I have a Blackhawk in 45 LC and only shoot lead reloads. When I purchased it 20+ years ago I had the same problem.
I went from standard size .452 to 454 and the thing became an accurate gun at 25 yards.
When you shot the lead, were you getting any lead out the side of the forcing cone or lots of lead residue on the side of the cone?
One suggestion is to have someone else fire the gun just to take you out of the picture. I know that some guns don’t fit me well and it affects accuracy.
I would contact Ruger.
"The difference between stupidity and genius is that genius has its limits" Albert Einstine