run Old Army but collectors finally pried it from my hands...
Now I have one of the new stainless models.
I suggest you never shoot anything but Triple Seven in it and you can clean it in 5 minutes with WD-40 rather than an hour with soap and water.
As far as I can tell Triple Seven won't harm a firearm any more than modern smokeless powders and the folks at Hodgdon seem to agree.
*** EDIT *** I just realized that someone might think that I mean you can load an Old Army with modern smokeless powders... YOU CAN'T!!! I'm talking about corrosion and rust!
$bob$